Background: Despite the fact that human immunodeficiency virus (HIV) is transmitted by sexual contact, the biology of this mode of transmission remains largely undefined. HIV is present in semen in both cell-free and cell-associated forms and can be isolated from asymptomatic individuals and AIDS patients. The source of HIV in semen and the target cells for HIV transmission to men are unknown. Epidemiologic studies have shown that in men, the presence of an intact foreskin is associated with increased risk of HIV infection.
Experimental design: The reproductive tracts from 13 chronically simian immunodeficiency virus (SIV)-infected adult male rhesus macaques were examined for this study. Routine histologic examination was undertaken to characterize the reproductive tract pathology. In situ hybridization and immunohistochemistry were used to localize SIV-infected cells and determine the immunophenotype of inflammatory infiltrates.
Results: SIV-infected cells (macrophages, T cells) were found at all levels of the reproductive tract and were commonly associated with inflammatory lesions. Infected cells were found most consistently in the epididymis. In one animal, SIV-infected cells (presumably Langerhans cells) were present in the stratified squamous epithelium of the foreskin. Testicular atrophy and degeneration were relatively common findings. The most common lesion in the accessory glands was mild lymphocytic inflammation. In addition, atrophy of the glandular elements and interstitial fibrosis in the prostate gland were found. One animal had a granulomatous epididymitis with multinucleate giant cells that may have been a primary SIV lesion.
Conclusions: The reproductive tract pathology in chronically SIV-infected male rhesus macaques and AIDS patients is similar. SIV-infected cells can be found at all levels of the male rhesus macaque reproductive tract and SIV can infect cells in the mucosal epithelium of the foreskin. This latter finding indicates that target cells for HIV transmission may be present in the foreskin epithelium of uncircumcised men.