What is HIV?

HIV stands for human immunodeficiency virus. Originally isolated in Paris in May 1983 by Luc Montagnier, HIV belongs to a group of viruses called retroviruses.

Viruses copy their genetic material into the genetic material of human cells, meaning infected cells stay infected for the rest of their lives. Viruses cannot replicate outside a living cell. When a virus replicates, it may do so with accuracy or with error (known as a mutation). Because of viral mutation, or errors in copying itself, HIV can vary from one individual to another. The ability of the virus to change is also how it can, at times, evade suppression by antiretroviral therapy.

The genetic material of a virus can contain either DNA or RNA. Chickenpox, herpes simplex, and hepatitis B are all DNA viruses. RNA viruses use the enzyme reverse transcriptase to transcribe the RNA virus into a DNA copy of itself. The retroviral DNA is then capable of integrating into the host chromosomal DNA. HIV and hepatitis C are both RNA viruses.

Through mechanisms still not fully understood, HIV prevents the body's immune system from working properly. Normally, the immune system fights off infection. However, HIV is able to infect CD4 T-cells, key cells that co-ordinate the immune system's fight against infection. Many CD4 T-cells are destroyed by being infected and even uninfected CD4 T-cells may no longer work properly.