A comparison of polymerase chain reaction and an infectivity assay for human immunodeficiency virus type 1 titration during virus inactivation of blood components

Three examples of human plasma‐derived concentrates, intermediate‐ purity factors VIII and IX, and fibrinogen were spiked with tissue culture‐grown human immunodeficiency virus type 1 (HIV‐1) strain RF. All examples were freeze‐dried and heated at 80 degrees C for 72 hours by using validated production process models. HIV‐1 infectivity was measured by a syncytial infectivity assay in C8166 cells and then compared with levels determined by nested HIV polymerase chain reaction (PCR). The infectivity assay demonstrated a reduction index of at least 4.5 log10, while PCR showed an average 1.7 log10. Large amounts of HIV‐ 1 RNA (105) were still detectable by PCR in samples in which infectivity assays failed to detect any HIV‐1. These data suggest that HIV‐1 PCR levels do not parallel HIV‐1 infectivity levels during virus‐ inactivation procedures involved in coagulation factor concentrate production. PCR was able to detect the RNA associated with inactivated HIV‐1 particles in the factor concentrates, which allows the conclusion that PCR is not a useful test with which to monitor virus‐inactivation procedures such as heating at 80 degrees C for 72 hours. This judgment contrasts with the more definite and sensitive role of PCR in diagnosing HIV‐1 infection in patients in whom a positive HIV‐1 PCR result correlates with active HIV‐1 infection and with PCR's usefulness in monitoring virus removal.