Transfusion virology: progress and challenges.

Discoveries of new human viruses and new technologies for their detection have made, and will continue to make, major contributions to the safety of blood transfusion. This article discusses the practical issues involved in the implementation of additional serological screening tests for viruses such as human T-lymphotropic virus, and reviews current information on the prevalence and pathogenicity of more recently discovered viruses, such as hepatitis G virus (HGV) or GB virus-C (GBV-C) and human herpes virus 8, a potential aetiological agent of Kaposi's sarcoma. Progress in the technology behind nucleic acid amplification techniques, such as the polymerase chain reaction (PCR), makes direct detection of viruses such as human immunodeficiency virus and hepatitis C virus possible. The use of such methods for screening will allow the earlier detection of acutely-infected individuals and the elimination of transmission from 'window' period donations before seroconversion for antibody. Establishing a framework for PCR-based screening would also enable the testing for others such as hepatitis A virus, parvovirus B19 and GBV-C/HGV for which serological detection methods cannot be or have not been developed.