Evaluation of the Loopamp® (loop-mediated isothermal amplification) kit for detecting Norovirus RNA in faecal samples

BackgroundNoroviruses (NoVs) are associated with outbreaks of diarrhoeal illness in hospitals, nursing and residential homes and other institutional settings. NoV strains exhibit wide genetic diversity, and different virus genogroups and genotypes co-circulate in any geographical region at the same time, although most outbreaks of gastroenteritis are predominantly associated with genogroup II. The reverse transcription-polymerase chain reaction (RT-PCR) is the gold standard for detecting NoVs in clinical samples.ObjectivesThis study evaluates commercialised Loopamp® kits for detecting NoV GI and NoV GII in faecal samples collected from patients with gastroenteritis and compares the results with those obtained using real-time RT-PCR with NoV genogroup sequence-specific detection.Study designFive hundred and ten faecal samples collected from patients with gastroenteritis were evaluated for the presence of NoV using the gold-standard real-time RT-PCRs and the Loopamp® assays.ResultsThe Loopamp® Norovirus GI and GII detection kits performed well compared to genogroup-specific real-time RT-PCR. Although the sensitivity of detection of GI strains (83.3%) was less than that for GII strains (97.4%), this will have little impact on the laboratory diagnosis of NoV, since GII strains are associated with the majority of outbreaks examined.ConclusionsThe Loopamp® GII detection kit is a sensitive method for detecting all the commonly circulating GII-4 strains included in the evaluation panel.