ABSTRACT
Acquired immune deficiency syndrome (AIDS) is caused by a lymphotropic retrovirus, now known as the human immunodeficiency virus (HIV). The virus is acquired either by sexual intercourse (homosexual or heterosexual) or from the accidental introduction of material contaminated by the HIV into the systemic circulation. It was most common in homosexuals, drug addicts and the recipients of contaminated blood in the form of transfusions or concentrates, but is now spreading via heterosexual contact. The virus incapacitates the T-helper lymphocytes and thus prevents proper functioning of the cell-mediated immune response. It uses the T4 antigen as its receptor and employs the T-cell’s genomic apparatus to replicate, destroying the cell as it does so. It can also infect reticuloendothelial cells (including Langerhans cells) and B-cell lymphocytes.
