This documentary presents the argument that journalist Edward Hooper makes in his book "The River", that SIV became HIV through a widespread oral polio vaccine (OPV) trial in the Belgian Congo in the late 1950s. OPV is made using tissue cultured primate cells. Generally these are from the organs of Asian monkeys not so closely related to humans as African primates. Even using distant relatives to Humans, the possible oncogenic virus SV-40 contaminated OPV and infected people.
This movie argues that Hillary Koprowski oversaw a field trial that used chimp organs as the basis for OPV production. Koprowski denies that claim, and has produced a vial of the same lot that he says was used in the vaccine trial, that is SIV-free. The movie counter-argues that those lots were used as seeds for local production of OPV, in chimp cells. The film backs up the claim with records of chimp capture and sacrifice, and interviews with lab techs that say that they harvested the organs for tissue culture, saw it being performed, and even labeled the product as "vaccine".
The movie also chronicles how the scientific community has stonewalled the people who have supported this hypothesis about the origin of AIDS, when the "bush meat" argument seems less likely.
A talking head says that it was unlikely that Koprowski shipped the gallons of OPV overseas. That should be easy to check. Even if the documentation was sketchy back then, it should be easy to tell, from notebooks and animal handling records, if Koprowski was producing millions of doses of OPV in the US, or if he was producing thousands of vials of seed virus for local production in the Congo. For all the minutiae of chimp handling in the Congo, I'm disappointed in the lack of investigation on the US side, and that's the film's biggest flaw, the one that makes it seem the most one-sided.
It's a thought-proving documentary now showing on Sundance, and you should check it out.
Kubrick 7-2, in an earlier comment, wanted to know when the earliest case of HIV was reported. To the best of my knowledge, it was in 1959, from the Congo. The 1930s date of the origin of AIDS was, I believe, based on the known mutation rate of HIV and the divergence from the strains of SIV thought to be the ancestors of HIV-1. The film claims that hypothesis is being challenged.
jbowmore notes that we are still using animal serum for vaccines, though there is an artificial answer. I don't know the full details of modern OPV production, but they are surely tested for non-OPV viral presence, and are likely not grown from primary primate cell lines (i.e. ground up organs) but from immortal cell lines. So much safer than in the late 50s. A recombinant vaccine, which the movie suggests, is not guaranteed to work and would be very expensive to develop. The Salk vaccine is closer to a recombinant vaccine, and it was replaced by the OPV in large part because the OPV conferred better immunity.