Lymphadenopathy in macaques experimentally infected with the simian immunodeficiency virus (SIV).

A T-cell tropic lentivirus of macaques the simian immunodeficiency virus (SIV), has morphologic, growth, and antigenic properties that indicate that it is related to the human immunodeficiency virus (HIV), the etiologic agent of the acquired immune deficiency syndrome (AIDS) in humans. Six juvenile macaques developed persistent lymphadenopathy (greater than 3 months in duration) after inoculation with SIV. The histologic appearance of the lymph nodes was characterized by marked follicular hyperplasia with abundant proliferative B cells infiltrating into the paracortex. The number of T8-positive lymphocytes equaled or exceeded the number of T4-positive lymphocytes in the paracortex. These findings, in association with immunologic abnormalities and a previously observed fatal immunodeficiency syndrome in SIV-infected macaques, provide further evidence of the importance of SIV-induced disease in macaques as a model for the study of AIDS.