The fascinating story of HIV origin

I have reviewed a paper by Sharp and Hahn (2011) in YouTube for my students in Evolution course (I am a TA for Spring 2020). This paper is a complete review on the fascinating origin of HIV and how AIDS becomes a pandemic.

Here’s the YouTube video for your interest.

Monkey origin of HIV epidemic

This is a fascinating paper that discusses the origin of HIV viruses. In 1981, several homosexual young men died in a mysterious disease. They had rare opportunistic infections caused by apparently harmless bacteria. Later, this virus was named HIV or Human Immunodeficiency Virus and the disease was recognized as Acquired Immune Deficiency Syndrome or AIDS. In 1986 morphologically similar but antigenically different viruses isolated from other AIDS patients in Africa. A later study found that these viruses are genetically very similar to a simian immunodeficiency virus (SIV) causing immunodeficiency disease in the captive macaque. 

Later scientists searched for SIVs in other primates coming from Africa. They found that African Primates harbor SIV viruses which are non-pathogenic to the hosts. However, phylogenetically HIV virus is very similar to this SIVs but pathogenic to humans. Later scientists figured out that some SIVs crossed the species boundary from monkey to human several times causing the origin of HIV. HIV is not a single virus – they are a collection of similar viral strains. There are two big classes: HIV-1 and HIV-2. HIV-1 virus is are similar to SIV in chimpanzees and is HIV-2 virus is very close to the SIV virus in sooty mangabey.

If SIVs (mostly) non-pathogenic to non-human primates, what about the macaques: why they develop AIDS because of SIV infection? SIV is not natural in macaques hosts as they are Asian primates. SIVs are only found in African African monkeys or primates. 

Continue reading “The fascinating story of HIV origin”