91E-10 |
Treatment of hepatitis A virus and feline calicivirus with high hydrostatic pressure |
D. H. Kingsley1, E. PAPAFRAGKOU2, D. G. Hoover2, and G. P. Richards3. (1) U.S. Department of Agriculture, Agricultural Research Service, Delaware State University, W.W. Baker Center, Dover, DE 19901, (2) Department of Animal & Food Sciences, University of Delaware, Newark, DE 19717, (3) Department of Agriculture, Agricultural Research Service, Delaware State University, W.W. Baker Center, Dover, DE 19901 It is estimated that human enteric viruses cause the greatest incidence of foodborne illness in the U.S. The two greatest viral threats to consumers of raw shellfish are hepatitis A and Norwalk viruses, which concentrate within the shellfish tissue after exposure to virus-contaminated water. Depuration or other purging techniques are ineffective as a means of shellfish purification. Our objective was to evaluate high hydrostatic pressure processing (HPP) for inactivation of hepatitis A virus (HAV) and feline calicivirus (FCV), a Norwalk virus surrogate capable of propagation in cell culture. Approximately 1 mL of undiluted virus stock (HAV and FCV) was heat-sealed in sterile plastic tubing and pressurized at ambient temperature for 5 or 15 min from 0 to 500 MPa. To mimic the environmental context of shellfish, viral stocks were also diluted in seawater (final concn=27.4 ppt) prior to HPP treatment. Exposures of 5 min at 450 MPa were sufficient to completely inactivate 7-log/mL titers of HAV in isotonic Dulbecco's Modified Eagle Medium (DMEM) supplemented with 10% fetal calf sera. Five-min treatments at <300 MPa did not reduce HAV infectivity, while exposures between 300 and 450 MPa generated linear inactivation curves. Fifteen-min treatments showed a greater degree of inactivation relative to 5-min treatments; however, dilution of viral stock in seawater resulted in similar levels of inactivation using 5-min exposures. For FCV, 5-min treatments at 275 MPa were sufficient to completely inactivate 7-log/mL titers. HPP has promise for the inactivation of virus-contaminated foods. Although it appears that higher pressures are required to inactivate HAV than has been shown for Vibrio parahaemolyticus, HPP may be especially appealing for viral sterilization of raw shellfish, provided they are acceptable to consumers. Our preliminary findings suggest HAV was inactivated by HPP within oyster extracts to a similar extent as in DMEM. Whether HPP will inactivate non-culturable Norwalk-like caliciviruses remains to be determined; however, the inactivation of FCV at 275 MPa suggested optimism.
Session 91E, Nonthermal Processing: Nonthermal processing of foods
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