Immunoassay Assessed for Diagnosis of Norovirus Gastroenteritis

The sensitivity and specificity of a commercial Norovirus immunochromatographic test has been evaluated on human stool samples.

The immunochromatographic test is based on reverse transcription-polymerase chain reaction (RT-PCR) and the sensitive RT-nested PCR and was compared with another commercial real-time RT-PCR for detection of Norovirus in stool samples.

Scientists at Mahidol University (Bangkok, Thailand) tested 86 stool samples for noroviruses using the commercial immunochromatographic test RIDA QUICK Norovirus, which uses the biotin-streptavidin-peroxidase method. In addition, 54 Norovirus-positive samples from a second test group were also detected, and the copy number of Norovirus quantified by using a commercial real-time RT-PCR. Norovirus GI and GII antigens in stool samples can be detected using the RIDA QUICK Norovirus Test.

The sensitivity was analyzed using stool samples of the two test groups, which were confirmed for Norovirus infection by RT-PCR and RT-nested PCR, respectively. Based on the RT-PCR, the sensitivity of the RIDAQUICK Norovirus assay (R-Biopharm; Darmstadt, Germany) was 83.3% (15/18 samples), but compared with the RT-nested PCR, the sensitivity decreased to 48.2% (26/54 samples). The specificity of the assay was analyzed using Norovirus-negative stool samples from the control group and accounted for 87.5% (28/32 samples). The assay revealed false positives of 12.5%.

Among 23 stool samples showing Norovirus positive by both the RIDA QUICK Norovirus assay and the real-time RT-PCR (Shanghai ZJ Bio-Tech, Shanghai, China), the virus could be detected in samples taken on days 1–8 after onset of illness and these samples harbored Norovirus GII. The real-time RT-PCR for the simultaneous detection of Norovirus GI and GII and quantitation was completed on the LightCycler 1.5 Instrument Real Time PCR System (Roche Diagnostics, Mannheim, Germany). Viral ribonucleic acid (RNA) was extracted using the QIAam Viral RNA extraction kit (QIAGEN GmbH, Hilden, Germany).

The authors concluded that the RIDA QUICK Norovirus assay is rapid and simple to perform. The assay has high sensitivity and specificity. This method is appropriate to use for early diagnosis of acute gastroenteritis caused by noroviruses and for rapid screening of Norovirus infections in patients with acute gastroenteritis in both developed and developing countries where the RT-PCR method has not been established for routine diagnosis. However, negative results where Norovirus is strongly suspected should be further tested by more sensitive molecular techniques.

The study was published online on February 23, 2012, in the European Journal of Clinical Microbiology & Infectious Diseases.

Related Links:
Mahidol University
R-Biopharm
Roche Diagnostics