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Norovirus (NoV) is known to cause acute gastroenteritis in children worldwide. Although reverse transcription-PCR (RT-PCR) method is considered to be the "gold standard" for diagnosis of this viral infection, it requires skillful personnel and well-equipped laboratory. In this study, a rapid and easily performable diagnostic kit was developed using immunochromatographic method with rabbit polyclonal antibodies raised against recombinant virus-like particles (rVLPs) of most prevalent genotypes, genogroup II genotypes 3 and 4. This kit was evaluated for reactivity to rVLPs and detection of natural viruses in stool samples collected from children with diarrhea in comparison to the results obtained by RT-PCR. In the prospective assessment, the kit showed agreement rate of 84.1%, sensitivity of 69.8% and specificity of 93.7%. Genotyping of the RT-PCR positive samples by sequence analysis revealed that some heterogeneous genotypes were also detected while some in homogeneous genotypes occasionally showed false negative records resulting in lower sensitivity. No cross-reactivity with other common viral pathogens was observed. Taken together with the result of the detection limit of viral load as small as approximately 10(6-7)copies/g of stool, the current immunochromatography test is justified for screening for NoV infection with simple laboratory support.

An immunochromatography (IC) assay for rapid detection of norovirus (NoV) was evaluated with fecal samples collected from children who suffered from acute gastroenteritis during the winter season of 2007-2008 in Japan. A total of 75 fecal specimens were tested for NoV by the newly developed IC kit and by a gold standard RT-PCR method. The sensitivity, specificity, and agreement of this IC kit were 75.4%, 100%, and 80%, respectively. In addition, phylogenetic analysis revealed that the majority of NoV circulating in Japan during 2007-2008 belonged to the new variant GII/4 2006b genetic cluster. It was demonstrated that the IC kit evaluated in this study could detect these new variant NoV strains, which emerged recently in Japan. Therefore, it is suggested that this NoV IC kit could be used as an alternative method for the screening of NoV in fecal specimens, especially during the season of acute gastroenteritis outbreak.