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Norovirus, clams, depuration, tissue culture, RT-PCR


Human Norovirus has been reported as the major non-bacterial cause of human gastroenteritis due to the consumption of contaminated bivalve mollusks. The European legislation established microbiological criteria only for bacteria (Salmonella spp.  and Escherichia coli),  while no viruses have still been considered. In this study,  samples of Chamelea gallina were harvested along the Central  Adriatic coasts (Italy) and artificially contaminated with  Murine  norovirus-1 (MNV-1) up to a  final concentration of 103TCID50/ml  in water.  They were subject to a  depuration process in a  closed-circuit system using both ozone and ultraviolet light. Four experimental trials (100 specimens/trial) were performed and, at the end of depuration, the digestive glands of mollusks were examined by means of two methods –namely, RT-PCR and tissue culture. The results of RT-PCR ranged from 103.17 to 104.60 TCID50/ml, and the constant presence of MNV-1 was confirmed by the tissue culture as well. In conclusion,  no significant viral reduction was obtained, but the contaminated bivalve mollusks remained infectious until the end of the depuration treatment. The proper cooking of live bivalve mollusks could be considered the most important preventive measure against this sanitary risk.

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