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Title:   Author  item
                                            Kingsley, Daviditem
                                            HOOVER, DALLAS - UNIVERSITY OF DELAWAREitem
                                            PARAFRAGKOW, EFI - UNIVERSITY OF DELAWAREitem
                                            Richards, Gary
  Submitted to: Journal of Food Protection
                                    Publication Type: Peer Reviewed Journal
                                    Publication Acceptance Date: 4/25/2002
                                    Publication  Date: 10/1/2002
                                    Citation: N/AInterpretive Summary: The process of "pressure pasteurization" is a new commercial process applied to raw shellfish for the purposes of pathogenic bacterial inactivation.  In this publication, we explored the possibility of inactivating nonenveloped viruses, principally hepatitis A virus and Norwalk virus, for which raw shellfish consumption is a common  source of outbreaks.  We demonstrated that approximately 4500 atmospheres (atm) of pressure for 5 min completely inactivated high titer HAV stock with lesser degrees of inactivation observed between 4500 and 3000 atm.  Enhanced inactivation of HAV was observed when treatments were extended to 15 minutes.  However, when HAV was diluted in seawater, reduced sensitivity to pressure was observed.  Since Norwalk virus cannot be propagated in vitro and pressure treatment does not destroy the viral RNA, neither live  plaque assays or RT-PCR methods could be useful to evaluate Norwalk inactivation.  Therefore, a genetically-related virus, feline calicivirus, (FCV) as evaluated and shown to be inactivated at 3000 atm.  Poliovirus, a virus which is genetically related to HAV, was not inactivated at pressures as high as 6000 atm.  This work shows that "pressure pasteurization" can be a viable process for HAV-contaminated shellfish.  Whether similar pressures will be sufficient to inactivate Norwalk virus remains to be determined.
                                Technical Abstract: Potential application of high hydrostatic pressure processing (HPP) as a method for viral sterilization was evaluated.  A 7-log10 PFU/ml hepatitis A virus (HAV) stock, in tissue culture medium, was reduced to zero PFU after exposure to >450 megapascals (MPa) for 5 min.  Titers of HAV were reduced in a time- and  pressure-dependent manner between 300 and 450 MPa.  In contrast, poliovirus titer was unaffected by a five-min treatment at 600 MPa.  Dilution of HAV in seawater increased the pressure resistance of HAV, suggesting a protective effect of salts on virus inactivation. A series of RNase protection experiments indicated that viral capsids may remain intact during pressure treatment, suggesting that inactivation was due to subtle alterations of viral capsid proteins.  A 7-log10 PFU/ml stock of feline calicivirus, a Norwalk virus  surrogate, was completely inactivated after 5 min treatments with >275 MPa.  These data show that HAV and a Norwalk virus surrogate can be inactivated by HPP and suggest HPP will be capable of rendering potentially contaminated raw shellfish free of infectious virus.


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