Norovirus detection in shellfish using two Real-Time RT-PCR methods

Shellfish are recognized as a potential vehicle of viral diseases. The aim of the present study was to determine the ability of two real-time RT-PCR methods (an in-house method and a commercial kit) for detecting Norovirus (NoV) belonging to genogroups GI and GII in shellfish. The analyses were performed both on a Norovirus Reference Panel (NRP), consisting of synthetic RNA, and on naturally contaminated mussels. For the experiments carried out on the NRP a statistically significant difference (chi(2)=8.03) was shown between the results obtained by the two methods. The in-house real-time RT-PCR allowed the detection of all genotypes belonging to GI and GII, while the commercial kit was not suitable for the detection of the majority of the GI sequences constituting the panel. No significant difference was instead detected in the experiments carried out on shellfish, where the presence of GI was always concomitant with GII. Both methods were suitable for detection of NoV in shellfish, however the in-house real-time RT-PCR method had the advantage of differentiating GI and GII contamination. As regards the shellfish analysed, a considerable frequency of NoV contamination (34.4% of the samples) was detected, with a predominance of NoV GII.