Human Immunodeficiency virus is a lentivirus 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. A lentivirus (lente-, Latin for “slow”) is a genus, a taxonomic rank used in the biological classification of living and fossil organisms, of viruses of the Retroviridae family. Lentiviruses can deliver a significant amount of viral RNA (ribonucleic acid) into the DNA of the host cell and have the unique ability among retroviruses of being able to infect nondividing cells. So they are one of the most efficient methods of a gene delivery vector, a DNA molecule used as a vehicle to artificially carry foreign genetic material into another cell, where it can be replicated and/or expressed. 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. HIV infects vital cells in the human immune system such as helper T cells (specifically CD4+ T cells), macrophages, and dendritic cells. HIV infection leads to low levels of CD4+ T cells. When CD4+ T cells numbers decline below a critical level, cell-mediated immunity is lost and the body becomes progressively more susceptible to opportunistic infections. Two types of HIV have been characterized: HIV-1 and HIV-2. There’s a difference between the two, HIV-1 is more virulent, more infective and is the cause of the majority of HIV infections globally. The lower infectivity of HIV-2 compared to HIV-1 implies that fewer of those exposed to HIV-2 will be infected per exposure. Because of its relatively poor capacity for transmission, HIV-2 is largely confined to West Africa.

The virus is passed from one person to another through blood-to-blood and sexual contact. An infected pregnant woman can pass HIV to her baby during pregnancy, delivering the baby during childbirth, and through breast feeding. HIV can be transmitted in other ways such as vaginal, oral sex, anal sex, blood transfusion, and contaminated hypodermic needles. Both the virus and the disease are often referred to together as HIV/AIDS. People with HIV have what is called HIV infection and as a result, some will then develop AIDS. The development of numerous opportunistic infections in an AIDS patient can ultimately lead to death. AIDS and its cause, HIV, were first identified and recognized in the early 1980s.

The difference between HIV and AIDS is that HIV is the virus which attacks the T-cells in the immune system and AIDS is the syndrome which appears in advanced stages of HIV infection. HIV is a virus, AIDS is a