Identification of recombination between subgenotypes IA and IB of hepatitis A virus.

Co-circulation of subgenotypes IA and IB of hepatitis A virus (HAV) has been reported in South Africa, South America, Europe, and the United States. In this study, phylogenetic and recombination analyses were performed for the first time on 31 complete HAV genomes from infected humans and simians. Three potentially significant intra-genotypic recombination events (I-III) were identified by recombination detection analysis. Recombination events I and II occurred between the lineages represented, respectively, by the Japanese isolate AH2 (AB020565, subgenotype IA) and the North African isolate MBB (M20273, subgenotype IB), giving rise to the recombinant Uruguayan isolate HAV5 (EU131373). Recombination event III occurred between the lineages represented, respectively, by the North African isolate MBB (M20273, subgenotype IB) and the German isolate GBM (X75215, subgenotype IA), resulting in the Italian isolate FG (X83302). The findings demonstrate that humans can be co-infected with different HAV subgenotypes and provide valuable hints for future research on HAV diversity.