HIV Emerged Earlier Than Previously Thought?

UNITED STATES: "HIV/AIDS Emerged as Early as 1880s"
National Geographic News (10.01.08):: Amitabh Avasthi

New research suggests that AIDS among humans occurred at least three decades earlier than previously thought. Rapid urbanization in west-central Africa "was the turning point that allowed the pandemic to start," said Michael Worobey, an evolutionary biologist at the University of Arizona-Tucson and the study's lead author.

Previous research has indicated that HIV-1, Group M - globally, the most prevalent strain of the virus - originated in Cameroon in 1930 and began to reach epidemic levels in Leopoldville, Belgian Congo (now Kinshasa, Democratic Republic of the Congo) about 1960. The new study suggests the virus was probably being transmitted among humans in sub-Saharan Africa between 1884 and 1924.

While analyzing tissue samples, the researchers took note of one from Kinshasa in 1960 that contained fragments of HIV-1 RNA. When they compared the 1960 virus with the oldest known strain of HIV-1, from 1959, they found significant differences. A mathematical model showed that at least 40 years of evolution must have elapsed to account for the 1960 strain's differences from the 1959 sample. The most recent common ancestor of both strains can be traced to 1908, according to the model.

Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, which funded the study with the National Institutes of Health, said the finding "solidifies our understanding of the timetable of how this virus emerged from the chimpanzees to establish itself as a human infection." "This confirms that this was a virus that was lurking around for many decades before it exploded into the human population to become a noticeable pandemic, as opposed to something that started in the '70s or '80s," Fauci said.

Scientists see a clear understanding of the epidemic's origins as critical both to controlling HIV/AIDS and responding to future emerging viruses.

The report, "Direct Evidence of Extensive Diversity of HIV-1 in Kinshasa by 1960," was published in Nature (2008;455(7213):661-664).