AIM:To determine whether one genotype(A or non-Agenotypes of HBV)predominated over the other during thecourse of HBV infection.METHODS:Four baboons were inoculated with HBV.DNAwas extracted from serum obtained at monthly intervals post-inoculation for 52 weeks and HBV DNA was amplified usingprimers specific for the core region containing an insertcharacteristic of genotype A(nt 2 354-2 359,numberingfrom the EcoRI site).The amplicons were cloned into PCR-Script~(TM)and a minimum of 15 clones per time point weresequenced in both directions.RESULTS:Both genotypes persisted for the entire follow-up period of 52 weeks.Genotype non-A predominated intwo baboons and genotype A in one baboon.Neithergenotype predominated in the fourth baboon,as shown ata 5%level of testing.CONCLUSION:No conclusions concerning the dominanceof either genotype or the natural progression or replicationrates of HBV could be drawn because the pattern of thegenotypes found may have been caused by samplingfluctuations at the time of DNA extraction and cloning as aresult of the very low viral loads in the baboon sera. AIM: To determine whether one genotype (A or non-Agenotypes 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 character of genotype A (nt 2 354-2 359, numbering from the EcoRI site). The amplicons were cloned into PCR-Script ™ (TM) and a minimum of 15 clones per time Both were sequenced in both directions .RESULTS: Both genotypes were persisted for the entire follow-up period of 52 weeks. Genotype non-A predominated intwo baboons and genotype A in one baboon. Neither genotype predominated in the fourth baboon, as shown ata 5% level of testing.CONCLUSION: No conclusions concerning the dominance of either genotype or the natural progression or replicationrates of HBV could be drawn because the pattern of the genotypes found may have been caused by sampling fluctuations a t the time of DNA extraction and cloning as aresult of the very low viral loads in the baboon sera.