Effect of viral nucleic acid testing on contamination frequency of manufacturing plasma pools

In Europe, all plasma pools used for manufacturing of plasma derivatives must be tested negative for hepatitis C virus (HCV) RNA by nucleic acid amplification techniques (NAT) with a defined minimal sensitivity. For a subset of pools, quantitative B19V DNA NAT is also mandatory. NAT for further viral targets was introduced by most of the manufacturers on a voluntary basis. The contamination frequency of plasma pools with HCV RNA, human immunodeficiency virus (HIV)-1 RNA, and hepatitis B virus (HBV) DNA was investigated with representative pools before and after introduction of NAT.

A total of 873 pools from 1996 and 331 pools from 2006 were analyzed for the detection of HCV RNA, HIV RNA, and HBV DNA with an automated multiplex NAT system. The pools were obtained from different manufacturers and the source material was of European and US origin.

HCV RNA, HIV-1 RNA, and HBV DNA were detectable in plasma pools from 1996 with the following frequencies: 17.8 percent (HCV RNA), 0.8 percent (HIV-1 RNA), and 0.5 percent (HBV DNA). Viral genome concentrations were up to 3 x 10(4) IU HCV RNA per mL and 7 x 10(3) IU HIV RNA per mL, whereas HBV DNA was below the quantitation limit of the quantitative NAT assay. Among the pools from 2006, one pool (0.3%) was found HCV RNA-positive at low titer (<10 IU/mL), whereas no HIV RNA or HBV DNA was detectable in any pool.

The results imply that the introduction of NAT systems for the detection of viral genomes has largely reduced the contamination frequency and viral loads of manufacturing plasma pools and thereby improved the safety margin for human medicinal products manufactured from human plasma. Even with NAT, however, low-titer contamination may occur, which will be coped with by virus inactivation steps included into the manufacturing of plasma derivatives.