[Screening for viral genomes in blood transfusion].

Despite sustained improvement of donor selection and serologic screening assays, there still remains a small but significant transfusion risk for each of the major viral agents (hepatitis B virus [HBV], hepatitis C virus [HCV], human immunodeficiency virus [HIV] and human T-cell leukemia virus [HTLV]). The risk is due to the failure of the screening tests to detect all the infected blood donations and in particular those which are recently infected in the pre-seroconversion window phase of infection, and the asymptomatic immunosilent chronic carriers who never develop antibodies. Another source of risk relates to variant strains of known viruses that are not detected by the current assays. The last potential risk involves the failure to detect infected blood samples because of inaccurate performances of the test process. In order to reduce this residual risk, the French health authorities requested the progressive introduction of nucleic acid technology (NAT) in blood screening so as to be generalised to all blood centres in the course of year 2000. Multicentric studies are underway to identify the most suitable techniques for the French network.