Abstract: Objective: To establish and compare two detection methods for human norovirus (HuNoV) in fruit (grape) and vegetable (green onion) samples using porcine gastric mucin-conjugated magnetic beads (PGM-MB) and polyethylene glycol 8000 (PEG8000), respectively. Methods: 1 RTU was defined from a consistently (triplicate) positive qRT-PCR signal of viral RNA extract with 4 × 10-6 dilution. A standard curve (1 to 10000 RTU) was established to convert Ct values to corresponding RTUs with an equation of y (Ct) = －3.6967 lg (RTU) ＋39.12 with R2 of 0.999. Green onion and grape samples were inoculated with various amounts of HuNoV, eluted and concentrated using PGM-MB or PEG8000 method. Viral RNA was extracted and quantified by qRT-PCR. Student,s t-test was used for statistical analysis. Results: The virus recovery rate by PGM-MB method ((31.61 ± 15.04)%) was significantly higher than that obtained by PEG precipitation method ((6.09 ± 1.56)%) at all doses of HuNoV inoculated onto grapes (P ＜0.001). For virus-inoculated green onions, the virus recovery rates from higher inoculation doses (625 RTU and 125 RTU) were comparable between both methods. However, the virus recovery rate by PGM-MB method from a lower dose of HuNoV (25 RTU) inoculated onto green onion samples was significant higher ((4.49± 0.79)%) than that from PEG precipitation method ((1.93 ± 0.18)%). In addition, PGM-MB method showed a lower detection limit than PEG precipitation method. Conclusion: PGM-MB method requires less time than PEG precipitation method, produces higher yield of HuNoV from various food samples, and hence exhibits higher sensitivity.

Key words: norovirus, porcine gastric mucin-conjugated magnetic beads, polyethylene glycol 8000, real-time polymerase chain reaction (RT-PCR)