|CHOI, CHANGSUN - Chung-Ang University|
Submitted to: Food and Environmental Virology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/20/2016
Publication Date: 6/15/2016
Citation: Choi, C., Kingsley, D.H. 2016. Temperature-dependent persistence of human norovirus within oysters (Crassotrea virginica). Food and Environmental Virology. 8:141-147.
Interpretive Summary: Norovirus contamination of raw shellfish due to sewage release events is a serious problem. Current National Shellfish Sanitation Program (NSSP) regulations state that shellfish harvest should be closed for 3 weeks after an episodic sewage release or flood event. However, the duration of norovirus persistence within shellfish was previously unknown, particularly when water temperatures are low. In this publication, we demonstrate that norovirus can be detected in shellfish for at least 6 weeks after contamination and we further demonstrate that temperature has a substantial influence on the duration of human norovirus persistence in oysters. These results have important implication for shellfish management regulatory authorities.
Technical Abstract: This study characterizes the persistence of human norovirus in Eastern oysters (Crassostrea virginica) held at different seawater temperatures. Oysters were contaminated with human norovirus GI.1 (Norwalk strain 8fIIa) by exposing them to virus contaminated water at 15 degrees C, and subsequently holding them at 7, 15, and 25 degrees C for up to 6 weeks. Viral RNA was extracted from oyster tissue and hemocytes and quantitated by realtime RT-PCR. Norovirus was detected in hemocytes and oysters held at 7 and 15 degrees C for 6 weeks and in hemocytes and oysters held at 25 degrees C for up to 2 and 4 weeks, respectively. Results confirm that NV is quite persistent within oysters and demonstrate that cooler water temperatures extend norovirus clearance times. This study advocates for substantial relay times for norovirus-contaminated shellfish and suggests that regulatory authorities should consider the effects of water temperature after a suspected episodic norovirus-contamination event.