Detecting putative recombination events of hepatitis B virus: An updated comparative genome analysis

Hepatitis B virus subgenotyping: history, effects of recombination, misclassifications, and corrections

Hepatitis B virus (HBV) has evolved into phylogenetically separable genotypes and subgenotypes. Accurately assigning the subgenotype for an HBV strain is of clinical and epidemiological significance. In this paper, we review the recommendations currently employed for HBV subgenotyping, the history of HBV subgenotyping, the effects of recombination on HBV subgenotyping, misclassifications in HBV subgenotyping, and suggestions are made to correct the misclassifications. Finally, proposals are made to guide future HBV subgenotyping.

Identification of novel inter-genotypic recombinants of human hepatitis B viruses by large-scale phylogenetic analysis

Recombination plays an important role in the evolutionary history of Hepatitis B virus (HBV). We performed a phylogenetic analysis of 3403 full-length HBV genome sequences isolated from humans to define the genotype. The genome sequences were divided into 13 sub-datasets, each approximately 250 bp in length. Genotype designations obtained from the sub-datasets that differed from the genotype defined by the whole genome were assigned as putative recombinants. Our results showed that 3379 out of 3403 sequences belonged to the previously described and putative genotypes A to J respectively, with 315 sequences defined in this analysis. The remaining 24 viruses had sequence divergence of less than 8% with both genotypes B and C and were provisionally assigned genotype "BC". 1047 out of 3403 sequences were identified to be putative recombinants, of which 72 were identified to be novel recombinants. Notably, all viruses of the herein described genotype "BC" were identified to be B/C recombinants.