STUDY OF VIRAL PURIFICATION OF OYSTERS

Oysters (Crassostrea gigas) were experimentally contaminated by immersion in seawater containing rotaviruses SA11 for one hour. The rotaviruses SA11 had previously been adsorbed over algae (Dunaliella primolecta). Oyster depuration was then studied. The depuration was performed by immersion in closed loop circuit and in semi open circuit. In the semi open circuit, the seawater is replaced every 24 hours. It was shown that the rotaviruses, whether free or fixed on algae, were inactivated very rapidly when the seawater was continuously treated with U.V. (intensity ranging from 46.5 to 94 mW.s/cm2). The decontamination of the oysters in closed loop circuit starts at the first hours of immersion. For large viral contaminations, the decontamination was complete in 78 % of the cases after 72 hours. In the remaining 23 % of the cases, the contamination decrease varied from 82 % to 99.7 %. For lower viral contaminations, less than 30 viruses per gram of oyster tissue, the depuration was complete in 100 % of the cases after 72 hours. For large viral contaminations, the decontamination in semi open circuit was complete in only 82 % of the cases after 72 hours. For contaminations lower than 30 viruses per gram of oyster tissue, the depuration was complete in 100 % of the cases after 72 hours.