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March 25, 2013
Transmission electron microsope image of a tissue culture cell line, infected with human immunodeficiency virus(HIV). HIV particles are 90-120nm. in diameter. HIV is the causal agent of acquired immune deficiency syndrome(AIDS). HIV is a retrovirus. The major host cell of HIV is the CD4 class of T lymphocytes and the virus somehow prevents normal division processes in these cells. Lymphocytes are very important to the body's immune functions. This viral infection process greatly compromises those immune functions, by the accelerated reduction of CD4 cells; this, in turn leads to AIDS. The procees of infection: (1) virus attaches to the cell via the CD4 molecue on the surface of the cell. The CD4 molecule on the lymphocyte acts as a cell surface receptor for HIV. (2) fusion of the virus envelope with the host cell membrane. (3) nucleocapsid, containing the genetic material, is carried into cytoplasm by endocytosis. JEOL 100CX TEM Credit: Louisa Howard