[Detection of human immunodeficiency virus in seronegative adults]

The diagnosis of human immunodeficiency virus infection is sometimes difficult or nonspecific, both in early and late stages, as the patients may be seronegative at the time of testing. Although serologic testing usually suffices to identify infected individuals and to follow up the course of the infection, in some cases direct detection of the virus is required. The culture of the mononuclear cells of the patient permits, after stimulation with mitogens and interleukin-2, the expression of viral antigens even in asymptomatic patients with latent or apparently nonproductive infection. In this way we have recovered the virus in four patients without serological evidence of infection. The possibility that human immunodeficiency virus infection can be undetectable with the usual diagnostic techniques, at least in a small proportion of patients, supports the need to use other methods such as direct viral culture to permit the identification of a greater number of infected individuals and the adoption of the appropriate prophylactic or therapeutic measures.