[Evaluation of Norovirus Detection Method Based on a Newly Developed Bioluminescent Enzyme Immunoassay (BLEIA)...

Noroviruses (NoV) are a major cause of nonbacterial acute gastroenteritis. To efficiently control NoV infection, preventing the transmission of the virus from NoV-infected food-handlers to food may be crucial. At present, reverse-transcription real-time PCR (rRT-PCR) methods may be used as a sensitive method to detect NoV, but the method has the drawbacks of being expensive and time consuming. Other conventional immunological methods such as ELISA and immuno-chromatographic tests are more economical and easier to use than rRT-PCR, but these methods may not be highly sensitive. To overcome these problems, we have developed a novel bioluminescent enzyme immunoassay (BLEIA) system. The system is fully automated and this may enable the rapid, highly sensitive detection of NoV. To practically evaluate the BLEIA, we measured a number of fecal specimens from the patients with acute-gastroenteritis due to NoV infection or healthy adult volunteers in Japan. The performance of the BLEIA was compared with the Loop-Mediated Isothermal Amplification (LAMP) assay and rRT-PCR. The sensitivity, specificity, and correspondence rate of the BLEIA were 93.1% (135/145), 100% (87/87), and 95.7% (222/232), respectively, and those of the LAMP assay were 91.0% (132/145), 98.9% (86/87), and 94.0% (218/232), respectively. A good correlation (r = 0.72) was obtained between the virus loads measured using rRT-PCR and the cut-off index values of the BLEIA, and the sensitivity of the BLEIA was estimated to be 10(5)-10(6) copies/g stool samples. No cross-reactivity toward other closely related or enteric viruses was found. The results indicated that the BLEIA may be applicable for the conventional screening for NoV detection with a large number of fecal specimens from the patients and food-handlers.