Inactivation of AIDS-causing retroviruses by the manufacturing procedures for human plasma proteins

Human retroviruses causing AIDS (HIV) may occur in human plasma. Since HIV contaminated plasma cannot be completely excluded by testing for anti-HIV, AIDS safety of human plasma products can only be achieved by introducing HIV inactivating and/or eliminating methods into the manufacturing procedure. Here we review a number of methods used when manufacturing plasma derivatives at Behringwerke. These methods were previously developed either to produce a protein of required purity or to manufacture hepatitis safe products. Methods used to produce purer proteins are ethanol fractionation, pepsin treatment, affinity chromatography or various protein precipitation procedures. The method developed at Behringwerke for inactivating infectious viruses in plasma protein preparations not destroying the biological activities of the human protein is pasteurization, i.e. 10 h heat treatment of the aqueous protein solution at 60 degrees C. To investigate the HIV inactivating efficiency of the methods mentioned above, aliquots of an infectious HIV type 1 concentrate were added to a protein preparation, the resulting HIV spiked preparation treated according to the method to be studied and the amount of infectious HIV in this preparation determined before and after treatment. By all methods reported on here the HIV type 1 isolate was completely inactivated resulting in high inactivation factors. In addition, the heat stability of HIV type 2 was tested in aqueous solution at 60 degrees C proving that both HIV-1 and HIV-2 isolates are of comparably low heat stability under these conditions. From the results discussed here it can be concluded that all commercial human protein products of Behringwerke derived from either human plasma or placenta do not contain any infectious retrovirus causing AIDS and thus have a high margin of safety regarding the transmission of AIDS.