Shilpi Srivastava

Aetiology of childhood viral gastroenteritis in Lucknow, north India

Background & objectives: Due to limited availability of data on viral aetiology of acute gastroenteritis in north India, the present study was planned to detect rotavirus, norovirus, sapovirus and astrovirus in stool samples of both in hospitalized and non-hospitalized children less than five years of age presenting with acute gastroenteritis. Methods: A total of 278 stool samples from equal number of children were tested for rotavirus antigen using ELISA and for norovirus, sapovirus and astroviruses by reverse transcription (RT)-PCR. Results: Of the 169 samples from hospitalized patients, rotavirus, norovirus, sapovirus and astrovirus were detected in 19.5, 2.3, 3.5 and 2.9 per cent samples, respectively. Of the 109 samples collected from the non-hospitalized patients, frequency of rotavirus and sapovirus detection was 9.1 and 1.8 per cent, respectively while norovirus and astrovirus were not detected. Interpretation & conclusions: Rotavirus was the most frequent cause of viral gastroenteritis in both hospitalized and non-hospitalized children. Maximum positivity of the viruses was seen in children less than two years of age.

Rotavirus Nonstructural Protein 4 (NSP4)-Viral Enterotoxin with Multiple roles in Pathogenesis of Diarrhoea in Children -

Nonstructural protein 4 (NSP4) of Rotavirus has been designated as the first viral enterotoxin. Its role in viral replication is already well known. Intensive research over the past decade has shown the involvement of this protein in many cellular activities both in ‘expressed’ as well as ‘secreted’ form. It is responsible for increased intracellular calcium levels in the infected cell leading to a cascade of events which involve phospholipase C mediated secretion of Chloride ions. NSP4 also inhibits intestinal disaccharidases and sodium glucose symporter(SGLT1) so that complex sugars are retained resulting in malabsorption. It also alters actin in the villi resulting in their flattening and overall decreased absorptive area. NSP4 is associated with extracellular proteins and is hypothesized to have paracrine effects on neighbouring cells. Recent research has found it to be an activator of enteric nervous system too. All these factors contribute to the pathogenesis of diarrhoea which looks multifactorial and certainly very different from the bacterial toxin mediated diarrhoeas of E. coli and V. cholerae. We still don’t have the final word on this intriguing protein which is now a potential candidate for a vaccine against rotavirus. The aim of this review is to put forward the salient features of the research done to elucidate the functions of NSP4.

Molecular characterization of the rotavirus enterotoxin NSP4 gene of strains causing diarrhoea in children aged 0-5 years in northern India

Non structural protein 4 (NSP4) gene of Rotavirus encodes a multifunctional protein which has significant role in viral multiplication and pathogenesis of acute watery diarrhoea associated with rotaviral gastroenteritis. It is known as the first viral enterotoxin and mutations of the gene have been linked to altered pathogenesis. This study was planned to ascertain the genotypes and genetic variations of NSP4 gene in the rotavirus strains prevalent in this area. We collected consecutive diarrhoeal stools from equal no of children aged under five years hospitalized with diarrhoea in a period from January 2010 to June 2012 and tested them for rotavirus antigen by ELISA. NSP4 gene was amplified by RT-PCR and subsequently sequenced (Big-Dye terminator kit using 3130 ABI, Genetic analyzer) and genotyped by Rotavirus C software. Of the 260 samples, 58(22.3%) samples were positive by ELISA. We were able to amplify NSP4 gene by RTPCR from 45 strains of which 35 amplicons were selected for sequencing. Total 25(71.4%) strains belonged to genotype E1, 6 (17.1%) strains to genotype E2 and 4 (11.4%) matched with the genotype E6. Sequence analysis revealed changes in the nucleotides causing punctate mutations in the conserved regions, the Inter species variable domain (ISVD) and the enterotoxin region (amino acid 114-135). On evolutionary analysis of 33 strains amino acid at position 131 was found under positive selection.