2004 Fiscal Year Final Research Report Summary
Study on the Elimination Method of Small Rounded Structure Virus (SRSV) from Oyster.
| Project/Area Number |
14360102
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
General fisheries
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| Research Institution | Hokkaido University |
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Principal Investigator |
YOSHIMIZU Mamoru Hokkaido University, Graduate School of Fisheries Sciences, Professor, 大学院・水産科学研究科, 教授 (40122915)
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| Co-Investigator(Kenkyū-buntansha) |
TAJIMA Kenichi Hokkaido University, Graduate School of Fisheries Sciences, Professor, 大学院・水産科学研究科, 教授 (80002252)
NISHIZAWA Toyohiko Hokkaido University, Graduate School of Fisheries Sciences, Associate Professor, 大学院・水産科学研究科, 助教授 (10222184)
SAWABE Tomoo Hokkaido University, Graduate School of Fisheries Sciences, Associate Professor, 大学院・水産科学研究科, 助教授 (30241376)
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| Project Period (FY) |
2002 – 2004
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| Keywords | Oyster / Norovirus / SRSV / Elimination / Electryzed seawater / UV irradiation / Shell remove / FCV |
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| Research Abstract |
Oysters (Crassestrea gigas) harvested from major cultivation areas are commonly contaminated with Escherichia coli. Also, some places, oyster concentrates small rounded structured virus (SRSV ; norovirus). It's very important to remove the E.coli, food born bacteria and norovirus. E.coli has to be removed from oysters during oyster purification by re-laying in a non-polluted seawater. Although sodium hypochlorite or UV irradiation is used to disinfect seawater, it's difficult to treat large volumes of seawater. Recently the bactericidal and virucidal effects of hypochlorite produced by electrolysis of seawater were examined against pathogenic bacteria and viruses.
SRSV (norovirus) is not able to replicate in the established cell line, and its difficult to determine the virus infectivity. This virus is belonging to family Caliciviridae, and cat pathogenic virus ; FCV that is able to replicate in cat cell line. In this study, virucidal effects of UV irradiation, hypochlorite and high pres
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sure on FCV infectivity were studied to eliminate the FCV from oyster. Stability of FCV in sea water and intestinal contents of oyster was also studied.
FCV was inactivated at the dose of 1.0x10^4 micro W・sec/cm^2, electrolyzed seawater chlorine concentration controlled at 0.20〜0.4mg/L, and 800MPa・40℃・5min FCV infectivity decreased rapidly in sea water at the temperature 20℃ or high. In the intestinal contents of oyster, FCV was inactivated by antiviral substances produced by intestinal bacteria. These results indicate that combination of 3 conditions ; (1)using a electrolyzed sea water containing the 0.3 mg/L hypochlorite, (2)harvest in sea water at the temperature 20℃ or high, (3)remove the shell using a 800 MPa・at 40℃ for 5 min. Seawater electrolyzers have ability to treat large volumes of water and cost performance of this method is better than that of UV irradiation. From these results, it is considered that electrolysis of seawater could be a useful method for post harvest elimination of norovirus from oysters. Less
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