Polymorphism of rotavirus genotype G1 in Brazil: in silico analysis of variant strains circulating in Rio de Janeiro from 1996 to 2004

The polymorphism of species A rotavirus genotype G1 strains (RVA-G1) circulating in Rio de Janeiro between 1996 and 2004 was evaluated. The VP7 encoding gene of 36 G1 isolates was sequenced and compared to references strains. The deduced amino acid sequences were used as basis for in silico analysis of the VP7 protein. We observed the circulation of two major G1 lineages and five sublineages during the studied period. Comparison between the VP7 trimeric structures of a rotavirus vaccine strain and Brazilian G1 strains showed mutations at amino acid residues located at the calcium binding site and at several neutralizing antibody recognition sites. Although the rotavirus vaccine program has clearly been successful in Brazil, these results suggest the possibility of the emergence of G1 strains that could evade the immune response elicited by a RVA vaccine and cause a vaccine breakthrough. Consequently, continuous monitoring of rotavirus intragenotypes diversity is critical to understand how it could affect vaccine effectiveness.