Effect of terminal (dry) heat treatment on non-enveloped viruses in coagulation factor concentrates

Terminal dry heat treatment effectively inactivated hepatitis A virus (HAV) and canine parvovirus added to high-purity factor VIII. After 24 h at 80 degrees C, HAV infectivity was reduced by > or = 4.3 log10 TCID50, as measured in a newly developed infectivity assay. The same reduction in virus titer was achieved after 2 h and before 6 h at 90 degrees C. Inactivation of hepatitis A virus was also seen in the freeze-drying step prior to heat treatment with an approximately 2.0 log10 reduction in titer. Similar results were obtained with a high-purity factor IX concentrate. Canine parvovirus was also inactivated at both temperatures, with residual infectivity being undetected after 48 h at 80 degrees C or 10 h at 90 degrees C. Canine parvovirus was not affected by lyophilisation. Canine parvovirus measurements by PCR did not reflect the levels of infectivity measured by the tissue-culture-based method. The addition of the terminal dry heat treatment to solvent/detergent could effectively eliminate the potential contamination of solvent/detergent-treated coagulation factor concentrates by non-lipid-enveloped viruses. However, careful evaluation for any increased induction of non-antigens for factor VIII, as a consequence of such treatment, is needed before use in patients can be recommended.