金コロイドを用いた新規イムノクロマト法による便中ノロウイルス検出試薬の有用性

Abstract

We evaluated the usefulness of ImmunoCatch-Noro (Eiken Chemical Co., Ltd.) (IC-A), a newly developed immunochromatography kit using Au colloid, for the detection of norovirus in stool specimens collected from patients with acute gastroenteritis during the three-year period from 2008-2011. When a total of 316 specimens were tested by RT-PCR and direct sequencing of the PCR products, norovirus was detected in 198 specimens (62.7%), including nine genotypes (GI/2, GI/4, GI/8, GII/1, GII/2, GII/3, GII/4, GII/6 and GII/ 13). The most frequently isolated genotypes were GII/3 (64), GII/2 (59) and GII/4 (58), accounting for about 90% of the positive specimens. As compared to RT-PCR, the sensitivity, specificity and concordance rate of IC-A were 87.4% (173/198), 100% (118/118) and 92.1% (291/316), respectively. Twenty-five positive specimens that were positive by RT-PCR were negative by IC-A, however there were no false-positive results of IC-A. On the other hand, the commercially available immunochromatography kit (IC-B), which was tested for comparison, had a sensitivity, specificity and concordance rate of 59.6% (118/198), 96.6% (114/118) and 73.4% (232/316), respectively, containing 80 false-negative and four false-positive specimens. All of the 118 specimens positive by both IC-B and RT-PCR were also interpreted as positive by IC-A. The detection rates of the predominant genotypes (GII/2, GII/3 and GII/4) by IC-A were 88.1%, 87.5% and 89.7%, respectively. In contrast, those by IC-B were only 32.2%, 67.2% and 81.0%, respectively. These results show that IC-A had adequate sensitivity and cross-reactivity for a wide range of GI and GII genotypes, and also had high specificity. In conclusion, IC-A is a useful rapid-diagnostic kit for the detection of norovirus, however, its current application is limited for stool specimens.