Identification of hepatitis B virus indigenous to chimpanzees

Hepatitis B viruses (HBV) and related viruses, classified in the Hepadnavir idae family, are found in a wide variety of mammals and birds. Although the chimpanzee has been the primary experimental model of HBV infection, this species has not been considered a natural host for the virus. Retrospective analysis of 13 predominantly wild-caught chimpanzees with chronic HBV infe ction identified a unique chimpanzee HBV strain in 11 animals. Nucleotide a nd derived amino acid analysis of the complete HBV genome and the gene codi ng for the hepatitis B surface antigen (S gene) identified sequence pattern s that could be used to reliably identify chimpanzee HBV. This analysis ind icated that chimpanzee HBV is distinct from known human HBV genotypes and i s closely related to HBVs previously isolated from a chimpanzee, gibbons, g orillas, and orangutans.