FULL-LENGTH GBV-C HGV GENOMES FROM 9 JAPANESE ISOLATES - CHARACTERIZATION BY COMPARATIVE ANALYSES/

The genomes of nine GBV-C/HGV isolates from Japanese chronic hepatitis patients were fully sequenced and characterized. They shared 85% nucl eotide sequence homology with previously characterized isolates from t he US and West Africa. Homology studies and phylogenetic analyses show ed that the Japanese isolates formed a third group distinct from the e stablished groups 1 and 2. The genetic distances between the three gro ups of GBV-C/HGV were very similar to the distances between the two cl assical swine fever virus (CSFV) serotypes, which suggested that they might belong to a separate GBV-C/HGV serotype. Plot similarity analysi s comparing the three groups exposed relatively conserved terminal non -coding regions. Hairpin structures predicted in the Japanese isolates are probably involved in viral replication. The region coding E1-E2-N S-2 showed the least similarity (80%); in HCV the similarity here is o nly 50% due to its hypervariablity. NS-3 and NS-5b that respectivity e ncode the helicase/protease and RNA-dependent RNA polymerase, had a hi gh degree of amino acid homology, suggesting a high degree of function al constraint in this region. The NS-Sb nucleotide sequence was highly conserved perhaps because of constraints from RNA secondary structure and/or an open reading frame in the negative strand.