Further evidence of hepatitis B virus genotype I circulation in Northeast India

Hepatitis B virus (HBV) genotypes have known to show a geographical pattern in their distribution and have been used to trace the migration of populations from geographically distant regions. Novel recombinants between HBV genotypes A, G and C referred as genotype I has been recently reported from Eastern India. In our investigation to characterise antiviral resistance mutations, we identified a rare case of HBV genotype I infection in chronic hepatitis B subject. We encountered confounding results of this emerging genotype 'designated as genotype G' in three widely used HBV sequence database for genotype determination. The recombinant fragment of genotype G largely occupies the surface gene sequence of the newly identified genotype I and could hence lead to misclassification of genotype I. Additionally, recombination analysis of the generated sequences in Simplot and jpHMM model showed two different patterns of recombination events. In conclusion, the increasing recognition of genotype I in this population suggests that further studies may reveal uncommon genotypes from other geographically distant regions. Our observation of potential genotype I misclassification despite the use of public HBV sequence database and other recombination analysis tools highlights the need for updating and validating public sequence domains of diagnostic importance.