Grant: Operating Grant: Innovative Biomedical and Clinical HIV/AIDS Research

It is widely assumed that a successful HIV vaccine will elicit protective antibodies to prevent infection. The development of potent antibodies is regulated by a population of white blood cells called CD4 T cells. These CD4 T cells must recognize parts of the vaccine components to be stimulated and exert their functions. However, the CD4 T cell responses stimulated by the candidate vaccines that have been tested thus far are quite variable. CD4 T cells exist in everybody in different "flavours". Our preliminary results suggest that the diversity of pre-existing CD4 T cells in people who get vaccinated plays a big role in the way they will respond to vaccine shots. We propose here to examine the pre-existing "repertoire" of CD4 T cell responses that are able to recognize two new types of HIV vaccines that will begin to be tested in people soon. We will also test our hypothesis by using cells from blood samples obtained pre- and post vaccination in three clinical trials of HIV vaccines. We expect that these studies will help us understand why people can respond so differently to vaccination, and inform us about how to design better vaccines that give more consistent results in humans.