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National Antivisection Society

3. The Scientific Steering Committee’s five examples of diseases of concern

Posted: 13 July 2007

(a) AIDS

SSC: “The etiologic agent HIV-1 is an example of a virus with a very complex interaction with the immune system and a very limited host range. It only readily infects humans and to a lesser extent chimpanzees”.

ADI Response:

  • Although HIV can infect chimpanzees it does not induce disease in them. Human beings are the only species to have been found to be susceptible to HIV38.
  • In America, in 1995, the NCRR (National Center for Research Resources) introduced a moratorium on the breeding of their chimpanzees for research.
    • When the AIDS epidemic began, it was thought that the chimpanzee would be an ideal model of the disease. It was not; the moratorium came shortly after it was established that the chimpanzee model was not helpful in the study of AIDS vaccines, as chimpanzees suffer little harm from HIV. In 2007 the director of NCRR announced that the NCRR had decided to make the moratorium permanent39.

    • Researchers in Denmark and the USA have highlighted the need to reconsider the use of primates in research. The team compared genes found in humans to their equivalent genes in chimpanzees. They found that the genes which differ the most between humans and chimpanzees are those related to immune defence and cancer development40.
    • In order to infect primates with HIV, a hybrid HIV-SIV strain was generated in the laboratory, calling it SHIV. SIV is a closely related monkey retrovirus that also induces AIDS in inoculated animals. Non-existent in nature, the SHIV strain infection in monkeys is an extremely rapid and exaggerated model of HIV infection in humans41.
    • The UK’s scientific ethics body, the Nuffield Council on Bioethics notes that
      • HIV is a virus that has “proved difficult to treat and cure, despite the availability of animal models” and, “…no single animal model perfectly reproduces the symptoms of HIV-1 infection and development of the disease in the diverse human population”42.

      • One scientist stated “more studies are needed not because chimpanzees are good models for human diseases, but rather because they are surprisingly bad models in many instances, for example, HIV infection progressing to AIDS and P.falciparum malaria.”43.

      SSC: “The Rhesus macaque has been well characterized… to allow for the study of vaccine efficacy in an outbred primate species”.

      ADI Response: others do not agree–

      • One research team commented “Animal models cannot determine whether a vaccine will be effective against HIV-1 infection of humans; only phase III trials in humans can do so”44.
      • Another team, intending to highlight the value of the primate model for AIDS research conceded that, “Animal models can only be validated after successful trials in humans”...we are as yet unable to validate any of the currently used nonhuman primate models for vaccine in research.."It would be risky to extrapolate vaccine success based solely on results of challenge studies in nonhuman primates”45.

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