Detection and characterization of hepatitis B virus strains from wild-caught gorillas and chimpanzees in Cameroon, Central Africa.

Previous epidemiological studies have reported a high prevalence of hepatitis B virus (HBV) infection in chimpanzees in Gabon and Congo, Central Africa. There is no data for this species from Cameroon. To date few cases of active HBV infection have been documented in gorillas and only one complete HBV sequence has been described from a wild-caught gorilla originating from Cameroon and housed in Germany. Since gorillas are apes found in Cameroon, we thus investigated the prevalence and genetic relationships of HBV infecting apes in this area. We subjected 185 wild-caught apes' plasmas, including 159 from chimpanzees and 26 from gorillas to ELISA screening for HBV surface antigen (HBsAg). Subsequently, we detected HBV DNA, sequenced the whole HBV genome and performed phylogenetic analysis. Eleven (6.9%) chimpanzees and 3 (11.6%) gorillas plasma were found HBsAg positive, of which 8 and 3 were positive for HBV DNA, respectively. Phylogenetic analyses revealed that the 3 new gorilla HBV sequences grouped together with the single available HBV sequence from gorilla. Evidence of recombination between HBV Pan troglodytes troglodytes and Pan troglodytes vellerosus was observed in two of the Cameroonian strains. Findings from our study show that HBV infection is endemic in wild-born gorillas and chimpanzees in Cameroon, and that there is evidence of recombination between HBV strains circulating in chimpanzees. We demonstrated the existence of gorillas' specific HBV strains distinct but related to those found in chimpanzees living in the same habitat in Cameroon, providing substantial evidence of species association of HBV in NHPs.