Characterisation of rotavirus strains identified in adolescents and adults with acute gastroenteritis highlights circulation of non-typeable strains: 2008–2012

Abstract

BackgroundGroup-A Rotavirus (RV) is the main causative agent of acute gastroenteritis in children < 5 years of age. Its role as a pathogen in adults needs to be monitored. The aim of this study was to characterise the group-A RV strains that cause infections of acute gastroenteritis in adolescents and adults and determine the temporal variations in the circulating strains during 2008–2012 in continuation of an earlier study conducted in 2004–2007, in Pune, India. MethodsA total of 371 stool samples were tested by RV antigen capture ELISA. VP4, VP6, VP7 and NSP4 genes of all of the RV strains detected in the study were analysed using reverse transcription PCR, multiplex PCR and sequencing. ResultsGroup-A RV was detected in 9.4% (35/371) of the stool samples examined in the study period. The frequency of detection of RV was found to decline from 18.0% (16/90) in 2008 to 3.8% (2/52) in 2012. Of the 6 strains typed for both VP7 and VP4 genes, G2P[4], G1P[8] and G9P[4] were detected in 3, 1 and 2 samples, respectively. Sequencing and phylogenetic analysis of the VP4, VP6, VP7 and NSP4 genes revealed an infrequently reported NSP4-E6 genotype and circulation of heterogenous [G2 (lineage IIC and IID), G9 (lineage 3), P[4] (lineage P[4]-5), P[8] (lineage P[8]-3), VP6 I1 / I2 and NSP4 E2] genotypes/lineages in the RV strains. Analysis of linkage within these genes showed concordance (G2-P[4]-I2-E2) and discordance (G9-P[4]-I2-E6), equally. The sequences of amplified VP6 (n = 20) and NSP4 (n = 2) genes from G and P nontypeable RV strains (80.0%, 28/35) were most homologous to human group-A RV strains. ConclusionThe study underscores the significant temporal variations in RV strains, identifies circulation of intergenogroup reassortants among adolescent and adult patients with acute gastroenteritis and emphasizes the need for continued surveillance and whole genome analysis of emerging rotavirus strains.