AIDS / HIV
Infections caused by human immunodeficiency virus (HIV), pose severe health problems to the world's population. These health problems are particularly serious to people living in areas with poor hygiene, and in people with conditions causing compromised immunity. HIV currently infects approximately 33 million people worldwide, and their prevalence continues to rise. The disease caused by this virus is characterised by persistent infections with long incubation periods. It is during the long symptom-free incubation periods, when people are unaware that they are infected, that most of these infections will be transmitted from one person to another. Most infected individuals will develop AIDS, a disease that is characterized by opportunistic infections or development of cancers, because the HIV virus destroys the immune system.
Although some (relatively expensive) anti-viral drugs are available for HIV, they have not been able to stop the epidemic. Vaccination, which works by stimulating our immune system to combat infections, is the best approach for the prevention of this disease.
HIV can only infect humans and chimpanzees. However, in macaque species there is a HIV like virus (Simian Immunodeficient Virus: SIV) that gives a similar disease profile as HIV in humans. With this monkey model the BPRC studies the biology and pathology of the HIV virus. In order to investigate the efficacy of potential vaccine candidates against HIV, scientists have made recombinant SIV viruses expressing HIV envelopes (SHIV), which can successfully infect macaques. Immunogenicity studies for the various vaccine candidates can be evaluated in other species (mice, rats, cows), but these models have limited predictive value for human immune response and efficacy can not be evaluated. Therefore the SHIV rhesus model for AIDS is the phylogenetically most closely related model for human HIV infection in which vaccine immunogenicity, efficacy and disease progression to AIDS can be studied. Both SIV and SHIV rhesus infection models are used extensively at the BPRC.
For several years the BPRC has taken a multi-disciplinary approach by developing expertise in cellular, humoral and mucosal immunology, immunopathology, and molecular virology in non-human primate infection models in an international setting. These skills have been applied to rational immunogen design and pre-clinical evaluation of a number of leading HIV vaccine candidates.
Much of our HIV vaccine research is focused on finding the optimal combinations of HIV-proteins to use in these vaccine candidates, and finding the best way to deliver these proteins to the immune system. In this area of research we are developing vaccine strategies using new combinations of HIV-proteins. Additionally to the evaluation of prophylactic vaccines (intended to prevent infection), research is on-going towards the development and evaluation of new strategies for intervention/therapeutic vaccination (intended to strengthen the immune system of already infected individuals to improve their capacity to suppress the virus).
One important aspect of our work is to look for 'correlates of protection'. If a vaccine protects against a viral infection it is of utmost importance to know which mechanism is responsible for the protective activity. With this knowledge one could make better and /or stronger vaccines.