With over 40 million people worldwide currently living with HIV/AIDS and millions more becoming infected each year, a group of scientists is calling for a coordinated global HIV vaccine enterprise to speed up the development and testing of promising candidates.
In an article in the June 27 issue of Science, the authors emphasize the urgent need for an HIV vaccine, and outline a plan to accelerate research. Without a vaccine, if current trends continue, 45 million new people will become infected by 2010 and 70 million people will die by 2020, the World Health Organization and the Joint United Nations Programme on HIV/AIDS predict.
The group of scientists, brought together by lead author Richard Klausner of the Bill and Melinda Gates Foundation, proposes a new network of about six to ten coordinated vaccine development centers, each devoted to a particular vaccine approach. These centers should increase the pace of development, decrease overlap between laboratories, and get more candidate vaccines into clinical trials.
Though researchers have made progress in understanding HIV and the immune system, we are still far from having an effective vaccine, says Caltech president and coauthor David Baltimore. Developing an HIV vaccine is especially difficult because HIV has protected itself very effectively against the most powerful weapon of the human immune system -- antibodies. Vaccines for other diseases rely on antibodies, which neutralize an invading virus, but the antibodies made against HIV are poor at neutralization.
Another approach is to try to elicit T-cell immunity against HIV. Vaccines have generally not been targeted to T-cells, which kill cells that have been infected by a virus. "We're trying to do something that has never been done before," says Baltimore.
Though researchers have made progress on both approaches, a vaccine remains elusive. Several candidates are being tested, but so far only one, made by VaxGen, has made it to a phase III clinical trial, and it proved ineffective. (Vaccines must go through a three-stage testing process before they are approved. Phases I and II are smaller trials intended primarily to test the safety of the vaccine; phase III is a larger trial with high-risk participants to determine the efficacy of the drug. The entire process usually takes five to seven years.)
The authors of the Science paper also propose a series of vaccine science consortia to work on fundamental science questions. For instance, says Baltimore, researchers would like to better understand the structure of HIV surface proteins and the process of viral entry.
Because of the high cost of developing a vaccine, we cannot rely completely on industry, say the authors. A public-private collaboration is needed, with new funds from both sectors. The new vaccine development centers could cost billions of dollars.
Accelerated vaccine development will also require increased manufacturing capability, more standardized pre-clinical testing, less overlap between different labs, and more international clinical trials, say the authors.
Even with these efforts, Baltimore believes it will be at least five to ten years before an effective vaccine is available, if one can be developed at all. Nonetheless, given the severity of the HIV/AIDS epidemic-- AIDS now kills more people than any other infectious disease-- we should step up our efforts, rather than give in, says Baltimore. "Throwing in the towel is not an option. This is too important."
