Effect of High Pressure Processing on a Wide Variety of Human Noroviruses Naturally Present in Aqua-Cultured Japanese Oysters.

The contamination of oysters with human norovirus (HuNoV) poses a human health risk, as oysters are often consumed raw. In this study, the effect of high pressure processing (HPP) on a wide variety of HuNoVs naturally present in aqua-cultured Japanese oysters was determined through a polymerase chain reaction-based method with enzymatic pretreatment, to distinguish between infectious HuNoV. Among five batches, genogroup I.

Effect of High-Pressure Processing on Human Noroviruses in Laboratory-Contaminated Oysters by Bio-Accumulation.

The contamination of oysters with human noroviruses poses a human health risk, since oysters are often consumed raw. In this study, human norovirus genogroup II was allowed to bio-accumulate in oysters, and then the effect of high-pressure processing (HPP) on human noroviruses in oysters was determined through a polymerase chain reaction (PCR)-based method with enzymatic pretreatment to distinguish infectious noroviruses. As a result, oysters could be artificially contaminated to a detectable level of norovirus genome by the reverse transcription-PCR.

Disinfection of fertilized eggs of the edible ascidian Halocynthia roretzi for prevention of soft tunic syndrome.

Azumiobodo hoyamushi, the causative agent of soft tunic syndrome, was likely introduced to farming sites of the edible ascidian Halocynthia roretzi via ascidian spat. The source of infection is thought to be cysts of A. hoyamushi that reside in the substrates on which the ascidian spat are attached, but not the spat themselves.

Soft tunic syndrome in the edible ascidian Halocynthia roretzi is caused by a kinetoplastid protist.

An etiological study was conducted to clarify whether the flagellate-like cells found in histological preparations of the tunic of diseased Halocynthia roretzi (Drasche) were the causative agent of soft tunic syndrome in this ascidian. When pieces of softened diseased tunic were incubated overnight in sterile seawater, live flagellated cells, which were actively swimming in the seawater, were observed in 47 out of 61 diseased ascidians (77%), but not in moribund or abnormal individuals with normal tunics (n = 36) nor in healthy animals (n = 19). The flagellate was morphologically very similar to those observed in histological sections of the diseased tunic.

Persistence of caliciviruses in artificially contaminated oysters during depuration.

The fate of calicivirus in oysters in a 10-day depuration was assessed. The norovirus gene was persistently detected from artificially contaminated oysters during the depuration, whereas feline calicivirus in oysters was promptly eliminated. The prolonged observation of norovirus in oysters implies the existence of a selective retention mechanism for norovirus within oysters.