Study Objective: To study the natural history of human immunodeficiency virus type 1 (HIV-1) infection, we used an in-vitro amplification technique to detect HIV-1 nucleic acid sequences in sequential aliquots of peripheral blood mononuclear cells from homosexual men enrolled in the Multicenter AIDS Cohort Study.
Design and Patients: Blinded, longitudinal study of 24 homosexual men who were positive for HIV-1 antibodies at a recent follow-up visit.
Measurements and Main Results: Coded clinical samples were evaluated using two enzyme-linked immunosorbent assays (whole virus and gp120-gp41 fragment), Western blot, a p24 antigen capture assay, virus cocultivation, and in-vitro amplification of conserved regions from the HIV-1 gag and env open-reading frames. In 20 of the 24 men an HIV-1 enzymatically amplified product was detected before HIV-1 antibody seroconversion: at 42 months before seroconversion in two cases; at 36 months in one case; at 30 months in one case; at 24 months in four cases; at 18 months in eight cases; at 12 months in one case; and at 6 months in three cases (median, 18 months). In the four other men, detection of an HIV-1 enzymatically amplified product was concurrent with confirmation of antibody seroconversion by Western blot.
Conclusions: There is a long and variable interval between virus acquisition and a diagnostic serum antibody response, perhaps due to the prolonged, persistent infection characteristic of the lentiviruses (family Retroviridae).