<prompt> Human immunodeficiency virus HIV affects the immune response. The primary change brought about is:A gammaglobulinemiaDefect in cell-mediated immunityDefect in complement systemDefect in natural killer cells  <response>: HIV infects CD4 helper T-lymphocytes, macrophages and monocytes and leads to cell-mediated immune deficiency which predisposes to opportunistic infections and malignancies. 