Follow up of infection of chacma baboons with inoculum containing a and non-a genotypes of hepatitis B virus

Abstract

AIM: To determine whether one genotype (A or non-A genotypes of HBV) predominated over the other during the course of HBV infection. METHODS: Four baboons were inoculated with HBV. DNA was extracted from serum obtained at monthly intervals post-inoculation for 52 weeks and HBV DNA was amplified using primers specific for the core region containing an insert characteristic of genotype A (nt 2354-2359, numbering from the EcoRI site). The amplicons were cloned into PCR-Script^TM and a minimum of 15 clones per time point were sequenced in both directions. RESULTS: Both genotypes persisted for the entire follow-up period of 52 weeks. Genotype non-A predominated in two baboons and genotype A in one baboon. Neither genotype predominated in the fourth baboon, as shown at a 5% level of testing. CONCLUSION: No conclusions concerning the dominance of either genotype or the natural progression or replication rates of HBV could be drawn because the pattern of the genotypes found may have been caused by sampling fluctuations at the time of DNA extraction and cloning as a result of the very low viral loads in the baboon sera.