Inaktivierung von Norovirus in Lebensmitteln: Inokulationsstudie mit humanem Norovirus

Contaminated foods play an important role in the transmission of human pathogenic Noroviruses. This study examines the influences of the physico-chemical processes on the inactivation and survival capability of human Norovirus (GGII) in selected foods. Artificially contaminated food was subjected to processes (e.g. heating, cooling, freezing), which are applied in food production technology for preservation and by consumers for preparation and storage. The inactivation rate was established by comparing the number of Norovirus in untreated and treated food samples (before and after the process). A method based on ultrafiltration was used to extract the virus from the food and this was validated via an internal process control (Phage MS2). The Norovirus was detected using real-time Reverse Transcriptase (RT)-PCR with a TaqMan probe. It was quantified with the aid of an external standard curve based on a recombinant RNA standard. In order to detect only intact virus particles, the free RNA in the samples was removed by adding RNase that was subsequently deactivated by adding RNase inhibitors. Significant titre reductions were ascertained above all as a result of heat treatments. Cooling, freezing, acidifying and moderate heat treatments (pasteurising) led to no or very slight Norovirus reduction. In addition to the results on the persistence of human Norovirus in various foods, comprehensive data on matrix-specific, protective effects, recovery rates and inhibitory influences on the real time RT-PCR were gathered within the context of the study.