POLYMERASE CHAIN-REACTION DETECTION OF SMALL ROUND-STRUCTURED VIRUSESFROM 2 RELATED HOSPITAL OUTBREAKS OF GASTROENTERITIS USING INOSINE-CONTAINING PRIMERS

Two outbreaks of gastroenteritis in the UK which occurred nine days ap art at Lymington and Southampton hospitals were investigated. The clin ical and epidemiological features of both outbreaks were characteristi c of small round-structured virus (SRSV) infection with rapid onset of diarrhoea and/or nausea and vomiting and propagation of the outbreaks by secondary spread. SRSV particles were observed by immune electron microscopy (EM) in 60% of faecal samples from both outbreaks and no ot her pathogens were detected. The index case for the second outbreak wa s a patient who was admitted with diarrhoea and vomiting after being d ischarged from Lymington hospital during the first outbreak. The possi bility that the two outbreaks were caused by the same strain of SRSV w as investigated by the polymerase chain reaction (PCR). New inosine-co ntaining PCR primers were designed to amplify the RNA polymerase regio n of SRSV cDNA from genetic groups I and II. The PCR using the group I I primers achieved a higher detection rate for SRSVs in faecal samples (68% of samples positive from both outbreaks) than immune EM. SRSVs w ere not detected using the group I primers or using conventional degen erate PCR primers. The nucleotide sequences of PCR amplicons from both outbreaks were identical providing molecular epidemiological evidence for the involvement of a single SRSV strain. Comparison of the RNA po lymerase region of this virus with the equivalent regions of genetic g roup I (69.4-75.0% amino acid identity) and genetic group II (88.9-100 % amino acid and 77.1-88.1% nucleotide identity) SRSVs revealed that t he causative SRSV was a distinct member of genetic group II. (C) 1995 Wiley-Liss, Inc.