On the Trail of an AIDS Vaccine

This week, scientists from around the world gathered in Boston for the 12th annual AIDS Vaccine 2012, a conference devoted to research towards an HIV vaccine. The mood inside the convention center was optimistic about the current status and future of AIDS vaccine research.

There were presentations and discussion on every aspect of the search for a shot that could end the AIDS epidemic – from the attempts to understand all aspects of HIV transmission to the challenges of conducting vaccine clinical trials in the context of other HIV prevention methods that have already or are beginning to show promise.

These methods include PMTCT, male circumcision, microbicides, pre-exposure prophylaxis (or PrEP) and treatment as prevention.

The majority of the conference was devoted to presentations on the approaches currently being considered for developing a vaccine and to build on the success, however modest, of the AIDS vaccine trial in Thailand reported at this conference three years ago. Vaccines for other infectious diseases frequently work by stimulating the production of immunity from antibodies against the infectious agent, allowing for the antibodies to block transmission or infection. 

We know that HIV-infected individuals can make strong antibodies, and much recent work has gone into isolating and characterizing these highly effective antibody responses.

However, despite the testing of many vaccine approaches specifically designed to elicit strong antibody responses in humans, we have been largely unsuccessful in raising these antibodies though vaccination.

But we may be getting closer to this important goal for an HIV vaccine.

Exciting work presented this week by Bill Schief of the Scripps Research Institute showed that we may be able to work backwards from a highly desired specific antibody to the exact piece of HIV that would be necessary to stimulate these antibody responses in the context of a vaccine.

In addition, scientists are showing that an HIV vaccine will require the induction of T-cells to fight HIV. 

New work presented by Louis Picker of the Oregon Health & Science University showed that vaccine-elicited T-cells may in fact be able to completely eradicate an AIDS-like viral infection in an animal model –the first time that this level of virus control has been ascribed to a particular part of the immune response.

On another front, EGPAF-funded scientists and others presented work at the conference designed to help us understand more about how HIV is transmitted from an HIV-positive mother to her baby during breastfeeding.

These scientists are also focusing on what protects breastfeeding infants from becoming infected, despite daily exposure to HIV for up to two years. Work by the labs of Maureen Goodenow at the University of Florida and Grace Aldrovandi (former EGSA) at Children’s Hospital, Los Angeles, showed that some types of antibody responses might actually enhance transmission, pointing to the correct type of antibody necessary for the observed protection.

We are certainly learning more and more about how to make a safe and effective HIV vaccine.
Research this year and in the future will get us ever closer to this elusive goal.  

Jeffrey T. Safrit, Ph.D., is EGPAF's Director of Clinical and Basic Research, and is based in Los Angeles, CA.