Efficient isolation of HIV from plasma during different stages of HIV infection

Attempts to isolate human immunodeficiency virus (HIV) from blood plasma using inoculation of pellets from ultracentrifuged samples into cultures of peripheral blood mononuclear cells (PBMC) resulted in a high overall recovery rate (75%) of the virus from 76 patients in various stages of HIV infection. The recovery rate was dependent on the stage of infection; in patients with acquired immunodeficiency syndrome (AIDS) it was 100%, in AIDS-related complex (ARC) 86%, in persistent generalized lymphadenopathy (PGL) 64%, and in asymptomatic patients 54%. The HIV isolation rates compared favorably with those obtained after cocultivation of patient and target PBMC (overall recovery rate 67%). HIV was isolated from plasma but not from PBMC in 8 cases, whereas the reverse was true in 3 of 71 simultaneously tested cases. Isolation from plasma was found to be superior to detection of serum p24 antigen for the demonstration of HIV (positivity rates 75% and 30%, respectively). The time to appearance of p24 antigen in cultures inoculated with HIV-containing plasma samples was inversely related to the presence of detectable p24 antigen in serum. There was a significantly shorter time to culture positivity of plasma samples from AIDS and ARC patients than from PGL and asymptomatic patients. These results suggested that there is a progressive increase in the concentrations of infectious HIV in plasma from the asymptomatic to the AIDS stage. HIV isolation from plasma samples is a reliable means of demonstrating HIV viremia and has obvious advantages over the more commonly used cocultivation procedures. The frequent occurrence of cell-free, infectious HIV in plasma suggests that the majority of HIV-infected patients have a relative lack of functional neutralizing antibodies against the virus, at least during the late stages of disease.