Human Immunodeficiency Virus Type 1 Infection in Homosexual Men Who Remain Seronegative for Prolonged Periods

Abstract
Infection with the human immunodeficiency virus type 1 (HIV-1), as demonstrated by viral cultures, has been described in some patients before antibodies to HIV–1 can be detected, but the duration and frequency of such latent infections are uncertain. We selected prospectively a cohort of 133 seronegative homosexual men who continued to be involved in high-risk sexual activity, and we cultured 225 samples of their peripheral-blood lymphocytes, using mitogen stimulation to activate the integrated HIV-1 genome.