Development of enhanced primer sets for detection of norovirus.

Norovirus (NV) is a major viral pathogen that causes nonbacterial acute gastroenteritis and outbreaks of food-borne disease. The genotype of NV most frequently responsible for NV outbreaks is GII.4, which accounts for 60-80% of cases. Moreover, original and new NV variant types have been continuously emerging, and their emergence is related to the recent global increase in NV infection. In this study, we developed advanced primer sets (NKI-F/R/F2, NKII-F/R/R2) for the detection of NV, including the variant types. The new primer sets were compared with conventional primer sets (GI-F1/R1/F2, SRI-1/2/3, GII-F1/R1/F2, and SRII-1/2/3) to evaluate their efficiency when using clinical and environmental samples. Using reverse transcription polymerase chain reaction (RT-PCR) and seminested PCR, NV GI and GII were detected in 91.7% (NKI-F/R/F2), 89.3% (NKII-F/R/R2), 54.2% (GI-F1/R1/F2), 52.5% (GII-F1/R1/F2), 25.0% (SRI-1/2/3), and 32.2% (SRII-1/2/3) of clinical and environmental specimens. Therefore, our primer sets perform better than conventional primer sets in the detection of emerged types of NV and could be used in the future for epidemiological diagnosis of infection with the virus.