Novel hepatitis B virus strain from a chimpanzee of Central Africa (Pan troglodytes troglodytes) with an unusual antigenicity of the core protein

We and others have previously reported a hepatitis B virus (HBV)-like hepad navirus strain which seemed to be indigenous to West African chimpanzees (P an troglodytes verus). After that, we obtained an HBsAg-positive serum samp le from a chimpanzee from Central Africa, named Bassi, belonging to another subspecies (P. troglodytes troglodytes). The full-genome nucleotide sequen ce of the hepadnavirus from Bassi showed a significant difference (9-26%) f rom those so far reported from primates including humans, chimpanzees and g orillas, suggesting a novel strain. More interestingly, however, the core a ntigen (HBcAg) deduced from Bassi's sequence showed only 78-82% similarity to known primate strains at the amino acid level, whereas the other strains shared more than 90% similarity. HBcAg ex-pressed from Bassi HBV failed to react with monoclonal antibodies that were directed at an epitope borne by codons 135-145 of HBcAg of conventional hepadnaviruses. This could explain why Bassi was negative for anti-HBc in a routine test. Here we report the novel HBV strain presumably indigenous to P. troglodytes troglodytes in Cen tral Africa. Copyright (C) 2001 S. Karger AG, Basel.