Grant: Fellowship - PA: Biomedical / Clinical HIV/AIDS Research

The Public Health Agency of Canada estimates that by the end of 2005, about 58,000 Canadians were living with HIV-AIDS, and that approximately 2500 more people are infected each year. Anti-retroviral drug treatment for HIV has been very effective in reducing transmissibility of the infection and in improving both quality and length of life. However, the HIV virus can mutate to forms that are resistant to drug treatment. Therefore the emergence and transmission of drug-resistant (DR) strains of HIV is of great concern to both patients and health care workers. Patients infected with DR strains face limited treatment choices and severely shortened life span. They can also transmit drug-resistant strains to previously uninfected individuals: the prevalence of transmitted DR HIV in Canada, in 2004, was near 10%. We are interested in studying the emergence and transmission of DR during an HIV epidemic. We will take a multi-level approach to this problem, combining within-host and epidemic modeling. At the within-host level, we are looking at how and when DR strains may appear in treated patients. We are particularly interested in the role of latently infected cells as a potential reservoir for DR strains. We will develop a stochastic model in order to evaluate probabilities of developing a DR infection. At the epidemic level, we will develop a network model in order to understand how DR strains might spread through a populations. Each node in such a network represents an individual, which we will associate with the within-host dynamics, thus bridging the host and population levels. Our results will create a deeper understanding of how DR develops. We will use our model to evaluate the efficacity of early vs late treatment in limiting the evolution of HIV infection into a DR strain. If we find that early treatment is best, this will provide further support for early detection and regular HIV testing to prevent the emergence and transmission of DR strains of HIV.