Detection of Genogroup I and II human picobirnaviruses showing small genomic RNA profile causing acute watery diarrhoea among children in Kolkata, India

Abstract

Picobirnaviruses (PBVs) with bisegmented small RNA genome profile (1.75 and 1.55 kbp for segment 1 and 2, respectively) were detected from 1999 to 2003 in faecal specimens of acute watery diarrhoea cases, largely children ( n = 20) and an adult in Kolkata, India. Varying degrees of dehydration necessitated their visit to hospital for further treatment and management of acute watery diarrhoea. PBV was associated with rotavirus ( n = 3) or astrovirus ( n = 3) and with both in one case. No co-infection with norovirus, sapovirus or adenovirus was detected in the picobirnavirus positive cases. No co-infection with parasites ( Cryptosporidium spp., Giardia spp., Entamoeba spp., helminths) or bacteria ( Vibrio spp., Shigella spp., Escherichia coli) was detected among the picobirnavirus positive cases. There was a single instance of co-infection with Salmonella spp. ( n = 1). PBVs not associated with serious diarrhoea illness and showing large genome profile (2.3–2.6 and 1.5–1.9 kbp for segment 1 and 2, respectively) have earlier been reported in adult individuals and recently among children from a slum community in Kolkata, India. The short genome profile PBVs associated with acute watery diarrhoea may be another emerging diarrhoeagenic virus in Kolkata, India. Molecular characterization using reported primers PicoB25–PicoB43 for Genogroup I and PicoB23–PicoB24 for Genogroup II in RT-PCR showed the presence of Genogroup I PBVs ( n = 6) and Genogroup II PBVs ( n = 5), while some could not be amplified ( n = 3) with these primers. Sequence analysis of Genogroup I amplicons indicated remarkable sequence heterogeneity. After more than a decade, four PBV positives of Genogroup II were detected during this study. Phylogenetic analysis showed varying degree of genetic diversity amongst PBV strains from Kolkata and other countries.