In Tanzania we often get asked about the history of the HIV virus. There are some theories about its origin, but how the virus moved from chimpanzees–where it is thought to have originated as a form of SIV, the simian immunodeficiency virus, similar to HIV–to humans, then from a relatively small infected population, to the widespread epidemic it is today is unknown. We advocate no particular history of the virus to our students, but focus our discussion on prevention and testing.
However, knowing about the history of the virus enables scientists to understand its patterns and can help efforts to develop vaccines. By sequencing the DNA and RNA of a 50-year-old biopsy sample from what is now The Democratic Republic of the Congo gives evidence that HIV has infected humans for over 100 years, instead of 50 years as previously thought. This article discusses the uses of studying the history of the virus in order to enhance prevention.