Hepatitis Ebook

Alternative Hepatitis C Treatments

The therapeutic goals of Natural treatment for Hepatitis C are as follows: Decrease iral load Normalize liver enzyme levels. Enhance/regulate immune system function. Strengthen and promote healthy liver function. Protect the liver, prevent further damage. Virological response; i.e. viral clearance, viral reduction or elimination of the virus. Starve the virus by limiting levels of iron. Optimizing cellular levels of glutathione in the body, making detoxification of the liver possible and enhancing the immune system. Stimulate regeneration of the damaged liver cells. Use of antioxidants to combat the effects of free-radicals generated by the virus. Reduce inflammation. Slow viral replication. Replace all of the inflammation-damaged liver cells. Regulate immune function/prevent auto-immune problems. Cancer preventative measures. Reverse fibrosis to prevent and improve cirrhosis

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Structure and Replication of Hepatitis Delta Virus RNA

Abstract While this volume covers many different aspects of hepatitis delta virus (HDV) replication, the focus in this chapter is on studies of the structure and replication of the HDV RNA genome. An evaluation of such studies is not only an integral part of our understanding of HDV infections but it also sheds new light on some

Hepatitis Delta Virus Background

HDV was discovered following the detection of a novel antigen-antibody system in hepatitis B virus (HBV) carriers (Rizetto et al. 1977). Currently, HDV is classified as a subviral satellite of HBV due to an obligate relationship with HBV infections in nature. However, unlike other satellite viruses, the dependence of HDV on HBV is limited solely to the provision of an envelope of hepatitis B surface antigen for virus assembly. Nevertheless, this dependence requires that natural HDV infections occur as either a co-infection with HBV or as a super-infection of HBV carriers, with the resultant disease usually being more severe than that with HBV alone. Following HDV infection, the

NK Receptor Expression in Chronic Hepatitis C Patients

There is no established view of NK activity in patients with HCV some researchers have reported decreased NK activity in HCV patients, while others have reported levels equivalent to those of healthy individuals (Ahmad & Alvarez, 2004 Golden-Mason & Rosen, 2006). In order to evaluate the function of NK cells in patients with HCV, we separated CD56-positive cells from the peripheral blood of patients with HCV and healthy donors and examined their cytotoxic activity. To K562 cells, a classic NK-sensitive target, CD56-positive cells in patients with HCV showed the same level of cytotoxic activity as those in healthy donors, but to hepatoma cell lines, the cytotoxic activity of CD56-positive cells decreased in patients with HCV. This suggests that the NK-cell receptor expression profile might differ between patients with HCV and healthy individuals. We next comprehensively analyzed NK receptor expression in CD56-positive cells using FACS. The results showed that for KIR, among the...

RNA Editing in Hepatitis Delta Virus

Abstract Hepatitis delta virus (HDV) relies heavily on host functions and on structural features of the viral RNA. A good example of this reliance is found in the process known as HDV RNA editing, which requires particular structural features in the HDV antigenome, and a host RNA editing enzyme, ADAR1. During replication, the adenosine at the amber W site in the HDV antigenome is edited to inosine. As a result, the amber stop codon in the hepatitis delta antigen (HDAg) open reading frame is changed to a tryptophan codon and the reading frame is extended by 19 or 20 codons. Because these extra amino acids alter the functional properties of HDAg, this change serves a critical purpose in the HDV replication cycle. Analysis of the RNA secondary

Mechanisms of Interferon Action and Resistance in Chronic Hepatitis C Virus Infection Lessons Learned from Cell Culture

Abstract Alpha interferon, usually in combination with ribavirin, is currently the standard care for patients infected with hepatitis C virus. Unfortunately, a significant number of patients fail to eradicate their infection with this regimen. The molecular details concerning the failure of many patients to achieve sustained clearance of the virus infection after interferon therapy are currently unknown. The primary focus of this chapter is to provide an overview of interferon action and resistance against hepatitis C virus (HCV) based on our understanding developed from in vitro experiments. Interferon first binds to receptors on the cell surface this initiates a cascade of signal transduction pathways leading to the activation of antiviral genes. Using a cell culture model, we determined that the activation of an interferon promoter (interferon inducible genes) is important for a successful antiviral response against HCV. The level of activation of the IFN promoter by exogenous...

Post Transfusion Hepatitis

Labeling of blood from paid donors, a practice started in 1972, and the implementation of third-generation screening tests for hepatitis B surface antigen markedly reduced transfusion-transmitted hepatitis B but were found to eliminate only about 10 of all post-transfusion hepatitis cases by 1995 (6). Risk for non-A, non-B posttransfusion hepatitis was reduced when potential HIV-positive donors were excluded and was decreased again when donors were tested for the surrogate markers alanine aminotransferase (a marker for acute liver inflammation) and antibody to hepatitis B core antigen (evidence of previous hepatitis B infection) (9). Even greater reductions in the risk of transmission of non-A, non-B hepatitis were described after implementation of a test for antibody to the hepatitis C virus (Table 2) (10). Finally, implementation of nucleic acid testing has reduced the current estimated risk of hepatitis C transmission to approx 1 in 1,500,000 units (8).

HIV and HCV Coinfection Epidemiology and Transmission

Coinfection with HIV and HCV occurs frequently, due to the fact that both are transmitted via the same pathways (parenteral, sexual, vertical). 240,000 people (30 of HIV-infected individuals) are estimated to be infected with both viruses in the USA. Several European countries have even higher rates of coinfection. In Spain, at least 50 of the 130,000 HIV-infected patients are also HCV-positive as a result of the high incidence of i.v. drug users. More than 90 of coinfected individuals are positive for HCV RNA, i.e. have chronic hepatitis C. As HCV is ten times more infectious than HIV on blood-to-blood contact, intravenous drug users and recipients of blood products are particularly susceptible to coinfection. For example, on routine testing of blood products from HIV-infected hemophiliacs treated before the discovery of HCV in the early nineties, HCV antibodies and HCV RNA were detected in the serum of over 90 of patients. The probability of transmission from needlestick injuries...

Course of hepatitis B with concurrent HIV infection

In HIV-infected patients, chronic hepatitis B has an unfavorable course compared with monoinfected patients, and the risk of liver-associated mortality is significantly increased. Data from the Multicenter AIDS Cohort Study (MACS) have demonstrated the unfavorable influence of HIV infection on hepatitis B (Thio 2002). In approximately 5,000 patients observed over a period of 14 years, the risk of liver-associated mortality was 8 times higher than in HBs antigen negative HIV patients (14.2 1,000 person-years vs. 1.7 1,000) and 15 times higher than in HBs antigen negative patients without HIV infection (14.2 1,000 vs. 0.8 1,000). Liver-associated mortality due to hepatitis B has increased significantly since the introduction of HAART in this cohort. In addition to increasing mortality, HIV coinfection accelerates the progression of hepatitis B and increases the risk of cirrhosis. Histological analysis of a series of 132 homosexual men with chronic hepatitis B, of which 65 were...

The Essential Role of the Adaptive Immune Response in HCV Clearance

In the absence of high levels of immunosuppression, HCV is a non-cytopathic virus. In the absence of an ongoing immune response, it infects and persists in target cells, predominantly hepatocytes, without inducing inflammation and damage. This has been demonstrated in both experimental chimpanzee models (Thimme et al., 2002) and in drug users or humans who were accidentally infected with contaminated needles during health care practice (Thimme et al., 2001 Timm et al., 2004). In these studies, increases in viremia were not associated with parallel increases in serum transaminase levels, thus reflecting an absence of hepatocyte damage. Furthermore, following liver transplantation, infection does not lead to liver damage for a 3-week period despite high levels of virus. The only cytopathic lesion that has been directly ascribed to HCV is the association of Genotype 3 infection with steatosis, the accumulation of lipids in hepatocytes (Pawlotsky, 2004). Although non-cytopathic, gene...

Role of the Innate Immune System During HCV Infection

Of events leading to innate intracellular immunity. In the case of HCV, the double-stranded RNA initiates two major pathways of host defense by binding to Toll-like receptor 3 and retinoic-acid inducible gene I (RIG-1) reviewed in (Gale & Foy, 2005) . Several reports in both chimpanzee and humans indicate that the virus activates the innate immune response before and during acute infection by inducing secretion of endogenous type I interferon (IFN-a and - ) and by activating NK cells. Analysis of gene microarray experiments from experimentally infected chimpanzee liver biopsies has revealed the induction of a broad range of IFN-a inducible genes (ISGs) (Bigger et al., 2001, 2004 Su et al., 2002), including some involved in the regulation of NK cells, confirming the induction of IFNs during the course of acute infection. Expression of IFN has three major roles (1) to induce ISGs that have an antiviral action (2) to induce the maturation of immune effector cells and (3) to create a...

The Role of the Adaptive Immune Response During HCV Infection

Seroconversion in HCV occurs approximately 7 to 31 weeks after primary infection (Pawlotsky, 1999, 2004), and some HCV-specific antibodies are effective in blocking in vitro infection of target cells by HCV (Farci et al., 1994). However, in both chimpanzees and humans, naturally acquired anti-HCV antibodies generated during this infection do not seem to be protective upon secondary infection with HCV, indicating that these molecules play a limited role in preventing the spread of the virus (Farci et al., 1992 Lai et al., 1994). Moreover, studies in chimpanzees indicate that resolution of infection can occur without the development of detectable antibody responses (Cooper et al., 1999). In addition, recent studies using HCV pseudotyped particles indicate that neutralizing anti-HCV antibodies occur far more commonly in persistently infected individuals than in those who clear the virus (Bartosch et al., 2003 Logvinoff et al., 2004 Meunier et al., 2005). A recent report has suggested...

Pathogenesis of HHV6associated hepatitis

As described above, HHV-6 can directly cause hepatitis, but its mechanism of liver injury is unknown. HHV-6 may directly damage hepatocytes, or the immune and inflammatory response to the virus may cause liver damage. HHV-6 DNA, RNA, and antigens were detected in the hepatocytes of affected livers by in situ hybridization analysis (Mason et al., 1996 Ozaki et al., 2001 Ishikawa et al., 2002). These observations strongly suggest HHV-6 has the potential to directly damage he-patocytes during active infection. HepG2 cells, a well-differentiated liver cell line, are permissive for HHV-6 infection (Cermelli et al., 1996 Inagi et al., 1996). Infected HepG2 cells produce HHV-6 antigens and infectious viral progeny. Moreover, HHV-6 infection leads to the release of transaminase, a marker of liver cell damage (Cermelli et al., 1996). Inflammatory cytokines likely play an important role in the observed liver dysfunction, and the development of viral hepatitis is closely associated with the...

Functional and Clinical Significance of Hepatitis D Virus Genotype II Infection

Abstract Hepatitis D virus (HDV) infection is one of the important etiologies of fulminant hepatitis and may aggravate the clinical course of chronic HBV infection to cirrhosis and liver failure. HDV was classified into three genotypes. Recent molecular phylogenetic analysis of HDV suggests atleast seven major clades. The genotype I HDV is widely spread, genotype II is found in East Asia and genotype III HDV is prevalent in South America. The genomic size is 1682-1685 nucleotides (nt) for genotype II, and 1676 nt for genotype IV (IIb). The divergence in HDV nucleic acid sequences between genotype II and other genotypes varies from 13.8 to 35.3 . The divergences in the HDAg-coding region may range from 17.8 to 29.8 between genotype II and other genotypes. There is no genotypic or size restriction on the interactions of either the small or the large hepatitis delta antigens (HDAgs) between genotypes I and II, and there is also no genotypic incompatibility during co-package of HDAgs of...

CD4 T Cells During Acute and Chronic HCV Infection CD4 T Cells in Acute Infection

Most studies investigating CD4+ T cell responses in HCV have been performed using human peripheral blood mononuclear cells (PBMC). Early studies have suggested that most patients in whom the virus persists develop a defective blood CD4+ T cell response to the recombinant HCV proteins' core, nonstructural protein 3 (NS3), NS4, and NS5 during the acute phase of the disease (Diepolder et al., 1995) (Figure 2). In contrast, individuals who resolve infection exhibit robust HCV-specific CD4+ T cell proliferation (Figure 3). Although there are some exceptions (Thomson et al., 2003), these results have been confirmed in subsequent studies Fig. 2 Schematic representation of the evolution of HCV infection and of the cellular immune response in individuals developing persistent infection. Dashed lines and question marks represent hypothetical pathways of activation or regulation Fig. 2 Schematic representation of the evolution of HCV infection and of the cellular immune response in individuals...

Memory T Cells in HCV Infections

Humans and chimpanzees resolving HCV infection develop acute hepatitis characterized by expansion of both CD4+ and CD8+ T cells and control of viremia. In these individuals, T cell numbers increase and then decrease as in other cellular immune responses. These individuals sometimes develop a resurgence of HCV replication that might reflect transient viral escape before the establishment of a stable memory CD4+ and CD8+ T cell pool (Bowen & Walker, 2005a) (Figure 3). Once established, T cell memory lasts for many years (Lechner et al., 2000 Takaki et al., 2000 Chang et al., 2001 Day et al., 2002, 2003b Rosen et al., 2002 Wertheimer et al., 2003) even when antibodies to HCV can no longer be detected in serum. As it is the case for several viral infections, it is not clear whether memory T cells persist in the total absence of HCV or whether there is a reservoir of HCV that maintains the memory response. Memory T cells identified in the blood using MHC tetramers are present at...

Some Fundamental Aspects of HCV Infections

One of the most striking characteristics of the adaptive immune response to HCV is the inability of this response to mediate viral clearance in the majority of infected individuals, thus enabling viral persistence and ensuing chronic necroinflammatory liver disease. The outstanding question that arises from our current knowledge of the adaptive immune response to HCV could be summarized as follows Why does infection persist in the majority of individuals despite a detectable immune response in many, while some individuals control viremia and resolve infection Obviously, this is a very complex issue, with multiple mechanisms potentially involved in inhibition of the induction and maintenance of an effective anti-HCV immune response. However, any model of defective anti-HCV immunity needs to take into account the following observations 1. There is no general immunosuppression associated with HCV infections. Critically, the inability to mount an effective immune response against HCV is...

Role of MHC Haplotype in HCV Persistence

It is unlikely that the outcome of the immune response is entirely genetically determined. For CD4+ T cells, it is possible that the MHC class II haplotype and thus the range and type of epitopes that are targeted during the immune response play some role in HCV persistence. Some MHC class II allotypes, such as HLA-DR 1*0701, have been associated with HCV persistence (Fanning et al., 2001), while other allotypes (DR 1*0101, HLA-DR 1*1101, and DQ 1*0301) are linked to sustained T helper response and or a self-limited disease (Alric et al., 1997 Minton et al., 1998 Thursz et al., 1999 Harcourt et al., 2001). Likewise, the CD8+ T cell response during acute hepatitis does not seem to be preferentially biased toward any particular HCV protein or epitope. Some MHC class I allotypes, such as HLA-Cw*04, have been associated with HCV persistence (Thio et al., 2002) and HLA-B27 with protection (Neumann-Haefelin et al., 2006). However, some studies (Cooper et al., 1999 Lauer et al., 2002...

Early Events Influencing the Outcome of HCV Infection

Several studies have characterized anti-HCV immune responses during the acute phase of infection when both CD4+ and CD8+ T cells are detectable, in an attempt to determine whether there are differences that distinguish self-limiting versus persisting infections. Although these studies have provided important information on the breadth and repertoire of these responses, it is tempting to speculate that differences

Hepatitis C Virus and Hepatocellular Carcinoma

As early as the days of Hippocrates, hepatitis has been described as a disease that occurs in the young and shows the cardinal symptom of jaundice, which sometimes develops into a critical condition. Ironically, research on hepatitis progressed rapidly during World War II because injuries and the terrible sanitary conditions of the battlefields caused serious hepatitis epidemics. People recognized that hepatitis could be classified into two types infectious and serumal. The former became known as hepatitis A and the latter as hepatitis B. After the war, the hunt for hepatitis viruses had begun. First, the hepatitis B virus (HBV) was identified in 1967 by Blumberg, who was awarded a Nobel Prize in recognition of his discovery. Next, the hepatitis A virus (HAV) was discovered in 1973. These discoveries were thought to have clarified the causes of hepatitis, but by the following year, it was acknowledged that many cases of hepatitis were not caused by either HAV or HBV (Prince et al.,...

Hepatitis Delta Virus

The cover illustration is a simplified structure of hepatitis delta virus showing the internal ribo-nucleoprotein complex, which contains the circular RNA genome and the two forms of the hepatitis delta antigen the envelope proteins ofhepatitis B virus form the exterior of the virus. The inset is an electron micrograph of purified hepatitis delta virus particles, and was kindly provided by Dr. John Gerin. The background immunofluorescence image is oftransfected cells expressing hepatitis delta antigen, and was kindly provided by Dawn Defenbaugh.

Functional Analysis by HCVpp Assay

Because they incorporate envelope glycoproteins from heterologous viruses and integrate and express reporter genes from defective genomes, retrovirus vectors have been very useful in investigating the mechanisms by which various viruses attach and enter their target cells (21-23). The retrovirus-based HCVpp assay described in this chapter, developed by Bartosch et al. (10), Fig. 6. Immunoprecipitation of the E1E2 hetrodimer. Radiolabeled proteins from the cell extracts (CE, panels A and C) and medium (HCVpp, B and D) of HEK 293-T cells co-transfected with the MLVgag-pol + MLV-GFP (lane 2) + a plasmid expressing E1E2 derived from HCV genotype 1a (lane 1) were immunoprecipitated using an anti-E2 MAb AP33 and the immune complexes analyzed under reducing and non-reducing conditions as shown. Aggr, aggregate. Fig. 6. Immunoprecipitation of the E1E2 hetrodimer. Radiolabeled proteins from the cell extracts (CE, panels A and C) and medium (HCVpp, B and D) of HEK 293-T cells co-transfected...

Hepatitis B

Age-related processes play a very important role in the population dynamics of hepatitis B virus (HBV) (Medley et al., 2001). This infection has similarly been estimated to result in 1 million deaths each year, but mainly in adulthood as a result of liver cancer and cirrhosis as with measles, however, there is a safe and effective vaccine. In contrast to measles, infection with HBV can result in persistent infection over a period of decades, and additionally the probability of persistent infection is much greater if infection occurs in early childhood. The modes of transmission of HBV are similar to those of HIV (though HBV is very much more infectious), such as through sexual contacts, health interventions, intravenous drug use (IVU) or at birth from mother to child (Edmunds et al., 1996 Williams et al., 1996). These processes all have a strongly age-related or age-determined component. Also, in general, the endpoint of many persistent HBV infections, such as liver cancer or...

Hepatitis A B E

Hepatitis A is a common problem in rural areas of developing countries. There is a declining level of antibodies to hepatitis A in developed countries and adults are at special risk so 1 or 2 doses of hepatitis A vaccine should be given. If there is insufficient time a single injection of human immunoglobulin (IG) can give protection for 3 to 6 months. It is safe for all age groups but children under 8 years should not need it. A blood test for hepatitis A antibodies should be carried out to determine a person's immunity. Hepatitis B is endemic in South-East Asia, South America and other developing countries. Vaccination is recommended especially for people working in such countries, particularly those in the health care area or those who may expect to have sexual or drug contact. If patients have a 'negative' HBV core IgG titre, then vaccination would be worthwhile (3 doses 0, 1 and 6 months). Hepatitis E has a high mortality rate in pregnant women.

HHV6 and hepatitis

Mild elevation in hepatic transaminase levels during infection. Indeed, approximately 4 (four cases) of 89 infants with primary HHV-6 infection had signs of hepatic injury during viral infection (Asano et al., 1991a). In these cases, patients had a transient elevation in serum hepatic transaminase levels that completely resolved without any specific treatments. However, one case report described chronic hepatitis caused by HHV-6 infection in one 20 month old, otherwise healthy boy (Tajiri et al., 1997). Chronic hepatitis was confirmed by pathological analysis, and viral DNA was detected in liver tissue by polymerase chain reaction (PCR) and in situ hybridization. In these samples, HHV-6 DNA is localized to the nuclei of hepatocytes, the sinusoidal cells, and the nuclei of the epithelial cells of the intra-hepatic bile ducts. Chronic hepatitis in young children can be caused by a variety of viruses, such as hepatitis B virus, hepatitis C virus, and CMV. In addition to these viruses,...

Sensitivity to Ribavirin

Some years ago it was shown that ribavirin could block the replication of HDV in primary woodchuck hepatocytes (Choi et al. 1989 Rasshofer et al. 1991). Recent studies confirm that this occurs in cell lines undergoing HDV replication (Chang et al. 2006). Moreover, this inhibition can be achieved with 30 M ribavirin, a dose low enough to avoid cell toxicity. In contrast to this, others have cited that ribavirin treatments for HDV-infected patients are not effective (Hoofnagle 1998). However, given that ribavirin treatment is demonstrably selective for HDV replication in cultured cells, further studies in patients maybe warranted. What might seem a possible hindrance to patient studies is that a side effect of ribavirin treatment can be anemia (Galban-Garcia et al. 2000). However, such side effects can be controlled, as judged by the current acceptance of ribavirin (combined with pegylated interferon) as part of a treatment for chronic hepatitis C virus infection. Also, ribavirin might...

Structure of HDV and Hdv Rna

HDV is a small RNA virus consisting of spherical particles of about 36 nm in diameter. The virion itself is comprised of a short (1.7 kb) single-stranded, circular RNA that exists as a ribonucleoprotein complex with the only HDV-encoded protein, hepatitis delta antigen (HDAg). Together these form a roughly spherical core structure that is enveloped by hepatitis B surface antigen (HBsAg). There are approximately 70-200 HDAg molecules per RNA molecule (Ryu et al. 1993 Gudima et al. 2002). Fig. 1 Genome organization of HDV RNA. Numbering is based on that of Wang et al. (1986). G, genomic HDV RNA AG, antigenomic HDV RNA S-HDAg, small hepatitis delta antigen L-HDAg, large hepatitis delta antigen

Control of DC Function by NK Cells

Next, we examined DC maturation and functional activation resulting from co-culture with hepatoma cells and NK cells using NK cells from patients with HCV instead of those from healthy donors. The stimulation of IM-DCs using the supernatant of a 24-hour co-culture of NK cells from HCV patients with hepatoma cells resulted in suppressed DC maturation and allostimulatory capacity compared with the case in which we used NK cells from healthy donors. In order to examine whether NKG2A signals from HLA-E during a mixed culture of hepatoma cells and NK cells are involved in this inhibition of DC maturation and activation, we conducted an inhibition experiment by adding anti-NKG2A antibody during the mixed culture. DC maturation and activation resulting from culture supernatant stimulation were enhanced by adding anti-NKG2A antibody either in the case of NK cells from healthy donors or in the case of those from patients with HCV. However, DC maturation and activation were more notably...

HDV Produces Two Forms of HDAg from the Same Gene

Hepatitis delta virus (HDV) is often compared to viroids because of the characteristic unbranched rod secondary structure formed by its RNA and the relatively small size of its genome. However, unlike viroids, HDV does contain one gene that encodes the sole viral protein, HDAg. Early analyses showed two electrophoretic forms of HDAg in liver and viral particles isolated from serum (Bergmann andGerin 1986 Bonino et al. 1981,1984,1986). (These forms were sometimes referred to by their apparent molecular weights, p-24 and p-27 they are denoted here as S-HDAg and L-HDAg for short and long, respectively.) Following the cloning of HDV cDNAs (Makino et al. 1987 Wang et al. 1986), a series of studies illuminated the functional roles of S-HDAg and L-HDAg in HDV replication S-HDAg is required for replication of HDV RNA, and L-HDAg is required for the formation of HDV particles (Chang et al. 1991 Glenn et al. 1992 Hwang et al. 1992). Early studies found that L-HDAg also inhibits HDV RNA...

Isoprenylation of LHDAg

HDV isolates are classified into three genotypes I, II and III based on the differences in their nucleotide sequences. The CXXQ motif in genotype III is CTQQ and is less efficiently farnesylated than other genotypes (O'Malley and Lazinski 2005). During the early phase of HDV replication, the small form of hepatitis delta antigen (S-HDAg) is more abundant than L-HDAg, and the L-HDAg S-HDAg ratio increases when replication progresses. The level

Role of LHDAg Farnesylation in the HDV Replication Cycle

In the HDV packaging process, hepatitis B surface antigen (HBsAg) interacts with L-HDAg to form particles this process can occur even in the absence of HDV RNA (Hwang and Lai 1993). HBsAg is mainly localized in the endoplasmic reticulum (ER) membrane, while the localization of newly synthesized L-HDAg is very dynamic (Hourioux et al. 1998). Analyses of transiently transfected cells revealed the sequential appearance of L-HDAg in the nucleoplasm, then in the nucleolus, and finally in nuclear speckles (Shih and Lo 2001). Prenylated L-HDAg is concentrated in the nuclear speckles. Far-Western protein blotting analysis indicated a direct protein-protein interaction between HBsAg and L-HDAg (Hwang and Lai 1993). The L-HDAg isoprenylation also mediates this protein-protein interaction. When HDV particles assemble, L-HDAg must interact with HBsAg in the ER membrane. From where the prenylated ER-associated L-HDAg comes remains unknown. The protein is probably either transported from the...

Mechanisms of Interferon Resistance

The nucleotide sequences of HCV genomes isolated from patients from different parts of the world are quite heterogeneous. Six major genotypes of HCV virus show 30-50 variation in their nucleotide sequences (Simmonds, 2004). More than 50 subtypes of HCV have also been described, showing 15-30 difference in their nucleotide sequences. Isolates of HCV from a single patient can show a 1-5 difference in their nucleotide sequences (Hoofnagle, 2002). The sequence variability suggests that the HCV genome mutates frequently during replication and circulates in the serum as a population of quasispecies. Interferon therapy, usually in combination with ribavirin, is the standard treatment for chronic HCV infection throughout the world. HCV genotype is the most important predictor of treatment outcome. Sustained virologic responses can be achieved in up to 82 of patients infected with genotypes 2 and 3, whereas a substantially lower response rate, around 4050 , is achieved in patients with...

The Effect of HDV Infection on the HBV Life Cycle

Since HDV is directly dependent on HBV for propagation, it can be transmitted concomitantly with HBV to an individual who has no history of prior HBV infection, this is referred to as a coinfection pattern - or it can be transmitted to an HBV chronic carrier, this is referred to as superinfection. Coinfections are often acute and self-limiting, and they result in a concomitant replication of both HBV and HDV, whereas superinfections cause severe acute and chronic type D hepatitis in 70 of cases. They also lead to the inhibition of HBV replication during the acute phase of HDV infection. This phenomenon has been describedinbothhumansand experimentallyinfectedchimpanzees, but it remains poorly understood (Chen et al. 1988 Sureau et al. 1989 Wu et al. 1991). It could result from a direct suppression of HBV replication exerted by the coexpressed HDV proteins, RNA or RNPs, or could be the consequence of an indirect interfering mechanism driven by inflammatory cytokines. The suppressive...

Attractive Features of Prenylation Inhibition Based Antiviral Therapy

It is worth emphasizing that prenylation inhibition-based antiviral therapy has implications for other viruses besides HDV which are found to have similarly prenylated proteins. Indeed a CXXX box motif is present in proteins of numerous other medically important viruses, as well as in agents with a potential for bioterrorism (Elazar and Glenn 2005). The precise role played by prenylation, however, may differ in each case and need not be restricted to mediating assembly as in HDV. For example, the polymerase proteins of hepatitis A virus and foot and mouth disease virus have a conserved CXXX box. Because the replication of these positive single-strand RNA viruses is thought to occur in intimate association with intracellular membranes, prenylation of these proteins may provide a membrane anchoring function for the catalytic subunit of the respective replication complexes. On the other hand, the UL32 gene product of herpes simplex virus (HSV), which is thought to be involved in virus...

Viral Genetics of HBVand HDV

Despite an effective vaccine, infection with hepatitis B virus (HBV) is mainly transmitted through the mother-to-neonate route in endemic countries. In most cases, chronic infection results and the transmission will therefore occur from generation to generation. HBV could be considered as an indirect marker of population migration. Transmitted from the mother, it might be considered as an alternate to mitochondrial DNA (mtDNA) (Ingman et al. 2000). MtDNA analyses indicate that around 59,000-100,000 years before present, earth colonization might have occurred from Africa to the Middle East, Asia then to Australia, Europe and to Americas. Several hypothesis have been proposed to link the HBV to human evolution and dispersal around the globe (reviewed in Simmonds 2001). (1) The existence of Hepadnaviridae in other primates, mammals and birds makes possible a co-speciation of HBVs during evolution. (2) The higher divergence of the South American HBV genotype F strains (HBV F) could have...

HDV Genetic Distances and Geography

Similar to HCV (Morice et al. 2001) and HBV (Ganne-Carrie et al., 2006), the delta viruses characterized in Paris (France) showed a wide African distribution. For example, the six full-length viral RNA sequences were obtained from five patients from Western or Central sub-Saharan African countries (Cameroon, Guinea, Ivory Coast, Mali, and Republic of Congo) and from an adult Polish woman who had lived in Cameroon for 3 years. To determine whether the geographic distribution of the HDV isolates was correlated with their levels of sequence divergence, we compared the Kimura-2-parameter pairwise distances between full-genome sequences with the relative geographic distances matrix of the capitals of the countries where the patients had been infected. To compare two quantitative continuous variables, we decided to calculate the correlation coefficient to evaluate the degree of proportionality of data sets. When the ubiquitous type-I sequences were removed, a significant statistical...

HDV Genetic Variability and Clinical Patterns

The wide radiation of HDV we describe might contribute to the spectrum of pathologies associated with HDV. For example, specific liver lesions, including morula cells, have been observed in severe hepatitis in African and Amazonian patients (Casey et al. 1993 Parana et al. 1995). It is therefore considered that the association of HDV-3-HBV F leads to severe acute hepatitis. By contrast HDV-2 and HDV-4 have been typically associated with less severe hepatitis disease than Type I-associated infections (Wu et al. 1995). However, a recent study among the Miyako island strains suggests that the HDV-4 Okinawa subgroup (labelled IIb-M in the original paper) induces a greater progression to chronic hepatitis and to cirrhosis (Watanabe et al. 2003). Type-I viruses have a wide spectrum of pathologies, ranging from severe fulminant hepatitis in Sweden (Hansson et al. 1982 Zhang and Hansson 1996), Russia (Flodgren et al. 2000) and Taiwan (Wu et al. 1995) to very mild disease in the town of...

Comparison Between Genotypes I and II HDV

It hasbeenreportedthatgenotypeIIHDV infectionisrelativelylessfrequently associated with fulminant hepatitis at the acute stage and less unfavorable outcomes (cirrhosis or HCC) at the chronic stage as compared to genotype I of the same area 18 . This study was composed of symptomatic inpatients and asymptomatic outpatients for regular check up. In a longer follow-up for more than 15 years, about 45 of patients with chronic genotype I HDV infection survived, while more than 75 of patients with chronic genotype II HDV infection remained alive 63 . The difference is statistically significant. The long-term prognosis of patients with chronic genotype II HDV infection seems better than that reported previously in western countries where only genotype I HDV is currently found 10,11,17 . All the patients in the study by Ivaniushina et al. had a history of chronic liver disease, and all except two presented with grave liver disease or cirrhosis 26 . It is not surprising that there was no...

Influence of Replication and Genotypes of HBV

Smedile et al. reported that HBV replication modulates pathogenesis of HDV in chronic hepatitis D 16 . Wu et al. also reported that persistent replication of HBV or HDV are associated with elevated serum transaminase levels 14 . Based on an intergroup divergence of 8 or more in the complete nucleotide sequence, HBV can be classified into eight genotypes A-H 47 . Genotypes andcorepromotermutations ofHBVhavebeenreportedtobeassociatedwith time of HBeAg seroconversion, HBV DNA levels, treatment response to interferon and long-term outcomes 47-62 . Because chronic hepatitis D patients still have underlying chronic hepatitis B, replication status, genotypes and mutations of HBV may also influence clinical course and outcomes of chronic HDV infection. In a recent study in our laboratory, persistent replication of HBV or HDV was associated with higher adverse outcomes (cirrhosis, HCC or mortality) compared to those who cleared both viruses from sera 63 . HBV genotype C is also a significant...

CD4 T Cells in Chronic Infection

Chronic infections are characterized by a permanent, almost complete, loss of HCV-specific CD4+ T cells in the blood (Figure 2). PBMC harvested from patients infected for many years with HCV failed to proliferate and or produce IFN-y or exhibited oligoclonal diversity (Gerlach et al., 1999 Lechner et al., 2000 Schirren et al., 2000 Day et al., 2002 Rosen et al., 2002 Ulsenheimer et al., 2003 Wertheimer et al., 2003). The relative lack of circulating HCV-specific CD4+ T cells has recently been confirmed more directly using MHC class II tetramers (Day et al., 2003b). Although CD4+ T cells are hard to detect in the blood, they are not totally absent, however. Following HCV-specific stimulation, a very low percentage of CD4+ T cells that upregulated expression of the alpha chain of the IL-2R (CD25), an early marker of activation, was detected among PBMC from chronically infected subjects (Ulsenheimer et al., 2003). Furthermore, it has been possible to derive some CD4+ T cell lines...

Natural History of the Clinical Course of HDV Infection

HDV infection in patients shows two courses of disease. HBV and HDV coinfection induces a disease similar to the classical acute HBV hepatitis with a cellular immune response to HBV resulting in a downregulation of HBV replication by cytokines and an elimination of infected cells by cytotoxic cells (Chisari and Ferrari 1995 Guidotti et al. 1996b). Neutralizing antibodies against HBsAg prevent hepatocytes from reinfection with HBV and HDV. The humoral immune response to HDV in this mode of infection is characterized by low titers of anti-HDV, which disappear soon after infection (Rizetto 1981, 1984). A specific immune response against HDV may not be required in the context of HBV clearance because HDV, as a helper-dependent virus, essentially needs HBV envelopes to form complete particles.

CD8 T Cells in Acute Infection

CD8+ T cells have been investigated extensively in HCV infections. This has been facilitated by the availability of MHC class I tetramers. Studies in infected chimpanzees and humans using both functional methods of CTL identification and MHC class I tetramers have demonstrated that increases in serum transaminase levels and clearance of the virus during the acute phase are generally associated with the emergence of a strong CTL response in the blood and the liver 1 to 3 months after infection (Cooper et al., 1999 Thimmeet al., 2001,2002 Shoukry et al., 2003 Cox et al., 2005a) (Figure 2). Up to 8 of the blood CD8+ T cells can be specific for a single HCV epitope at the peak of the acute response (Klenerman et al., 2002). Viral clearance follows the entry and accumulation of HCV-specific IFN-y-producing T cells within the liver (Thimme et al., 2002). Consistent with this observation, a poor CD8+ T cell response is associated with viral persistence (Cooper et al., 1999) (Figure 2). The...

IsHDVaCytopathic Virus

Both small and large HDAg and expressing these proteins in the liver do not develop any form of liver disease. Hence, the hepatitis in humans may be induced rather by the immune response than by HDV itself (Guilhot et al. 1994). The issue of the cytotoxicity of HDV itself has been investigated in different in vitro systems and yielded conflicting results. More recently, Wang et al. studied this issue extensively (Wang et al. 2001). When cells transfected with replication-competent HDV-cDNA were followed, a progressive decline in viral RNA replication and a steady decrease in the cells expressing HDAg were found. However, in transient transfection assays, no evidence was found to link HDV replication to apoptosis or cell cycle arrest. Thus, HDV does not appear to be acutely cytotoxic. In dividing cells, however, HDV replication was associated with a slight growth disadvantage. The authors discuss that this may not cause hepatitis in vivo but might contribute to impaired liver...

TCell Immune Responses

Negro et al. demonstrated that rechallenge with HDV of chimpanzees, which had apparently recovered from a first HDV infection, resulted in the reappearance of HDV replication, sometimes associated with hepatitis (Negro et al. 1989). However, only low levels of viremia were detected and ALT elevations, when present, were mild. This finding suggests that at least a partial immunity against HDV can be raised.

CD8 T Cells in Chronic Infection

Between the acute and chronic phases of HCV, the number of HCV-specific CD8+ T cells declines dramatically. Recent studies (Cox et al., 2005a) in which 23 infected patients were sampled monthly during this transition have revealed that the breadth of the response was set early in infection and that early responses became unde-tectable, while no new responses were formed. Despite early reports based on IFN-y production or CTL activity suggesting that CD8+ T cells were not detected in the blood of chronically infected patients, CD8+ T cell clones specific for HCV can be derived from the liver of humans and chimpanzees in which the virus persists (Koziel et al., 1992, 1993, 1995 Kowalski et al., 1996 Nelson et al., 1997 Wong et al., 1998 Eckels et al., 1999). The presence of anti-HCV-specific CTLs have been confirmed using MHC class I tetramers. This powerful immunological tool has demonstrated that the liver contains a higher frequency of HCV-specific T cells than the blood (He et al.,...

Immunization with HDV Protein

Recently, the same HDAg expressed in yeast was used in another study for vaccination and challenge of eight woodchucks (D'Ugo et al. 2004). Four animals were immunized with HDAg using CFA IFA as adjuvant, the other four with HDAg using MF59 as adjuvant. MF59 is an oil mineral-water emulsion which has been shown to augment the antigen-specific humoral immune response and to induce a Th-cell response that is more type 2-like in nature (Verschoor et al. 1999). The humoral immune response was detected earlier and at higher titers in the woodchucks immunized with HDAg CFA vs. those immunized with HDAg MF59. The Th-cell immune response was already described (see Sect. 3.3.3). After challenge HDV RNA was detected at 2-4 weeks in all animals, indicating that neither of the vaccines was able to protect from superinfection despite the presence of anti-HDV and a Th-cell immune response to HDAg. However, differences were observed in peak serum HDV RNA levels and persistence namely, the HDAg CFA...

WoodchuckHDV Inoculum Derived from a Molecular Clone Analysis of Genetic Changes Occurring During Acute and Chronic

The determinants of the outcome of HDV superinfection are not known. Analyses of the viral genetics of hepatitis C virus have indicated that progression to chronic infection is correlated with sequence changes and increased sequence diversity in the hypervariable region of the envelope protein (Farci et al. 2000). Previous studies of genetic changes that occur during the course of HDV infection have either analyzed sequence modifications that occur over time in HDV RNA isolated from the sera of chronically infected patients (Chao et al. 1994, Imazeki et al. 1990, Lee et al. 1992), or from the liver of an infected woodchuck at the end of several serial passages (Netter et al. 1995). However, none of these studies addressed the role of viral genetic changes in the establishment of chronic infection. One of the more interesting observations of the genetic changes occurring during the course of infection was that in nearly all animals, a limited number of modifications had occurred in the...

Vaccine Strategies for HDV

Responses are not protective against HDV infection (Karayiannis et al. 1990) is not particularly surprising given that HDAg is not exposed on the surface of the virion. However, it appears that some form of immunity follows acute, self-limiting infection because hepatitis B carrier chimpanzees superinfected with HDV were resistant to rechallenge with HDV 6 months later (Purcell et al. 1987). Most likely, the alteration of the course of infection by some vaccines is due to the ability to elicit appropriate cell mediated immune responses. However, there appears to be no correlation between vaccine efficacy and antiHD T-cell proliferative responses (Fiedler et al. 2001). Perhaps, cytotoxic T lymphocyte activity is the more important contributor to clearance of virally infected cells. Future vaccine studies may benefit from measurement of cytotoxic T lymphocyte activity induced by vaccines and or HDV infection.

Therapy for HDV Based on Inhibition of the Helper Hepadnavirus

There is currently no generally accepted effective therapy for type D hepatitis (see Niro et al. 2005 for a review), and liver transplantation is the only option for the associated end-stage liver disease (Wright and Pereira 1995). The dependence of HDV on HBV could suggest that successful treatment of HDV infection would follow successful treatment of the supporting HBV infection. Unfortunately, this does not always appear to be the case. Although treatment of chronic HBV carriers with lamivudine (b-L-2',3'-dideoxy-3'-thiacytidine, 3TC) leads to decreased levels of HBV in serum and improved liver histology (Dienstagetal. 1995 Laietal. 1998 Nevensetal. 1997),in patients with chronic delta hepatitis prolonged lamivudine therapy neither lowers HDV RNA levels nor ameliorates disease activity, even though HBV viremia is reduced (Lau et al. 1999 Wolters et al. 2000). Similarly, treatment with famciclovir was not effective against HDV infection (Yurdaydin et al. 2002). The most likely

Mechanisms of Interferon Action

Our understanding of interferon action against the hepatitis C virus is possible due to the availability of HCV cell culture models. Work on this area began almost 10 years ago by Shimizu (1992, 1993, 1996), where HCV replication models were developed in lymphoid cell lines. Subsequently, full-length chimpanzee infectious clones for HCV were developed by the laboratories of Dr. Charles Rice, Rockefeller University (Kolykhalov et al., 1997), and Dr. Jens Bukh of NIH (Yanagi et al., 1997). An initial attempt to establish HCV replication models in hepatic cells was made using full-length RNA transfection (Yoo et al., 1995 Dash et al., 1997). The levels of HCV replication in these models remained low and required the RT-PCR method to detect HCV replication. These technical difficulties have demanded the development of a more reliable cell culture system for HCV. A significant advance in this area took place after development of a subgenomic replicon-based model by Lohmann and...

The SHBsAg Protein and the Assembly of HDV Particles

It is worthy of note that the members of the Hepadnaviridae family closest to HBV, namely the Woodchuck hepatitis virus (WHV) and the Woolly monkey hepatitis B virus (WMHBV), can assist in HDV propagation because their small envelope proteins (S-WHsAg and S-WMHBsAg, respectively) are competent for HDV RNP envelopment (Barrera et al. 2004 Ponzetto et al. 1984 Ryu et al. 1992). Experimental transmission of HDV has been achieved in woodchucks, and this animal model has been useful to study the interactions between HDV and the helper Hepadnavirus. In contrast, the envelope protein of a more distantly related Hepadnavirus, namely the Duck hepatitis B virus (DHBV), is unable to package the HDV RNP (O'Malley and Lazinski 2005). Therefore, determinants that are specific for HDV maturation on the S-HBsAg

Secretion of Soluble MICA into Serum in HCC and NKG2D Expression in NK Cells

In order to examine the importance of sMICA in liver disease, we conducted ELISA quantitation of serum sMICA from healthy donors and patients with chronic HBV HCV and HCC (Jinushi et al., 2005). Only a small amount of sMICA was detected in a small number of cases of healthy donors and patients with chronic hepatitis, while notably larger amounts of sMICA were detected in some patients with HCC. We also conducted the test according to the HCC stage and observed that the number of sMICA positive cases was notably more frequent for advanced HCC than for early HCC. We conducted FACS analysis of NKG2D expression in CD56-positive cells from healthy donors and patients with HCC (sMICA positive negative) and chronic HCV. The results showed that the level of NKG2D expression in patients with hepatitis or HCC (sMICA negative) was the same as that in healthy donors, while the level of NKG2D expression in patients with HCC (sMICA positive) was decreased. Next, in order to examine whether sMICA is...

HDV Ribozymes

Abstract The self-cleaving RNA sequences, or ribozymes, in the genomic and antige-nomic strands of hepatitis delta virus (HDV) RNA fold into structures that are similar to each other but distinct from those of small ribozymes associated with the RNA repli-cons that infect plants. HDV ribozymes have provided a tractable system for studying the mechanism of catalytic RNA, and results of biochemical and structural studies on the HDV ribozymes, from a number of labs, have enhanced our understanding and expanded our thinking about the potential for catalytic roles of RNA side chains. The results of these studies are consistent with models suggesting that both an active-site cytosine and a divalent metal ion have catalytic roles in facilitating the cleavage reaction in the HDV ribozymes. Despite recent advances, details about the catalytic mechanism of the HDV ribozyme continue to be debated, and these ribozymes should serve as a good system for further study.

Concluding Remarks

HCV infection and subsequent hepatocarcinogenesis and HCC progression can be summarized from the perspective of receptor expression in NK cells as follows. HCV patients show increased NKG2A expression, and patients with advanced HCC display decreased NKG2D expression under the influence of sMICA. There is a link between the staged change of NK-cell phenotypes and the decreased cytotoxic activity of NK cells to HLA-E positive MICA positive hepatoma cell lines. This might have a disadvantageous effect on a living body in the ablation of transformed liver cells or the growth of tumor. It appears that apart from well-known factors from the virus viewpoint and the inflammation viewpoint, the modulation of innate immunity like this is involved in the high rate of hepatocarcinogenesis and the following progression in patients with HCV (Figure 5). In vivo, DCs are the most potent APC to activate naive T cells, but to initiate adaptive immunity in this manner, DCs should be mature and...

Prospect

Phosphorylation of S177, acetylation of K72 and methylation of R13 of S-HDAg could all modulate the replication of HDV genomic RNA from antigenomic RNA but not replication of HDV genomic RNA from antigenomic RNA. These results suggest that PTMs of S-HDAg play critical roles for its functions to facilitate the replication of HDV genomic RNA. The different requirements of S-HDAg for the replication of genomic and antigenomic RNA are also consistent with the previous suggestion that rolling circle replication of hepatitis delta virus RNA is carried out by different cellular RNA polymerase machineries (Macnaughton et al. 2002 see also the chapter by T.B. Macnaughton

HDV Disease Burden

It has been estimated that at least 15 million of the over 300 million people infected with hepatitis B virus (HBV) also harbor a hepatitis delta virus (HDV) infection and such infections can be found throughout the world (Gerin et al. 2001 Rizzetto et al. 1991). The clinical course associated with HDV is typically more severe than for HBV infection alone. Unfortunately, current therapies are largely ineffective against HDV. The study of HDV molecular virology, however, has revealed exciting new avenues for potential therapeutic intervention. After a brief review of the basic HDV virion composition and life cycle(coveredinmoredetailinother chapters in this volume),thischapter will focus on a special post-translational modification of a key HDV protein. This modification reaction, termed prenylation, turns out to be both a mechanism exploited by the virus to mediate its assembly, and the basis for an exciting new form of antiviral therapy. HDV can be viewed as a 'parasite virus' of...

Conclusions

We discussed the progress made in our understanding of the mechanisms of interferon action and interferon resistance from basic research on HCV. Chronic hepatitis C virus infection is the major cause of liver cirrhosis and liver cancer in the United States and in many developed nations. The most effective way of preventing HCV-associated liver cancer is to eradicate chronic hepatitis C virus infection from the human population by developing effective antiviral strategies. Interferon therapy is a highly effective first line of treatment available against hepatitis C virus infection. The most challenging task is to cure those chronically infected patients not responding to interferon-based therapy. Research in this area will increase our understanding of the mechanisms of interferon resistance and develop alternative strategies to treat chronic HCV infections that are IFN nonresponders.

The Virion Structure

Hepatitis Delta Envelope

The HDV virions are heterogeneous in size with an average diameter of 36 nm and a buoyant density of 1.25 g cm3 in CsCl (Fig. 1), and they display a chimerical structure consisting of an outer lipid membrane in which the HBV envelope proteins are anchored, and an inner ribonucleoprotein (RNP) made of HDV-specific elements (Bonino et al. 1984 He et al. 1989 Rizzetto et al. 1980b). The RNP includes a 1,700-nucleotide single-stranded RNA genome associated with approximately 200 copies of the HDAg protein (Gudima et al. 2002). This protein appears as two isoforms the small form (S-HDAg) of 195 amino acid residues and the large form (L-HDAg), which is 19 amino acids longer. The difference in size arises as a consequence of an RNA editing event that occurs on a replication intermediate of the viral genome and is copied onto the HDAg mRNA (see the chapter by J.L. Casey, this volume). The examination of the RNP by electron microscopy reveals a spherical, core-like structure, with no apparent...

Patients

Between January 1999 and February 2005, 391 samples, collected from HDV infected patients that were positive in a routine search of HDV RNA detection in serum, were analysed. In the first part of the study (Radjef et al. 2004), we selected 25 patients whose preliminary examination suggested that the HDV viral strains varied from previously described HDV genotypes. Indeed, we selected the 25 samples for which (1) HDV cDNA could not be amplified using previously described primers 6A and 6S (Deny 1994) even though HDV serology was positive or (2)) the RO-DNA amplicon restriction pattern was atypical (Gordien et al., unpublished results, see Fig. 2). Interestingly, 22 samples were obtained from patients from Africa or who had travelled to Africa. The male to female ratio was 0.8 and the mean age was 35 years (range, 15-53 years). Most patients had chronic active hepatitis or cirrhosis and only one patient, aged 33 years, had acute HDV superinfection.

Closing Notes

HDV superinfection of chronically HBV-infected patients results in acute, sometimes severe, hepatitis and in a high frequency of persistence of both viruses. The disease could be triggered by a HDV specific CTL response, although no data on the cellular immune response in acute HDV infection has been reported so far. Cellular immune responses (Th cells and CTLs) were found in patients with resolved HDV superinfection (without detection of HDV RNA), but not in chronically HDV-infected patients. Although these results were seen only in a small number of patients, one might conclude that a proper T-cell response seems to be the prerequisite for the elimination of HDV. This mechanism was shown for chronic HBV infection a higher frequency of HBV-specific CD8+ T-cells was detected in patients with a low level of HBV replication than in those with a high level of HBV replication (Webster et al. 2004). The HBV-specific CD8+ T-cell response was overall weak in the blood of patients with...

Perspective

The studies summarized in this chapter demonstrate that the WHV wood-chuck model of experimental chronic hepatitis infection can be applied to the analysis of aspects of the natural history of HDV infection, the development of HDV vaccine strategies, and therapeutic studies of chronic HDV superinfection. The relatively rapid progression to hepatocellular carcinoma in WHV-infected woodchucks does pose challenges for the use of this model for evaluating drug efficacy against chronic HDV disease. Further, HDV infection appears to increase the risk of hepatocellular carcinoma in patients with compensated cirrhosis type B (Fattovich et al. 2000) and the influence of chronic HDV on progression of end-stage liver disease in the woodchuck model has not been established. Indeed, many of the woodchucks in the clevudine study progressed to hepatocellular carcinoma, which precluded post-treatment follow-up studies. Perhaps these limitations can be overcome by the use of younger WHV-carrier...

Subject Index

HDAg interaction 173, 178, 179 HDV assembly 122,123 HDV infectivity 124-126 hepatitis B surface antigen (HBsAg) 114 hepatitis B virus (HBV) 114-126, 152, 156, 164-167 hepatitis delta antigen (HDAg) 27-39,92,97-102 hepatitis delta antigen long form (L-HDAg) 68,69,71,74,75, 77-80, 82-84 histone acetyltransferase (HAT) 101, 103 L-HBsAg 115-119,124-126 lamivudine 138,220,221 large hepatitis delta antigen (L-HDAg) 114, 117, 120-124, 126 linear RNA 3-5,10-12,17 small hepatitis delta antigen (S-HDAg) 114,115,120,121, 124, 162, 166, 167 subcellular localization 96, 101-103 woodchuck hepatitis virus (WHV) 212-214,221,222

Interferon System

Ifn Gamma Ifn Alpha Beta Signalling

It is believed that the interferon system is transcriptionally activated intracellularly within a few hours of virus infection through a cascade of signaling pathways that involve NF-kB, ATF2-c-Jun, and interferon-regulatory factors (IRF 3) and IRF-7 (Kawai & Akira, 2006). In humans, Type I interferons are encoded by 14 functional genes that form the interferon-alpha family. Single genes encode for interferon-beta and -omega, and three genes encodes for interferon-lambda (Sen, 2001 Bekisz et al., 2004). The biological significance of having multiple genes for interferon-alpha and only one for interferon-beta is not clear. The genes for different Type I interferons are all located together on human chromosome 9 (Diaz et al., 1994), and the Type II interferon gene is located on chromosome 12 (Schroder et al., 2004). The commercially available recombinant interferon used against HCV is interferon-a2a, interferon-a2b, or a consensus interferon (Blatt et al.,...

Michael A Morse MD Timothy M Clay PhD and H Kim Lyerly MD

In general, vaccines approved for clinical use in the United States are applied as prophylaxis against infectious pathogens, such as hepatitis B virus and pneumococcus. Generally, these vaccines must be administered prior to the onset of an infection (as primary prophylaxis) in order to be effective, although there are rare exceptions such as the treatment of rabies (in which both specific immunization and immune globulin are administered to achieve postexposure prophylaxis). In contrast, cancer immunotherapy vaccines presently are aimed at the eradication of either a microscopic or, more commonly, macroscopic burden of tumor cells.

And W Martin Kast PhD

Viruses implicated in the development of human cancer include hepatitis B (HBV) and hepatitis C (HCV) viruses, human papilloma virus (HPV), Epstein-Barr virus (EBV), human T-cell lymphoma virus, and human herpes virus 8. Together they contribute significantly to the total incidence of cancer worldwide. Current work in each of these virus systems seeks to understand the mechanisms of viral action and identify strategies of immune intervention to combat viral infection and subsequent transformation. It is thought that oncogenic proliferation may be instigated by the presence and expression of viral oncogenes, which may be integrated into the host genome. Critical viral genes may also interfere with host genes, resulting in the activation of cellular proto-oncogenes and or the inactivation of anti-oncogenes and their products. Targeting such viral proteins through various vaccination strategies offers both therapeutic and prophylactic strategies against viral induced malignancies. The...

Hepatobiliary Malignancies

Physicians and physician assistants in the GI Tumor Center at M. D. Anderson evaluated more than 900 new patients with primary or metastatic hepatobiliary tumors in 2002. Patients with primary liver cancer include those with hepatocellular carcinoma (HCC), gallbladder cancer, and intrahepatic or extrahepatic cholangiocarcinoma. Patients with liver metastases from other organ sites, most commonly colorectal adenocarci-noma, and with disease confined to the liver may be considered for surgery, tumor ablation, regional chemotherapy, or systemic chemotherapy. The initial screening evaluation of new patients includes a thorough review of outside medical records, pathologic assessment of any surgical or needle-biopsy specimens, and review of prior diagnostic CT scans and plain radiographs. Once again, a thorough history and physical examination are mandatory. In patients with liver metastases, recent assessment of the primary site of disease, such as colonoscopy for colorectal cancer, is...

Outbreak Characterization

The investigation of the hepatitis A outbreak described in Chapter 2 involved a case-control study of food items served in the restaurant. Investigators interviewed individuals with hepatitis A and controls without hepatitis A who either had dined with case patients at Restaurant R or were identified through credit card receipts as having dined at Restaurant R during October 3 through 6. They found an OR of 24.2 for consumption of mild salsa with green onions, and an OR of 5.2 for consumption of chili con queso with green onions (CDC, 2003a). An OR of 24.2 indicated that people who dined at restaurant R and subsequently developed hepatitis A were 24.2 times more likely to have eaten mild salsa with green onions than were people who dined at the same restaurant but did not develop the disease. Case-control studies depend on the ability of people to remember key historical details accurately such as what they ate. For the outbreak of hepatitis A, the investigators obtained a food...

Animal Models For The Analysis Of Innate Immune And Inflammatory Responses To Systemically Applied Ad

After systemic administration have shown that within the first minutes of intravenous virus delivery in mice, more than 99 of the infectious particles are removed from the circulation (27a,88a). Although the kinetics of virus clearance from the blood in primates (and humans) is somewhat slower than in mice, the liver remains the predominant organ in the body transduced with Ad after systemic application (2,27a,88a,140). Upon intravenous Ad administration, serum levels of IL-6 and TNF-a are increased with similar kinetics in both mice and humans (60a,141). Moreover, hepatic injury plays a key role in the pathogenesis of systemic Ad toxicity observed in mice (60a,131). It is important to note that immune responses to Ad vary significantly among different mouse strains and between different species (142). Whereas Ad-induced hepatitis following systemic vector application has been observed in all species, the dose of virus that resulted in severe toxicity (calculated as particles kg)...

TABLE 5 Extraglandular Manifestations in Primary SS

Autoimmune hepatitis primary biliary cirrhosis Diagnosis of SS also requires exclusion of other conditions that can mimic it. These include previous radiation therapy to the head and neck, amyloidosis, sarcoidosis, lymphoma, graft versus host disease, hepatitis C virus infection, HIV-diffuse infiltrative lymphocytosis syndrome, medication-induced dryness, and uncontrolled diabetes mellitus.

Materials And Methods

And DU-PAN-2 Glycoproteins 136 CCND1 136 Cyclooxygenase-2 136 Glypican-3 137 Hepatitis B XAntigen 137 HER-2 neu 138 Carcinoma 142 Hepatitis B Virus 142 Hepatitis C Virus 143 Risk Factors 143 Treatment of Hepatocellular Carcinoma 153 Natural History of Hepatocellular Carcinoma 154 Chronic Hepatitis 155 Cirrhosis 155 Phenotypic Alterations and Dysplasia 156 Emergence and Progression of Hepatocellular Carcinoma 156 Etiology of Hepatocellular Carcinoma in Humans 156 Hepatitis Viruses 157 Aflatoxins 157 Introduction 207 Epidemiology of Liver Cancer 207 Hepatitis, Liver Cirrhosis, and Liver 11 Role of Hepatitis B Surface Antigen in Hepatocarcinogenesis 229 Introduction 229 Hepatitis B Virus and Hepatocellular Carcinoma 229 Hepatitis B Virus Integration and Hepatocarcinogenesis 229 Role of Hepatitis B Surface Antigen and Hepatocellular Carcinoma 230 Detection of Hepatitis B Surface Antigen in Hepatocellular Carcinoma 230 MATERIALS 230 Immunohistochemistry 230 Southern Blot Analysis 231...

Human Subjects Research in the United States after World War

A number of studies cited by Beecher became notorious on their own. In a study of immunity to cancer at the Jewish Chronic Disease Hospital (New York), investigators injected live cancer cells into human subjects without obtaining informed consent. Another study involved the deliberate induction of infectious hepatitis (to understand better the natural history of the disease) in mentally impaired children who were residents at the Willowbrook State School for the Retarded (New York). The ethical concerns raised by this study were the

Atypical manifestations of GERD

The disease spectrum 24 we disagree with considering these manifestations as only possible complications of the NERD category, as proposed by Fass and Ofman. If, in fact, it holds true that the majority of such patients do not show esophageal mucosal damage at endoscopy, a definite proportion, between 20 and 30 of such patients do indeed have erosive or ulcerative esophagitis 25 . We too dispute that NERD and atypical'' GERD patients should be regarded as having less severe disease this is however not based on the absence or presence of mucosal damage, but on the pathogenesis of symptom perception in those patients. NERD patients are in fact possibly at least three groups of different patients (true refluxers, patients with esophageal hyperalgesia and patients with psychological disturbances) 9 , and the traditional treatment with antisecretory agents can possibly be more useful in the first group than in the others. Grouping these patients and the atypical'' ones into a single...

Special case Needlestick injury or other occupational HIV exposure

If the index patient is known, he should be tested - after relevant counselling and consent ideally the injured individual's superior should be called in immediately -for HIV antibodies, HBsAg (do not forget immunisation against hepatitis B virus if necessary), and HCV antibodies. According to the circumstances (e.g. weekend), the use of a rapid assay should be considered (see above). Often a first, preliminary decision must be made even before the test result of the index patient is available for any delay in instituting HIV post-exposure prophylaxis (HIV PEP) reduces its chances of success (CDC 2001). Therefore If there is any doubt, the first one or two doses of HIV PEP (that should be readily available day and night in the form of a so-called starter pack) should be taken and later discontinued once a negative test result becomes available It would be a mistake to start HIV PEP only once a positive result has been obtained as this will normally mean delaying the first dose beyond...

Interoperating With Other Organizations

FIGURE 5.7 Health Alert Network. a, Screenshot of an official Pennsylvania Health Advisory related to the hepatitis A outbreak described in Chapter 2. This was distributed only to Pennsylvania clinicians and alerted clinicians about an immune globulin clinic and reminded them of their need to report hepatitis A cases (CDC, 2005f). FIGURE 5.7 Health Alert Network. a, Screenshot of an official Pennsylvania Health Advisory related to the hepatitis A outbreak described in Chapter 2. This was distributed only to Pennsylvania clinicians and alerted clinicians about an immune globulin clinic and reminded them of their need to report hepatitis A cases (CDC, 2005f).

Health Care And Governmental Public Health

In addition, the workflow processes related to detection and characterization of outbreaks would be distributed optimally across both domains to maximize the efficiency and speed of the biosurveillance process. Most clinicians are capable, for example, of making observations needed to complete a case-investigation form, but at present this is a task conducted by a health department. Considerable efficiency and speed-up may be possible if IT were to enable a physician to elicit and record more epidemiologically relevant data about a patient with hepatitis A at the time the patient presents in the office setting. This level of integration is many years in the future and requires a rethinking of current systems that takes into account the potential of IT to enable conceivable, but previously impossible, configurations of organizations and workflows.

Health Issues Affecting Lgbt Populations

Of those health problems related directly to sexual behavior, HIV is currently the one most closely identified with the gay community, though it was foreshadowed by hepatitis B. The clinical and epidemiological evidence that hepatitis B was prevalent among gay men resulted in landmark hepatitis B vaccine trials in New York City in the late 70's and early 80's (Dienstag, et al., 1982 Stevens and Taylor, 1986 Szmuness, et al., 1980 Szmuness, et al., 1981). Ironically, an epidemiological study tracking the incidence of gay hepatitis B among gay men in three gay urban areas (San Francisco, New York, and Amsterdam) provided some of the earliest evidence about the emergence and progression of HIV (Hessol, et al., 1994 Van Griensven, et al., 1993). HIV has profoundly affected the LGBT community, both in terms of the unprecedented loss of community members and in terms of the community mobilization and institution-building it engendered. Despite advances in treatment and a broad-based change...

Potential Strategies For Improving The Health Of Sexual Minorities Groups In The City

Efforts to change the health behavior within the LGBT community have focused almost exclusively on preventing HIV and other STIs. Despite this emphasis, several steps whose effectiveness is well documented have not been fully taken. Salient among these is the widespread availability of sterile syringes, through exchanges and from pharmacies without prescription. This ongoing issue has HIV prevention significance for LGB who are injecting drug users, as well as for trans-gender people who use syringes to inject hormones. None of the existing syringe exchanges cater explicitly to LGB populations (though one in New York City has specific programming for transgender people). Despite extraordinarily high rates of HIV seroprevalence and the frequency of voluntary and coerced sexual behavior and drug use in prisons and jails, neither condoms nor sterile syringes are available to those incarcerated. Finally, the early conceptual divide between HIV risk due to sexual behavior and HIV risk due...

Surgery In Patients With Bleeding Tendency

Confirm the diagnosis of haemophilia, ascertain if an inhibitor is present or not, and ascertain the previous recovery levels in response to DDAVP. Is this the patient's first exposure to blood products If so, virological surveillance tests are required. Explain to the patient the risks and the benefits. Has the patient received hepatitis B vaccination Any additional problems, e.g., thrombocytopenia in HIV infected patients or abnormal liver function tests (and, therefore, prolonged PT).184185

Infections in Human Populations

To be considered as this also affects how rapidly an infection may spread in the population. One more factor which may or may not be significant is the length of the prepatient period, the time between infection and symptoms becoming apparent, as the onset of symptoms may result in relative isolation from the rest of the population. Some infections, such as herpes simplex or hepatitis B (HBV), may be symptomatic in some individuals but to a greater or lesser degree asymptomatic in others with corresponding differences shown in infectivity, and the tendency to symptomatic vs. asymptomatic infection may vary according to age, as is shown very strongly in the case of hepatitis B (Medley et al., 2001). HBV is also a good example of an infection that may manifest itself as an initial asymptomatic infection or an acute primary infection (in this case lasting a few weeks) leading to recovery or to a persistent chronic infection which for HBV may last several decades or be effectively...

Hispanic Americans

(colonias) along the Texas-Mexico border are economically as bad off or worse in some cases than third-world countries (Cuellar, 1999) and have the highest rates in the state of Texas for numerous infectious diseases such as amebiasis, hepatitis A, shigonelliosis, tuberculosis, chickenpox, and so on (Cuellar, 1999). There is also an increase in neural tube defects, particularly toward the southernmost tip of Texas along the Rio Grande River (Johnson, 1999).

Toxicity Associated With Traditional Use by Native Populations

A healthy 14-year-old adolescent girl developed nausea, vomiting, general malaise, and weight loss. Several days later she became icteric and was admitted to hospital with acute hepatitis. Drug history revealed no alcohol use two kava products and occasional ibuprofen had been used over the preceding 4 months. The packaging of the kava products was unavailable for identification purposes. Liver biopsy revealed active fulminant hepatitis with extensive necrosis and tests for viral hepatitis were negative. She underwent a successful liver transplantation and was able to return to normal activity upon recovery (34). Unfortunately, no information was provided indicating that acetaminophen toxicity had been ruled out, and the observed toxic effect could also have been associated with a large, undiagnosed acetaminophen ingestion. A 33-year-old woman took 210 mg of kava extract for 3 weeks and discontinued the product. After 2 months, she resumed taking the same product for an additional...

Changing Demography And Its Impact

The age distribution of infection is governed by the intrinsic transmissibility of the infection, by contact patterns between age groups, and by the age distribution of immunity from past infection. Thus, changes in age distribution of the population itself will impact upon the transmission dynamics of infection, perhaps in complex ways, and these in turn will impact upon the future age distribution of infection and disease and of susceptibility and immunity the ''echoes'' of such perturbations in the dynamics of infection have the potential therefore to persist for a number of years (Williams and Manfredi, 2004). The processes of infection and disease are often strongly age related, so that changes in age at infection may have important consequences for the number of deaths or cases of serious disease. Well-known examples are rubella, mumps, and poliomyelitis in which infection of young children is likely to have few long-term consequences, but infection of young adults may have...

What Should Be Clarified Beforehand

Every patient must be thoroughly questioned and examined with regard to possible concurrent illnesses before starting treatment. These must be considered when choosing a regimen. ddI is contraindicated in patients with pancreatitis. Similarly, pre-existing polyneuropathy requires that any d-drugs (ddI, ddC, d4T) be avoided. Non-insulin-dependent diabetes can become insulin-dependent on PI treatment. In such cases, the use of PIs for first-line therapy should be carefully considered. Liver disease and chronic hepatitis must also be taken into account, because the risk of developing severe hepatotoxicity on nevirapine or ritonavir is highest in these patients (Den Brinker 2000, Martinez 2001, Saves 1999, Sulkowski 2000+2002). However, a recently published study conducted in over 1,000 patients found no difference between lopinavir ritonavir and nelfinavir in patients with hepatitis C (Sulkowski 2004). 3TC or FTC and preferably also tenofovir should be incorporated into the first regimen...

Within Hostimmune System Models

The compartmental differential equation models described earlier are also adaptable to the study of the dynamics of the immune system in response to infection. Such models can provide novel and useful insights into the observed time course of quantitative clinical measures of infection within the human host and how these might relate to the probable course which may be taken by the infection by providing explanations for observed dynamical changes in such measures they also offer the prospect of illuminating some of the reasons why response to infection appears to differ between hosts. Useful examples of such work may be found in work on HIV by Nowak and Bangham (1996) and Nowak et al. (1997), and on viral hepatitis by Bocharov et al. (2004).

Tools for Manufacturing Proteins

Are limited to those that can be obtained from the cadavers of people willing to donate their organs. Some proteins can be isolated from blood. However, blood can be contaminated with viruses such as HIV, hepatitis, and, more recently, West Nile virus. Expensive screening is required to ensure safety. You can see that protein availability is limited from these sources. Thus making the desirable proteins in bacteria is an attractive option. This involves a technique known as recombinant DNA technology, or cloning, and makes possible the production of human proteins in bacteria. The DNA technology that is used to do this relies on two critically important elements restriction enzymes and plasmid vectors. Let us start with restriction enzymes.

Picornaviruses Poliovirus

Poliovirus (PV) is a nonenveloped, positive-stranded RNA virus, which is responsible for causing poliomyelitis. PV RNA is composed of a 5'-nontranslated region that contains an internal ribosomal entry site (IRES) which directs the synthesis of a single polypeptide that is subsequently processed by viral proteases into structural and nonstructural proteins (75). Polioviruses tropism is restricted to cells expressing CD155, a member of the Ig superfamily, which is prevalent on lower motor neurons resident within the spinal cord and brainstem (138). The IRES elements encode strong cell-type specific restrictions and probably play a key role in the neurovirulent behavior of the virus. It subsequently became apparent, that other viruses, such as hepatitis C virus (HCV) or rhinoviruses also contain IRES elements. Experiments into the importance of the IRES elements lead to creation of a poliovirus chimera (referred to as PV1) (139), which contained the human rhinovirus type 2 IRES element....

Other Routine Checks What Should Be Monitored

However, such guidelines or recommendations are interpreted very differently. In our experience, in cases of good immune status, unless there is a specific suspicion, routine X-rays, ultrasound examinations (exception patients with chronic hepatitis, as hepatocellular carcinoma is not rare in such cases ), multiple serologies or lactate measurements are not necessary.

Pathological Conditions

Patients with liver disease may present with signs of liver failure or complications of it, e.g., oesophageal varices, or because of biochemically detected abnormal LFTs. The latter can indicate whether the pattern of damage is hepatic (parenchymal), extra-hepatic (obstructive) or mixed in nature. Hepatic assault is typified by viral hepatitis, alcohol or drug damage and extra-hepatic disease by duct obstruction due to stones or tumour, e.g., head of pancreas. Mixed biochemical profiles are not infrequently seen in these various disorders. Needle core biopsy is interpreted in close correlation with full clinical information that includes a detailed history and wide range of investigations (see above). Its aims are to distinguish between a surgical and medical cause for the damage, and in non-neoplastic conditions to assess the degree of necroinflammatory activity that is present and the repairative response of the liver to it. It also establishes a baseline against which subsequent...

Atazanavir and Indinavir

Besides serological tests for viral hepatitis, an abdominal ultrasound should be performed to recognize structural liver dysfunction early, e.g. non-alcoholic steato-hepatitis or liver cirrhosis, before initiating HAART. Liver function should be monitored biweekly at the start of treatment with nevirapine and PIs and even more frequently in patients with pre-existing liver disease. Monthly tests are generally sufficient for all other drugs. If liver enzymes (ALT, AST) are moderately elevated (< 3.5 times ULN) in the absence of clinical symptoms, treatment can be continued under close monitoring. If liver enzymes are elevated to more than 3.5 times ULN, additional diagnostic tests should be performed, including an abdominal ultrasound. In cases of co-infection with hepatitis B or C, treatment of these conditions should be considered. With other pre-existing liver conditions, it may be useful to determine drug plasma levels. Discontinuation of treatment may not be necessary (exception...

Heat Shock Proteins As Vaccine Vehicles

The class B SR subfamily contains the CD36, SR-B and lysosomal integral membrane proteins 2 (LIMP-2) genes. The SR-B gene encodes two proteins resulting from alternative splicing of the transcript, SR-BI (CLA-1) and SR-BII (Acton et al., 1994 Murao et al., 1997 Webb et al., 1997). Class B SR are type III (multiple transmembrane domains) membrane glycoproteins. CD36 and SR-BI can form dimers and multimers (Reaven et al., 2004 Thorne et al., 1997). A leucine-isoleucine motif within the C-terminal cytoplasmic tail determines lysosomal localization of LIMP-2. CD36 is expressed on monocytes, macrophages, endothelial cells and platelets. SR-BI expression is restricted to liver, adipocytes, macrophages and DC. Class B SR recognize several non altered and altered self ligands such as native LDL, OxLDL, high density lipoproteins and very low density lipoproteins, collagen, thrombospondin and apoptotic cells (Acton et al., 1996 Calvo et al., 1998 Puente Navazo et al., 1996 Rigotti et al., 1995...

Specific infectious diseases and immunisation

Vaccinations are required for special circumstances. Yellow fever vaccination is a legal requirement for any travellers returning from a yellow fever endemic area. Cholera is not usually required. Some travellers may be exposed to tuberculosis, hepatitis, plague, rabies, typhoid, typhus, and meningococcal infection. Immunisation against these is available and recommended for those at risk. Smallpox has now been eradicated from the world and therefore smallpox vaccination is no longer required for any traveller.

Prevention of sexually transmitted diseases

Casual sexual contacts place the traveller at risk of contracting a serious, perhaps fatal, sexually transmitted disease (STD). The common STDs especially prevalent in South-East Asia and Africa are non-specific urethritis, gonorrhoea (especially penicillin-resistant strains), hepatitis B, and syphilis. HIV infection is a rapidly increasing problem, with heterosexual transmission common in Africa and in South-East Asia. Unusual STDs such as lymphogranuloma venerum, chancroid and donovanosis are encountered more commonly in tropical developing countries. A practical rule is to assume that all 'at risk' travellers are both ignorant and irresponsible and advise accordingly.

Applications of Adenoviral Vectors in Gene Expression

Hepatitis B virus surface antigen (HBsAg) has been produced from Ad-infected cells using a wide variety of strategies. In one case the HBsAg gene, driven by the MLP either with or without inclusion of TPL sequences, was inserted in place of the Ad5 El region (Davis et al., 1985), and addition of the TPL resulted in approximately a 70-fold increase in protein synthesis. As expected for expression driven by late viral regulatory elements, the appearance of HBsAg in the medium was observed at late times (10-20 hr

New nucleoside analogs

Since the development of the guanosine analog DAPD came to a halt, hopes are now focused mainly on cytidine analogs. The most promising substances are currently elvucitabine, reverset and SPD-754. Mitochondrial toxicity seems to be low, and most are effective against hepatitis B. One problem with cytidine analogs could be the combination with the cytidine analog 3TC, where a loss of efficacy seems possible. ACH-126,433 (Elvucitabine) is a nucleoside analog developed by Achillion Pharmaceuticals. It is an enantiomer of DPC 817, with the chemical name beta-L-d4FC, and is effective against HIV and HBV. In vitro studies show potency even in the presence of numerous nuke resistance mutations (Fabrycki 2003). It is also of interest as it seems to have low mitochondrial toxicity, and because of its very long halflife (Dunkle 2001). Phase II studies are underway in HIV-infected patients and in patients with hepatitis B. A small, double-blind study showed a reduction in viral load between 0.7...

Urban Services And Health

The fecal and pathogen contamination of drinking water causes diarrhea, gastroenteritis, infectious hepatitis, typhoid, paratyphoid, cholera, bacillary dysentery, amoebic dysentery, and giardiasis. Hospital records of Kathmandu city in 2003 revealed that gastroenteritis was the number two cause of morbidity in Kanti Children hospital and number one in Sukraraj Tropical Infectious Disease (STID) Hospital. The second and third causes of morbidity in the STID hospital were enteric fever and hepatitis respectively. Likewise, Hepatitis was the leading cause of mortality in STID Hospital. A hospital record survey of 2002 revealed that diarrhea (1960), typhoid (322), and hepatitis (160) were the three major diagnoses among those admitted to the STID hospital (Figure 2). Similarly, diarrhea (2036) and typhoid (170) were the major diagnoses among those admitted in Kanti Children's hospital in 2002 (Department of Health Services, 2003). Hepatitis(160) Hepatitis(160)

Clinical Manifestations

Oral hairy leukoplakia, a collection of hairy or corrugated white lesions located on the lateral surface of the tongue, is common. Sometimes splenomegaly or mild hepatitis may develop. Uncommon manifestations include heart problems, jaundice, pneumonitis, blood dyscrasia, and cerebritis (2). In patients with HIV infection, infection of epithelial cells by EBV is often represented by oral hairy leukoplakia.

Complications And Prognosis

Splenomegaly, palatal petechiae, and hepatomegaly develop in another 10 of infected patients. The main serious complication is enlarged spleen and its possible rupture. Less common complications include hemolytic anemia, thrombocytope-nia, aplastic anemia, myocarditis, hepatitis, rash, and neurologic complications, such as Guillain-Barre syndrome, encephalitis, and meningitis.

Pre Autopsy Evaluation and Analysis

Crucial clinical information can be derived from the first sentence of the history 1) a 45 year old woman, 2) a smoker, 3) seropositive for hepatitis B, 4) affected by migraine headaches, and 5) someone who had experienced multiple episodes of syncope (although the time frame is not indicated). Her presentation was suggestive for acute ischemic heart disease. The quality and characteristics described are very specific for coronary pain ( 95 specificity, and a high positive predictive value). Electrocardiograms at first revealed ST segment elevations in II, III, and avF and then diffuse ST elevations across the precordium. Her death was rapid, and it was not associated with cardiac enzyme increases. Thus, we are trying to establish the cause of apparent ischemic heart disease in a relatively young woman. Several questions about this case can easily be raised

Development of New Drugs

An analogous pair of opposing consequences are envisaged with respect to development of new drugs. One position argues that the next generation of modern medicines will never get out of research labs if efforts to halt the patenting of genes are successful (Feldbaum, 1996, p. 10). This view is supported with evidence taken from other areas of biomedical technology, where patents have been granted for blood clotting agents for hemophiliacs, products for breaking up blood clots, a vaccine for Hepatitis B, along with numerous other drugs and diagnostic products (Feldbaum, 1996). The opposing position contends that the extraordinary advances in biomedical knowledge and technology in the past 40 years have been largely a result of public funding of biomedical research (King, 1996).

RNAi In Clinical Cancer Therapy

In concept, diseases such as cancer, which are characterized by overexpression or aberrant activation of specific oncogenes, are suitable candidates for nucleic acid-based gene-silencing therapies. Several nucleic acid drugs that are based on ODNs were under clinical trials and Vitravene (sodium fomivirsen) has been used for the treatment of cytomegalovirus (CMV) infection of the eye in clinics (2,3,5). Several ribozyme-based phase I II clinical trials are in early-phase of clinical evaluation for patients with breast cancer, colon cancer, and hepatitis (3). The problems of toxicity and poor clinical efficacy with antisense and ribosome molecules remain to be solved even after more than a decade of drug development attempts. Although the term RNAi was coined just 6 yr ago (23) and the application of siRNAs in mammalian cells was started only three years ago (27,28), RNAi is rapidly taking center stage of the development of nucleic acid-based therapeutics. siRNA-based biotechnology...

Integration of Expression Vectors into the P pastoris Genome

An alternative integration strategy is available with P. pastoris expression vectors that contain an additional fragment derived from sequences 3' of the AOX1 gene (Fig. 2) (Cregg et al., 1987). These vectors can be cut with selected restriction enzymes that release the expression cassette (i.e., the fragment containing the promoter, foreign gene, and terminator) and HIS4 gene on a DNA fragment flanked by AOX1 5' and 3' terminal sequences. Approximately 10-20 of His+ transformation events with these vector fragments are the consequence of a gene replacement event in which the AOX1 gene is deleted and replaced by the expression cassette and HIS4 gene (Fig. 4B). The resulting strains are forced to rely on the transcriptionally weak AOX2 gene for growth on methanol and, as a result, metabolize methanol at a greatly reduced rate. These gene replacement strains are easily identified among His+-transformed colonies by replica plating them to methanol and selecting those with reduced ability...