Painstaking research using modern genetic technologies has placed the origin of the HIV/AIDS pandemic sweeping the world today at somewhere between 1884 and 1924, much earlier than the 1930 point of origin previously estimated.  The same period of time saw rapid urbanization of Colonial Africa, a very opportune moment for a virus to jump from the wild into the human population.

Michael Worobey, assistant professor of ecology and evolutionary biology at the University of Arizona, Tucson, used fragmented genetic materials of the two oldest known specimens of the AIDS virus to delve deep into its evolutionary history to better pinpoint the moment in time before genetic mutations made these two samples different.  The journal, Nature, carries the findings of his meticulous research in its current issue.

A preserved tissue sample from 1959 and another from 1960 are the oldest known links to the beginning of the HIV-1 group M genetic sequence, the specific form of HIV infecting most people today.  Although both tissue samples provided only fragmented sections of DNA and RNA, Worobey used some of the most recently developed techniques to compare and analyze the two samples.

These two HIV samples, considered ancient by HIV/AIDS standards, were taken from patients, one a man and the other a woman, in Kinshasa, a city in today’s Democratic Republic of the Congo.  Kinshasa was a rapidly developing, colonial hub under Belgian dominion at the turn of the 20th century.

The genetic diversity of these two viral strains is thought to have taken about 40 years to differentiate genetically from their common ancestor. With this evolutionary timeline from which to work, Worobey says the original virus very likely existed in the human population around 1900.

Genetic diversity indicates the virus spread from chimpanzees to humans in the southeastern region of Cameroon.  Additional genetic research reveals a large number of people in the Democratic Republic of Congo carrying HIV by 1960, as well as people in the surrounding countries, including Congo, Gabon, Equatorial Guinea, and the Central African Republic, all areas experiencing rapid urbanization during the African Colonial Era.

Although HIV infection and AIDS were known in western Equatorial Africa since the turn of the last century, it wasn’t until 1981 that the virus had spread throughout the world and become better understood.  Its spread can be traced through changes in the human population, including the development of African cities and of more reliable and affordable means of global travel.

Worobey says the results of his study suggest reason to be optimistic about reversing the epidemic as we know it.  Knowing how the virus has spread over time and around the world, along with better means of testing and prevention, and more widespread use of antiretroviral drugs, contributes to the fight against further transmission of the virus.  Worobey says the virus’s weak spot, its tendency to be somewhat difficult to transmit from person to person, along with the new knowledge and improved treatment methods available today may provide a way to force the virus into extinction.

The National Institute of Allergy and Infectious Diseases and the David and Lucile Packard Foundation co-sponsored Worobey’s work.

Source: University of Arizona