The origin of the human immunodeficiency virus HIV-1 is controversial. In his 1999 book The River: A Journey Back to the Source of HIV and AIDS, journalist Edward Hooper claimed that the chimpanzee simian immunodeficiency virus, the closest relative of HIV-1, was transferred to humans in the Congo between 1957 and 1960 via an oral vaccine against the polio virus. Hooper believes that chimpanzee kidney cultures were used in the preparation of the vaccine. In the 26 April Nature three independent studies provide evidence that effectively dismiss this claim.

Berry et al subjected two frozen stocks of the suspect vaccine to PCR analysis. They detected neither human nor simian immunodeficiency virus sequences (Nature 2001, 410:1046-1047). Instead, they found evidence of macaque mitochondrial sequences, suggesting that the vaccine was prepared from macaque, not chimpanzee cells.

In the second study Blancou et al performed a similar analysis on...