Evaluation of various methods for recovering human norovirus and murine norovirus from vegetables and ham

We evaluated and optimized each step in an analytical method for detecting norovirus from various foods. We characterized the buffers needed for eluting norovirus from foods such as ham and lettuce. Two different concentration methods, polyethylene glycol (PEG) precipitation and hollow fiber ultrafiltration (HUF), were compared using both murine norovirus (MNV) and human norovirus (HuNoV). For PEG precipitation, an elution buffer containing 3% beef extract (pH 7.1) was more suitable than 0.05 M glycine plus 0.14 M NaCl (pH 7.5), and the recovery efficiency increased with increasing molecular weight of PEG. To determine the optimal buffer for concentrating norovirus by HUF, glycine buffers with different pH values and ionic strengths were examined as elution buffers. Overall, HUF was more efficient for norovirus recovery than was PEG precipitation. Because there was a significant positive correlation between MNV and HuNoV results, MNV could be a useful surrogate for detecting HuNoV in foods.