Analysis of two genomic variants of orang-utan hepadnavirus and their relationship to other primate hepatitis B-like viruses.

We recently described orang-utan hepadnavirus (OuHV) (Warren et al., Journal of Virology, 73, 7860-7865, 1999). Phylogenetic analyses indicated that the various isolates of OuHV can be divided into two genomic variants. Two representatives from each genomic cluster were analysed both molecularly and phylogenetically. Their genome organization was highly similar to other hepadnaviruses of apes and humans. The complete genome sequences of the two OuHV types had an overall 5% sequence difference. Research on 25 seropositive Bornean orang-utans showed that, of the 19 animals infected with one variant, 12 originated from East Kalimantan. Phylogenetic analysis was performed using the full-length genomes of various primate hepadnaviruses. The tree topology revealed one cluster of Old World hepadnaviruses that is divided into two subclusters, one consisting of the ape viruses, and the other comprising the human genotypes A-E. These data suggest that the great apes and gibbons have been infected with a common ancestor hepadnavirus.