Coepidemiological Speciation of HBV and HDV

One of the main difficulties to characterize both HBV and HDV in the same sample is the inhibition of the HBV replication in the case of HDV co- or superinfection. However, using sensitive approaches it is now possible to obtain such information. An alternative would be to extract both RNA and DNA from the liver tissue when available. Analyses of Amazonian isolates clearly identify a strong association between HBV/F and HDV genotype III (Casey et al. 1996; Nakano et al. 2001; Quintero et al. 2001). HDV-1, which is ubiquitous, is mainly associated with HBV/D around the Mediterranean region (Saudy et al. 2003; Bozdayi et al. 2004), Russia (Flodgren et al. 2000) and has recently been described in Mongolia (Inoue et al. 2005). However, HDV-1 has also been found together with HBV/A and, in Taiwan, with HBV/B and HBV/C (Kao et al. 2002). HDV-2, which corresponds to the first Japanese prototype lineage and the Yakutian lineage, is also linked with Asian HBV genotypes (HBV/B and HBV/C) (Kao et al. 2002). Interestingly, HDV-4 (previously genotype IIb)

is associated with HBV/B (Moriyama et al. 2003) and might be comprised of two subgroups of Taiwan and Okinawa HDV strains (Watanabe et al. 2003). HDV clades 5 to 8 are associated with HBV African strains mainly HBV/E and HBV/A (P. Deny, unpublished results).

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