HIV likely to have infected humans before 1930, knocking polio vaccine theory

The theory that HIV was introduced into humans through live oral polio vaccine in the late 1950s took a knock today with the news that careful examination of the rate at which HIV sub-types have diverged over the years suggests that it is highly likely that HIV first entered humans during the early part of the 20^th century.

Using the equivalent of 512 supercomputers for a whole day to perform their calculations, Bette Korber and colleagues at the Los Alamos National Laboratory compared the genetic sequences of more than a hundred virus isolates, some dating from 1959 and the 1960s, to determine the average speed at which HIV sequences change over time. The group used this information to back-calculate the amount of time it would have taken HIV to mutate from the genetic sequence of SIVcpz, its nearest relative.

The calculations established that HIV-1 group M, the root of virtually all the HIV-1 sub-types found in humans, is highly likely to have entered humans from chimpanzees in Africa between 1910 and 1940. The calculations also found that the D sub-type (common in Africa) began to evolve before 1950, and that the B sub-type (common in Europe and North America) began to emerge from the D sub-type in the early 1960s.

However, Prof. Robin Weiss of the Windeyer Institute, University College, London, said that the findings did not completely rule out a role for polio vaccination campaigns in amplifying the epidemic, due to the re-use of needles.

A stimulating summary of debates about the origins of HIV can be found at http://weber.ucsd.edu/~jmoore/publications/HIVorigin.html

Click here to read stories posted throughout the week from the Seventh Retroviruses Conference

Click here for conference abstracts and video/audio feed of conference presentations.

Detailed summaries of each days' proceedings by leading clinicians are available at Medscape HIV/AIDS