American researchers are claiming that at least one strain of the HIV virus which is thought to cause AIDS originated in some species of African monkeys.
Their claim gives weight to the theory among some observers that AIDS may have been spread to humans by the use of infected polio vaccine which had been bred from the kidneys of monkeys (WDDTY, vol 3 no 2).
Researchers at the Retrovirus Diseases Branch, Division of Viral and Rickettsial Diseases, Atlanta, Georgia, have discovered a second laboratory worker who has become infected with simian immunodeficiency virus (SIV), which has been shown to cause AIDS like symptoms in some species of monkeys.
This latest incident confirms that cross infection between humans and monkeys is possible.
Significantly, although the worker was shown to have SIV infection, he also responded positively to a test for HIV-2 infection, the common form of HIV infection in Africa, again reinforcing the link between the two viruses.
Two earlier studies have already shown that SIV and HIV-2 are very closely related, and an editorial accompanying the latest report states: "From a strict classification perspective, HIV-2 is simply an SIV strain."
The researchers conclude: "The risk of human infection with SIV is no longer merely hypothetical. Our findings support . . the idea . . that HIV-2 originated from SIV."