The Use of Chimpanzees in Biomedical and Behavioral Research

Prior to Simian Immunodeficiency Virus (SIV)-infected macaques becoming the ‘model of choice’ in the 1990s, chimpanzees were widely used in AIDS vaccine research and testing. Faced with the continued failure to develop an effective human vaccine, some scientists are calling for a return to their widespread use. To assess the past and potential future contribution of chimpanzees to AIDS vaccine development, databases and published literature were systematically searched to compare the results of AIDS vaccine trials in chimpanzees with those of human clinical trials, and to determine whether the chimpanzee trials were predictive of the human response. Protective and/or therapeutic responses have been elicited in chimpanzees, via: passive antibody transfer; CD4 analogues; attenuated virus; many types and combinations of recombinant HIV proteins; DNA vaccines; recombinant adenovirus and canarypox vaccines; and many multi-component vaccines using more than one of these approaches. Immunogenicity has also been shown in chimpanzees for vaccinia-based and peptide vaccines. Protection and/or significant therapeutic effects have not been demonstrated by any vaccine to date in humans. Vaccine responses in chimpanzees and humans are highly discordant. Claims of the importance of chimpanzees in AIDS vaccine development are without foundation, and a return to the use of chimpanzees in AIDS research/vaccine development is scientifically unjustifiable. Points of Interest from Study:  Despite 85 different vaccines having been tested in 197 clinical trials, protection and/or significant therapeutic effects had not been demonstrated by any of those vaccines in humans, in spite of prior successful trials for most vaccines and vaccine types in chimpanzees.  AIDS-related chimpanzee studies fell by nearly 90% from 1998 to 2005.  VaxGen’s AIDSVAX B/B and AIDSVAX B/E vaccines were the first to complete Phase III clinical trials. Comprising HIV gp120 proteins from different strains, AIDSVAX B/B failed to protect more than 5000 trial participants at high risk of HIV infection, and AIDSVAX B/E failed to provide protection against HIV infection for over 2500 users of injected drugs, despite repeated booster immunizations. An Examination of Chimpanzee Use in Human Cancer Research Bailey, J. (2009). Alternatives to Laboratory Animals (ATLA), 37(4), 399-416.