Effective inactivation of a wide range of viruses by pasteurization

Gröner, Albrecht; Broumis, Connie; Fang, Randel; Nowak, Thomas; Popp, Birgit; Schäfer, Wolfram; Roth, Nathan J.

CONCLUSION: Pasteurization is a very robust and reliable virus inactivation method with a broad effectiveness against known blood-borne pathogens and emerging or potentially emerging viruses. Pasteurization has proven itself to be a highly effective step, in combination with other complementary safety measures, toward assuring the virus safety of final product. S tudies on inactivation of viruses in biologics were initially triggered after 23,000 cases of hepatitis were reported in US Armed Forces personnel in 1942 associated with the administration of certain lots of yellow fever vaccine, stabilized with non-heattreated human serum. 1 Subsequently, the effectiveness of From 1 Global Pathogen Safety, CSL Behring GmbH, Marburg, pasteurization as a virus inactivation technique was clinically demonstrated in human volunteers who received either a pasteurized or non-heat-treated dose of human serum albumin (HSA) spiked with plasma containing infectious hepatitis B virus (HBV). Subjects who received the pasteurized HBV-spiked HSA displayed no clinical signs of infection, as monitored by liver function assays, in contrast to the subjects who received the non-heattreated HBV-spiked HSA. 2 As plasma fractionation techniques improved, coagulation factors, immunoglobulins, and enzyme inhibitor concentrates were isolated at industrial scale from large volumes of pooled plasma. Although these therapeutic products provided life-saving and lifesustaining therapeutic options for patients, they also intermittently transmitted blood-borne viruses, 3,4 especially HBV, hepatitis C virus (HCV), and human immunodeficiency virus (HIV). Therefore, methods that had a high capacity to inactivate and/or remove viruses were integrated in the industrial manufacturing process of plasmaderived products. The first reliable virus inactivation method, pasteurization (heat treatment in aqueous solution at 608C for 10 hr), to effectively inactivate HBV and HCV (at that time called non-A/non-B hepatitis virus) in coagulation factor concentrates was studied and implemented at Behringwerke (a predecessor company of CSL Behring) in the late 1970s and early 1980s by employing suitable stabilizers and conditions to permit pasteurization without modifying the product, for example, formation of neoantigens or activated factors. As no cell culture assay system for HBV and non-A/non-B hepatitis virus was available, the capacity of the pasteurization step to inactivate these hepatitis viruses was assessed in chimpanzees 5 or in ducklings. 6 After HIV was known to be transmitted by blood transfusion and some plasma-derived products, studies were performed using cell culture systems to document the heat sensitivity of HIV. 7 Hemovigilance studies demonstrated the effectiveness of the pasteurization step introduced in the manufacturing process of a Factor (F)VIII/von Willebrand factor (FVIII/ VWF) concentrate to prevent the transmission of HBV, HCV (non-A/non-B hepatitis virus), 8 and HIV 9 at the time when HCV was not a known characterized virus 10 and when no donor screening assays were available for HIV. 11, 12 Virus validation guidelines were ultimately developed and issued by the European authorities, requiring manufacturers to carry out studies to demonstrate the capacity, reliability, and effectiveness of the manufacturing processes to inactivate and/or remove viruses potentially present in the starting material (plasma pool for fractionation). [13] [14] [15] These guidelines r