Different Methods Compared for Norovirus Detection

Commercial molecular and immunological tests have been evaluated in their ability to detect noroviruses in stool samples.

Two polymerase chain reaction (PCR) assays and an enzyme-linked immunosorbent assay (ELISA) have been tested under clinical conditions to diagnose and distinguish genogroups of noroviral infections.

Clinical microbiologists at the University of Szeged (Hungary) examined 61 stool samples for noroviruses from patients with clinical symptoms of acute gastroenteritis: nausea, vomiting, and/or three or more loose stools in 24 hours. For Norovirus detection two PCR assays, The Argene Calici/Astrovirus Consensus kit and the Norovirus Primer and Probe Set RT-PCR, were used in combination with the IDEIA ELISA method. The latter kit is an enzyme immunoassay for the qualitative determination of noroviruses of genogroups I (GGI) and GGII in stool samples. The IDEIA Norovirus ELISA system (DakoCytomation; Ely, UK) utilizes wells coated with GGI- and GGII-specific monoclonal antibodies. It is a very simple, rapid, but labor-intensive method for simultaneous screening of a large number of samples.

The ELISA method takes approximately two hours to carry out. The Argene kit takes 36 hours to achieve a result, while the Norovirus Primer and Probe Set real time-PCR method takes about six hours. All three methods were 100% specific for noroviruses. The sensitivity of the three methods was as follows: IDEIA ELISA was 78.9%; the Argene kit (Argene; North Massapequa, NY, USA) was 92.8%; and the Norovirus Primer and Probe Set (Cepheid; Sunnyvale, CA, USA) was 91.2%. The PCR and ELISA systems detected 52 Norovirus-positive samples, only one of which belonged to genogroup I and all the others to genogroup II. Although the ELISA kit had a lower sensitivity compared to the PCR ones, it may be useful for large-scale testing. However, the authors suggested that ELISA-negative outbreaks should be retested by RT-PCR methods.

As noroviruses are uncultivable, in clinical practice, it is important to obtain results as soon as possible in order to minimize the spread of the virus within and between hospital units. The results of this study suggest that noroviruses, and predominantly genogroup II of the norovirus genera, play an important role in outbreaks and sporadic cases of acute gastroenteritis, not only in infants and young children, but also in adults. The study was published in August 2011, in the journal Diagnostic Microbiology and Infectious Disease.

Related Links:
University of Szeged
DakoCytomation
Cepheid