From an alert reader:

 

Three separate analyses of oral polio vaccine used in the 1950s in Africa deflate the theory that such a vaccine could have ignited the AIDS epidemic by containing virus-infected chimpanzee cells.

 

References:

 

Berry, N., et al. 2001. Analysis of oral polio vaccine CHAT stocks. Nature 410(April 26):1046.

 

Lancou, P., et al. 2001. Polio vaccine samples not linked to AIDS. Nature 410(April 26):1045.

 

Poinar, H., M. Kuch, S. Paabo. 2001. Molecular analyses of oral polio vaccine samples. Science 292(April 27):743.

 

Further Readings:

 

Christensen, D. 2000. HIV may date back to the 1930s. Science News 157(Feb. 12):109. Seppa, N. 2000. Old polio vaccine free of HIV, SIV. Science News 158(Sept. 23):203.