The exploration of immunologic mechanisms has entered a new phase, that of molecular biology,1 resulting in an improved understanding of diseases that arise from immunologic injury. From among the many basic and clinical contributions, Science has selected a "Molecule of the Year," the DNA polymerase, which drives the polymerase chain reaction.2
The polymerase chain reaction has been used to detect proviral DNA in the peripheral blood mononuclear cells of persons infected with human immunodeficiency virus 1 who are seropositive and virus culture negative. An assay has also been developed to detect human immunodeficiency virus 1 RNA in patients with acquired immunodeficiency syndrome and acquired immunodeficiency syndrome—related complex, which raises the possibility of early detection of human immunodeficiency virus in plasma and serum through gene amplification,3 of obvious benefit in blood bank screening.
The long-term safety and efficacy of zidovudine therapy have been examined in 229 subjects with