Molecular Assay Detects Norovirus in Fecal Specimens

A new real-time reverse transcription polymerase chain reaction (RT-PCR) assay has been evaluated in for the detection of human Norovirus in stool specimens.

Noroviruses are a genetically diverse group of single-stranded ribonucleic acid (RNA), nonenveloped viruses in the Caliciviridae family and are classified into five genogroups by phylogenetic analysis of the capsid protein, of which genogroups II (GII), I (GI), and IV (GIV) are responsible for human outbreak.

Scientists at the Hallym University College of Medicine (Seoul, South Korea) analyzed 281 fecal suspensions (10% to 20% fecal specimen diluted with saline) collected and stored at -70 °C between August 2010 and April 2011. These comprised 109 Norovirus-positive and 172 Norovirus-negative stool samples, as determined using a Norovirus enzyme-linked immunosorbent assay (ELISA).

RNA was extracted from fecal suspensions and prepared using the QIAamp Viral RNA Mini Kit (Qiagen; Hilden, Germany) and the Qiagen QIAcube platform. The AccuPower Norovirus Real-time RT-PCR assay (Bioneer Corporation; Daejeon, South Korea) and the RIDAGENE Norovirus V assay (R-Biopharm, Darmstadt, Germany) were compared as Norovirus assays. Norovirus positivity and genotype were confirmed by direct sequencing.

Of the 109 Norovirus-positive samples by ELISA, 91 (83.5%) were positive by both PCR kits, and two (1.8%) were positive only by the AccuPower kit, whereas 16 cases (14.7%) were negative by both PCR kits. Of the 172 Norovirus-negative samples by ELISA, 159 (92.4%) were negative, and five (2.9%) were positive by both PCR kits, one (0.6%) was positive by the RIDAGENE kit, and seven (4.1%) were positive by the AccuPower kit. The lowest mean numbers of genome copies of GI and GII that could be detected by the AccuPower assay were 12.3 and 5.6 RNA copies/reaction, respectively.

The authors concluded that the AccuPower Norovirus Real-time RT-PCR Kit showed good analytical and clinical performance, including excellent analytical sensitivity and reproducibility, without cross-reactivity and they recommend this assay system as an efficient diagnostic tool for Norovirus infection. Noroviruses are responsible for an estimated 218,000 deaths each year among children younger than five years in developing countries and 1.1 million hospitalizations worldwide. The study was published in the January 2014 edition of the journal Diagnostic Microbiology and Infectious Disease.

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Hallym University College of Medicine
Qiagen
Bioneer Corporation