Sally, read your article with great interest, but this is my view that I submitted to Nature and was rejected, but later presented by someone who reviewed my paper. This may sound hypothetical, but an absolute logical truth is there which all of us working on HIV should take a lesson from it and stop looking for HIV organs in primates because they will never find one.
In so many years we have not been able to find HIV in other mammalian species, simply because all of which have their own immunodeficiency viruses such as Feline immunodeficiency virus (FIV), mouse immunodeficiency virus (MIV), Equine immunodeficiency virus (EIV), Simian immunodeficiency virus (SIV- monkeys, chimps, Gorilla). Tracing the history of these viruses we find that new world monkeys do not have these viruses, suggesting that these viruses came into existence after the continental drift. Moreover, if a virus from old world monkeys is introduced into a new world monkey, they die of AIDS-like disease again suggesting that these NW monkeys die because of lack of adaptation that old world monkeys have developed over many millennia, and the virus has evolved in concert with the host. Also, this further suggests that the old world monkeys must have died of AIDS prior to becoming adapted to SIV.
Another important point here is that various primate species have their own viruses, and these species maintain very strict sexual segregation, therefore their viruses too show distinct sequences specific to a species, such as Tantalus monkey SIV, Sabaeus monkey SIV, etc., and the list goes on.If such segregation of SIV exists in nature among the primate species, it is highly unlikely a jump has occurred because the virus could not have changed to a sequence we see in HIV today. This is also clear from the HIV-1 genome from the lymph node tissue of a man in the Democratic Republic of Congo who has been embedded in wax since 1966, and it does not change the dogma at all. Also, it needs to be clarified that the interspecies transmission of SIV happens constantly in nature through biting and bruising, but all these primate species in the old world are adapted to-an interesting fact to be noted.
If you see the natural infection in Regional primate centres where researchers have become accidentally infected with SIV through biting or bruising have shown seroconversion, but have never developed disease. These data have never been published because of the confidentiality.
Again, taking HIV and putting them into Chimps and other primates do not make them sick. It is the artificial virus SHIV (half HIV and half SIV) that makes them sick. Thus, these two arguments point at one thing that human form of HIV is possibly our own. Retroviral genomes and endogenous retroviruses are a part of human evolution, and these viruses have co-evolved in human gremlin carrying out diverse functions. It is likely that HIV-like virus exited the germline in recent human history, as it did in other mammalian species over many millennia and that is why we have failed to find an HIV-like virus in nature. Human lab experiments in cells have also shown that the Chimpanzee SIV (CIV) cannot infect human cells productively or vice versa. Even though the CIV is closest to the human analogue, it has species-specific attribute to it. It again stresses the fact that immunodeficiency viruses have evolved with the host and are species-specific.
Hope scientists working on HIV and SIV can take lessons from these natural observations, and initiate a new thinking to look for the origins of HIV. It is long overdue, and because of stale view explored over and over again we have not been able to create a vaccine for HIV.

Nitin Saksena, Ph.D
HIV researcher