In search of an HIV vaccine
This search is one that has eluded researchers globally, although South African scientists are well placed to make a significant contribution.
Professor Anna-Lise Williamson at the University of Cape Town has made significant progress through her Vaccinology Research Chair. She headed the first research group in Africa to have produced two candidate HIV vaccines that progressed from concept to clinical trials locally and in the United States.
Her continued research has been into developing novel ways to deliver vaccines, primarily for HIV, using vectors such as the tuberculosis vaccine, BCG and poxviruses (members of the family Poxviridae).
“The main challenges are to develop effective vaccines that can be manufactured cheaply enough for large-scale rollout. There is a greater chance of doing so for poxviruses, making them appealing vaccine vectors,” says Williamson.
Poxviruses are also common in animals, so she has extended her research into creating vaccines for use in veterinary applications. Williamson is also recognised on the continent for her work into human papillomaviruses (HPV, the main cause of cervical cancer). She recently identified a connection between HPV and HIV that increases the chances of HIV-positive females developing cervical cancer. Her work is important in understanding these linkages, particularly because cervical cancer is a preventable disease.
The University of KwaZulu-Natal’s Professor Thumbi Ndung’u is also actively searching for an HIV vaccine through his Systems Biology of HIV/Aids Research Chair. His line of attack is to study the full spectrum of viral control, including “elite and viremic controllers”, a term for people who have an innate ability to control the HI virus without antiretroviral treatment.
He hopes that his studies into their mechanisms of viral immune control will lead to novel vaccine designs that can induce the same response in uninfected persons who are exposed to the virus or even to infected patients. Some headway has already been made in identifying vulnerabilities in the virus that can be used to counter it, although this is a long-term project.
Ndung’u is also studying patients during the early stages of infection to understand which immune responses are most effective in controlling the virus, how the virus responds to immune responses and why the immune system ultimately fails to control the virus. This knowledge would then be used to improve the immune system and make it more effective against the virus.
He says: “The Research Chair has been crucial in developing local skills in the fields of virology and immunology and has helped graduate more than 15 doctoral and seven Master’s students, and in mentoring several postdoctoral fellows. This expertise has largely been retained, with some graduates continuing their research work through appointments to faculties at local and African universities, while others are in companies requiring high-level technical expertise and some are in public sector health laboratories.”
The Chair has also enabled Ndung’u to conduct research into other biomedical fields such as HIV/Aids drug resistance and immune responses in HIV/TB co-infection (in cases where HIV and tuberculosis co-exist).
“The support from the Research Chair Initiative has made an incalculable contribution to furthering our work on HIV vaccine development, and has allowed us as South African researchers to become active participants in trying to resolve the most significant public health challenges of our generation,” says Ndung’u.
Professor Caroline Tiemessen at the University of the Witwatersrand is following a similar approach in that she is trying to understand the characteristics that enable elite controllers to naturally suppress the HI virus. In addition, she has for many years been studying mother-to-child transmission of HIV, to understand what protects some infants from getting infected despite their exposure to the virus.
This work mainly tries to understand the immune responses and genetics of adults and children in order to identify factors that contribute to these phenomena.
Although her HIV Vaccine Translational Research Chair only commenced in April 2013, Tiemessen has made good headway in building research capacity and collaborations to broaden the reach of her team’s work. This has resulted in multidisciplinary research from the fields of virology, microbiology and molecular biology as well as taking on additional post-graduate students.
“One of the core areas of our research is into the genetics of African populations, because it is critical to developing effective vaccines. We are conducting baseline studies to compare black and Caucasian groups to help identify genetic differences that could affect the delivery and efficacy of these vaccines.”
The group is also studying differences in gender, because women’s bodies are generally more susceptible to autoimmune disease but are better able to fight infectious diseases.
This supplement has been paid for by Department of Science and Technology and its contents signed off by the DST and the National Research Foundation.