Simian-human immunodeficiency virus (SHIV) containing the nef/long terminal repeat region of the highly virulent SIVsmmPBj14 causes PBj-like activation of cultured resting peripheral blood mononuclear cells, but the chimera showed No increase in virulence.

SIVsmmPBj14 is a highly pathogenic lentivirus which causes acute diarrhea, rash, massive lymphocyte proliferation predominantly in the gastrointestinal tract, and death within 7 to 14 days. In cell culture, the virus has mitogenic effects on resting macaque T lymphocytes. In contrast, SIVmac239 causes AIDS in rhesus macaques, generally within 2 years after inoculation.

Significance of macrophage tropism of SIV in the macaque model of HIV disease.

Microglia, alveolar macrophages, and Langerhans cells are representatives of cells of macrophage lineage that are susceptible to infection with HIV-1 and they play important roles in the pathogenesis of AIDS dementia, lymphoid interstitial pneumonia, and systemic viral invasion from mucosal surfaces, respectively. In contrast, elimination of CD4+ T cells with resultant development of immunosuppression and AIDS is thought to be reflective of the exclusive tropism of the virus for CD4+ T cells. Examination of these concepts in macaques infected with molecularly cloned strains of SIVmac suggested that all strains of the virus are both macrophage- and lymphocyte-tropic and that all aspects of pathogenesis including loss of CD4+ T cells are dependent on infection in both cell types.

Induction of T-lymphocyte adhesion by histidine-proline-rich glycoprotein and concanavalin A.

Histidine-proline-rich glycoprotein (HPRG) is a plasma protein which binds to a specific receptor on T-lymphocytes and represses T-cell activation and proliferation. In the presence of Concanavalin A (Con A), HPRG causes human T-lymphoblastic MOLT-3 cells and a fraction of normal human peripheral blood lymphocytes to attach to the culture dish and significantly change morphology by either extending processes or becoming elongated at the poles, respectively. HPRG and Con A are just as effective at inducing MOLT-3 attachment in a soluble or an immobilized form.