Virus That Causes AIDS May Be 100 Years Old

There's an interesting research finding published in Nature that HIV-1 Type M, the virus that causes most HIV and AIDS infections in the world, has been prevalent in human populations since at least 1908.

Worobey and his colleagues made the discovery while analyzing tissue samples collected between 1958 and 1960 from Kinshasa. One of them, acquired in 1960, contained bits of HIV-1 RNA, the virus's genetic material.

The researchers compared the 1960 virus with the oldest known HIV-1 strain, which was obtained in 1959 and evolved independently of the 1960 variant. They found that the 1960 version was significantly different.

Next the researchers constructed an evolutionary family tree of the HIV-1 virus, made up of both the 1959 and 1960 strains along with more than a hundred modern viral sequences.

Using a mathematical model, Worobey and his colleagues discovered that the 1960 strain must have been evolving for at least 40 years to account for the number of differences from the 1959 strain.

The model also traced the most recent common ancestor of both strains to 1908.