Human immunodeficiency virus (HIV) is a lentivirus (a member of the retrovirus family) that causes acquired immunodeficiency syndrome (AIDS), a condition in humans in which progressive failure of the immune system allows life-threatening opportunistic infections and cancers to thrive. Infection with HIV occurs by the transfer of blood, semen, vaginal fluid, pre-ejaculate, or breast milk. Within these bodily fluids, HIV is present as both free virus particles and virus within infected immune cells. Synonyms: Polyclonal HIV1 RT antibody, Anti-HIV1 antibody, HIV-1 antibody, Anti-RT HIV-1 antibody, HIV 1 antibody, Human Immunodeficiency Virus 1 antibody.