Comparative genomics of hepatitis A virus, hepatitis C virus, and hepatitis E virus provides insights into the evolutionary history of Hepatovirus species

Wassenaar, Trudy M.; Jun, Se-Ran; Robeson, Michael; Ussery, David W.

Finally, because of lack of sequence similarity between the various virus species, the amino acid composition of their proteomes was compared, as this is even less dependent of nucleotide composition than codon usage preference is. Again, this comparison segregated the analyzed virus proteomes into two groups, one containing virus species with an amino acid frequency more HAV-like and the other group more resembling HCV and HEV ( Figure 6 ) In all analyses presented here, HCV and HEV group together, although these virus species do not share sequence similarity and are not classified in the same taxonomic families (Table 1) . A structural similarity between HEV and Caliciviridae (to which norovirus belongs) has been noted before (Bradley, 1990) , but it is apparent that HCV also bears resemblance to Flaviviridae, as not only exemplified by HCV but also by the other Flaviviridae included here (HPgV, Zika virus and WNV).