Evolutionary analysis of rotavirus G1P[8] strains from Chennai, South India

Abstract

Rotaviruses by virtue of its segmented genome generate numerous genotypes. G1P[8] is the most common genotype reported globally. We intend to identify the evolutionary differences among G1P[8] strains from the study with vaccine strains. Stool samples collected from children <5 years were screened for rotavirus antigen by enzyme linked immunosorbent assay. The samples that tested positive for rotavirus were subjected to VP7 and VP4 semi‐nested RT‐PCR. Sanger sequencing was performed in randomly chosen VP7 and VP4 rotavirus strains. Phylogenetic analysis showed less homology between study strains and vaccine strains and they were placed in different lineages. The VP7 and VP4 proteins of rotavirus were analyzed by two different platforms to identify the amino acid substitutions in the epitope regions. Nine amino acid substitutions with respect to Rotarix®, RotaTeq® and Rotasiil®—V66A, A/T68S, Q72R, N94S, D100E, T113I, S123N, M217T, and I281T were observed in VP7. There were five amino acid substitutions—S145G, N/D195G, N113D, N/I78T, E150D in VP4 (VP8 portion) with respect to Rotarix® and RotaTeq® vaccine strains. M217T substitution in VP7 (epitope 7‐2) and N113D, D195G substitution in VP4 (epitope 8‐3, 8‐1) confer changes in polarity/electrical charge with respect to vaccine strains, thus indicating the need for continued surveillance.

Epidemiology of major entero-pathogenic viruses and genetic characterization of Group A rotaviruses among children (≤5 years) with acute gastroenteritis in eastern India, 2018–2020

“…Though there is no proper evidence of compromised vaccine efficacy as a result of amino acid substitutions at the aforementioned epitopes, few studies have highlighted that pre-existing antibodies that block amino acid residues 94, 213 and 217 of G1 type of rotaviruses are protective in case of re-infection with a more virulent rotavirus strain (Green & Kapikian, 1992;O'Ryan et al, 1994). Substitutions at these sites, participating in antibody recognition, have also been found in G1 strains sequenced from South India (Selvarajan et al, 2021), Brazil (Maranhão et al, 2012), Lebanon (Harastani et al, 2020a;Harastani et al, 2020b) and South Africa . Glycosylation is frequent at asparagine residue, and hence, the substitution of serine by asparagine at position 94 might affect the immunogenicity of 7-1a epitope (Caust et al, 1987)), although both the amino acids are polar, uncharged in nature.…”