Safety of Human Blood Products: Inactivation of Retroviruses by Heat Treatment at 60 C

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Abstract
Acquired immune deficiency syndrome (AIDS) can be transferred to patients by blood transfusions or human blood preparations, such as cryoprecipitates or factor VIII concentrates. Retroviruses are discussed as infectious AIDS agents and more recently human T-lymphotropic retroviruses designated as HTLV type III and LAV (lymphadenopathy-associated virus) were isolated from AIDS patients. Whether heat treatment at 60.degree. C (pasteurization) of liquid human plasma protein preparations inactivates retroviruses was therefore investigated. Pasteurization had already been included in the routine manufacturing process of human plasma protein preparations in order to guarantee safety with regard to hepatitis B. Since high titer preparations of human retroviruses were not available, heat inactivation was studied using Rous sarcoma virus added to the various plasma protein preparations tested. This retrovirus which was obtained in preparations of 6.0 log10 FFU [focus-forming unit]/ml was shown to be at least as heat stable as 2 mammalian retroviuses studied, i.e., feline and simian sarcoma virus. In all of 8 different plasma protein preparations tested, Rous sarcoma virus was completely inactivated after a heat treatment lasting no longer than 4 h. Pasteurization of liquid plasma protein preparations at 60.degree. C over a period of 10 h must confer safety to these products with respect to AIDS, provided that the AIDS agents are retroviruses of comparable heat stability as Rous sarcoma virus and the mammalian retroviruses tested.