There is renewed hope for the development of an HIV vaccine, thanks to increased funding, a better understanding of how the virus wreaks havoc in the body, and scaled-up testing in developing nations, researchers say.
But a vaccine, widely considered to be the best way to control the epidemic, is probably still years away -- mainly because scientists haven’t figured out how to prevent the rapidly mutating virus from evading the body’s disease-fighting immune system.
“In the last two years, a series of new initiatives from the Gates Foundation, the National Institutes of Health, and others have driven the science,” says Seth Berkley, MD, head of the International AIDS Vaccine Initiative. In the past month alone, vaccine research received a $287 million shot in the arm from the Bill and Melinda Gates Foundation.
“A few years ago, we had a couple of scientists tinkering in their lab and now we have collaborative worldwide efforts trying to solve the problem,” he says.
That said, there are still miles to go, says Françoise Barré-Sinoussi, MD, of the Institut Pasteur in Paris. “Everyone is looking for a vaccine, but we don’t even know if a vaccine is possible,” she says. Berkley, Barré-Sinoussi, and others spoke with WebMD about the state of vaccine development at the XVI International AIDS Conference here.
More Than 30 Vaccines in Testing
More than 30 experimental vaccines are now in various stages of human testing in more than 24 countries, with Merck & Co.'s product furthest along, Berkley says.
But even the study of that vaccine isn’t expected to produce results until 2008. And even if it does work, the vaccine will not protect against new infections, but rather prevent newly infected people from developing full-blown AIDS, he says.
That’s because the vaccine doesn't rely on the typical approach of teaching the body to recognize the virus and create antibodies to neutralize it before it infects cells.
Instead, the vaccine is designed to boost the ability of killer T cells (immune cells) to seek and destroy cells already infected with HIV.
“By giving it before infection, before the immune system becomes destroyed by the virus, the hope is that if a person does become infected, the vaccine will keep the virus in check and prevent disease progression,” Berkley says.
Whether it will work is still anyone’s guess. If it doesn’t, vaccine research will probably turn to the traditional approach of stimulating the production of antibodies to defuse the virus before it takes hold in the body, he says.
In fact, many researchers believe that an effective vaccine will need to boost both neutralizing antibody and killer T cell production, Barré-Sinoussi says.
Scaled-Up HIV Vaccine Studies
Recent advances in our understanding of how the virus mutates and how the immune system responds to HIV provide researchers with the greatest hope towards developing an effective vaccine, she adds.
Meanwhile, the geography of AIDS vaccine research and development continues to evolve, with four additional countries -- China, India, Rwanda, and Zambia -- beginning studies since 2005, Berkley says.
“The trials were fully enrolled in as little as one week,” he says. “We’re really scaling up and speeding up.”
On the basic science front, researchers funded by the International AIDS Vaccine Initiative recently unveiled a $2.2 million robot called CrystalMation. The device, which can rapidly screen protein molecules, will vastly accelerate the search for antibodies that can neutralize a wide range HIV strains, Berkley says.
Money is still an issue. While funding rose to about $759 million in 2005, more than $1.2 billion a year may be needed, he says.
Helene Gayle, MD, co-chair of the Global HIV Prevention Working Group, president and CEO of CARE USA, and co-chair of the International AIDS Conference, says that the vaccine is critical to stemming the epidemic of HIV, which infected 4 million people last year alone.
“We are fully confident we have a vaccine, but we’ve stopped predicting when: It could be five years, 10 years, or more,” Gayle says.
By Charlene Laino, reviewed by Louise Chang, MD
SOURCES:XVI International AIDS Conference, Toronto, Canada, Aug. 13-18, 2006. Seth Berkley, MD, CEO, International AIDS Vaccine Initiative.Françoise Barré-Sinoussi, MD, Institut Pasteur, Paris. Helene Gayle, MD, co-chair, Global HIV Prevention Working Group; president and CEO, CARE USA; co-chair, International AIDS Conference.