INACTIVATION OF HEPATITIS-A VIRUS IN PLASMA PRODUCTS BY VAPOR HEATING

BACKGROUND: The transmission of hepatitis A virus (HAV) has been assoc iated with the use of a number of solvent/detergent-treated factor VII I concentrates and possibly a factor IX concentrate. These reports hav e emphasized the necessity of using virus-inactivation methods for pla sma products that are capable of inactivating nonenveloped viruses suc h as HAV. STUDY DESIGN AND METHODS: A simple, highly accurate titratio n procedure for HAV, which allows extensive kinetic investigations of virus-inactivation procedures, has been developed. This system has now been used to evaluate the efficacy of vapor heating in inactivating H AV after the addition of the virus to a range of human plasma products . RESULTS: It was demonstrated that HAV was significantly more thermos table than other picornaviruses, which reinforced the fact that such v iruses cannot be used as model viruses for HAV-inactivation studies. A one-step vapor-heating procedure was demonstrated to inactivate betwe en 5.9 and >6.3 log(10) of HAV in different products. A two-step vapor -heating procedure had the capacity to inactivate between >8.7 and >10 .4 log(10) of HAV. Both procedures were more effective in inactivating HAV than was the pasteurization procedure used for virus inactivation in human albumin solutions. CONCLUSION: These data demonstrate the ef ficacy of vapor heating in inactivating high-titer HAV after the spiki ng of plasma products with virus. This study confirms and explains the results of controlled clinical trials and long-term clinical usage wi th respect to the lack of HAV transmission by such vapor-heated produc ts.