Astrovirus associated acute gastroenteritis in western India: Predominance of dual serotype strains

A five-year (2004-2008) study was conducted on patients with acute gastroenteritis from different cities of Maharashtra, western India to detect and characterize astrovirus infections. A total of 1340 fecal specimens were collected from sporadic cases that included 1240 children (≤8 years) and 100 adults (18-70 years) from Pune, Aurangabad and Nagpur cities. All specimens were subjected to astrovirus specific RT-PCR followed by sequencing and phylogenetic analysis. The overall positivity to astrovirus was found to be 3.1% with highest number of infections in winter months. A high prevalence of astrovirus was observed in children ≤1 year of age. Phylogenetic analysis of the partial ORF1a (serine protease) and ORF2 (capsid gene) regions showed the circulation of three probable recombinant types with different ORF1a/ORF2 specificities (HAstV-8/HAstV-1, HAstV-7/HAstV-2, HAstV-4/HAstV-5) along with HAstV-8 of a single specificity in the study population. HAstV-8/HAstV-1, specificity predominated (67.7%) in the region followed by HAstV-7/HAstV-2 (9.7%), HAstV-4/HAstV-5 (6.5%) and HAstV-8 (16%) types. This is the first report that highlights the genetic diversity of astrovirus strains circulating in Maharashtra state, western India.