Molecular Analysis of VP7 Gene of Rotavirus G1 Strains Isolated from North India

Rotavirus G1 strains are the predominant cause of diarrhoea in children. Universally common rotavirus vaccines (Rotarix and RotaTeq) include G1 as the immunological component. India has recently introduced rotavirus vaccine in Universal Immunization Programme. Therefore, in the present study, VP7 gene of rotavirus G1 strains circulating in Himachal Pradesh, India is analysed to study their phylogenetic characteristics, and further comparative analysis was performed for assessment of their divergence from the vaccine strains. The rotavirus strains (JU-SOL-5, JU-SOL-58, JU-SOL-77, JU-SOL-173 and JU-SHI-14) analysed in the study were isolated from the faeces of diarrhoeic children during active surveillance for rotaviruses. The Himachal strains clustered together in G1-Lineage 1 in the phylogenetic analysis. All five isolates showed 96.4-98.8 % similarity with the other G1-Lineage 1 strains at amino acid level. However, none of them clustered in the pre-defined sublineages within lineage 1. Interestingly, all the strains were distantly related to the vaccine strains having 93.9-94.5 and 91.9-92.6 % similarities at amino acid level with Rotarix and RotaTeq strains, respectively. The comparative sequence and structural analysis of the Himachal strains with vaccine strains revealed differences in amino acids in epitope region of the protein especially at the antibody neutralization sites. The study highlights variations between the G1 strains from Himachal Pradesh, India and Rotarix and RotaTeq vaccine strains. These differences might have an impact on the neutralization efficiency of vaccine and subsequently on vaccine efficacy. This underscores further investigation to study intragenotype antigenic variability and also impact of viral evolution on vaccine effectiveness.