Among enteric viruses, rotavirus A (RVA), norovirus (NoV), adenovirus, and astrovirus (AstV) are the major etiological agents associated in acute gastroenteritis. The present study highlights, clinical, epidemiological, and molecular aspects with respect to RVA, NoV, enterovirus (EV), and human parechovirus (HPeVs) in sporadic cases (n = 305) of acute gastroenteritis, Pune (Maharashtra), Western India. Detection of RVA was carried out by enzyme-linked immunosorbent assay, NoV, EV, and HPeVs by reverse transcription PCR. Prevalence of 36.06%, 20.32%, 14.09%, 3.93%, respectively was observed for RVA, EV, HPeVs, and NoV along with coinfections. Infections occurred in children less than 2 years old, with peak infections within 12 months age. The disease severity in RV infections was found high (70.90%) with severe disease, followed by EV (62.9%), NoV (58.33%), and HPeV (44.58%). Predominant strains of RV G1P[8], G2P[4] types with unusual G9P[4], NoV Genogroup II of genotype 4 strains and multiple EV types with EV-B species, E14 and E17 and two novel EV-75, EV-107 types were detected. Circulation of heterogeneous HPeV genotypes (HPeV1-5, 7, 8, 13, 14, 16) with predominance of HPeV-1 was noticed. Changing trends in circulation of a rare HPeV-2 genotype, with emerging and reemerging strains was noted. The study highlights association of RVA, NoV, EV, and HPeV and their mono-infections, genotype distribution, and changing trends in acute gastroenteritis, and added more knowledge on rota and nonrota enteric viruses in acute gastroenteritis. More such studies in rota vaccinated era are required across the country, as Indian rotavirus vaccine has been implemented under the National Immunization program.

Astroviruses (AstV) are associated with enteric and systemic disease in mammals and birds. Astroviruses have received increased attention recently as they have been found to be associated with sporadic neurologic disease in mammals including humans. In pigs, porcine astrovirus (PoAstV) can be widely detected and has been grouped in five genotypes (PoAstV1 to PoAstV5). In the present study, we detected multiple PoAstVs in serum samples, nasal swabs, and fecal swabs collected from pigs suffering from respiratory disease or diarrhea but also from asymptomatic pigs, indicating a wide tissue tropism of the identified PoAstV genotypes. Coinfection of different genotypes in the same pig was commonly observed, and within an individual pig a high genetic diversity was observed for viruses belonging to the same PoAstV genotype. Two complete genomes of PoAstV2-WG-R2/2017 and PoAstV4-WG-R2/2017 were successfully obtained and characterized, with genome sizes of 6396 and 6643 nucleotides, respectively. The PoAstV2-WG-R2/2017 genome showed identities of 67.2-77.4% to other known PoAstV2 genomes, and the PoAstV4-WG-R2/2017 genome showed identities of 72.8-80.5% to other known PoAstV4 genomes. The predicted spike domain of open reading frame 2 (ORF2) of these strains showed the highest genetic heterogeneity, with amino acid identities of 13.7-70.9% for PoAstV2-WG-R2/2017 to other known PoAstV2 strains, and identities of 24.4-63.3% for the PoAstV4-WG-R2/2017 to other known PoAstV4 strains. Possible recombination events were identified in each of the two sequences. Two subclades of PoAstV2 and three subclades of PoAstV4 were defined in the present analyses. The obtained data provide further evidence for extraintestinal infectivity of PoAstVs, and confirmed the high genetic diversity of PoAstVs and the coinfection potential of different PoAstV types in a single pig.