Quest for an Effective HIV Vaccine Presents New Possibilities, Challenges
May 18 marks the 10th annual HIV Vaccine Awareness Day — an opportunity to reflect on the more than two decades of progress worldwide in the search for a safe and effective HIV vaccine.
Schmalfeldt: May 18 marks the 10th annual HIV Vaccine Awareness Day — an opportunity to reflect on the more than two decades of progress worldwide in the search for a safe and effective HIV vaccine. Dr. Gary Nabel, director of the Dale and Betty Bumpers Vaccine Research Center at the National Institute of Allergy and Infectious Diseases, explained the challenges facing researchers as they look for a vaccine.
Nabel: HIV as a target is really a formidable target. It's very difficult to make a vaccine against this virus because, in fact, it's not one virus — it's millions of different viruses. So whenever we try to develop any kind of vaccine, we have the problem of trying to provide enough of a stimulus to the immune system that it might recognize the millions of different variants that any individual could be infected with in the world. As if that weren't enough, the virus has also acquired the ability to evade neutralization by the immune system. And it seems to do this by changing the shape of some of the critical proteins on the surface of the virus. There's one particular protein that it uses to attach to cells called the "envelope", and that envelope protein never stays in the same form on the surface of that virus as it would during the process of infection. So, basically, we're dealing with a lot of diverse viruses and we're dealing with a virus that has learned to camouflage itself by changing its shape, and that's what really makes it a tremendous challenge.
Schmalfeldt: Dr. Nabel said the search for a vaccine is something of a medical detective story, with different leads being followed as new clues are discovered. The chase is complicated by the fact that this culprit — the HIV virus — is different from any virus medical researchers have ever done battle against.
Nabel: HIV has infected now more than 60-million people. And in contrast to almost every other virus that we've generated vaccines for, we don't have any documented cases of natural immunity to this virus. Typically when we manufacture a vaccine that's what we count on — we count on examples from nature to follow, and then we mimic what nature normally does. So, in a way, we're really developing a new paradigm for vaccine development. And it's really one of the greatest scientific challenges of our generation — perhaps in medical history — because this virus has shown that, despite the fact that it can infect large, large numbers of people, the human body has not yet figured out a way to counteract it.
Schmalfeldt: The NIAID launched the first HIV vaccine trial in Bethesda, Maryland 20 years ago. And along with the challenges researchers face, the quest for an effective HIV vaccine presents some exciting new possibilities. For instance, according to scientists at the NIAID, the first successful preventive HIV vaccines, if administered prior to HIV infection, may reduce HIV levels in the body, thereby delaying the progression to AIDS and the need to start retroviral drugs. These vaccines might also reduce the chance that a person infected with HIV would pass on the virus to other people. Dr. Nabel said he's optimistic about the future.
Nabel: Just being in a position to be able to do those trials now with pretty good vaccine candidates, and with some of really the latest technology both in vaccine production and in measurements of human immune responses is quite a tribute to the many dedicated scientists and actually the many dedicated vaccine volunteers who've participated in the studies that are ongoing.
Schmalfeldt: Vital to the search for an effective vaccine is the collaboration between the academic and private sector, government researchers, non-governmental organizations and the thousands of volunteers who have decided that they want to be part of the generation that ends AIDS. One of those volunteers is "Amber " — to maintain her privacy, we're just using her first name. She explained why she chose to be part of the search for a vaccine.
"Amber": I know that there's a heavy burden to find a vaccine for HIV and I wanted to be part of that discovery or that solution to HIV. So, you read a lot in papers about how HIV affects different families and the communities, especially myself as an African-American woman, just the rates of HIV are higher in that population and in other minority populations. And I just wanted to have some part in finding the solution.
Schmalfeldt: "Amber" believes that the day isn't far off when researchers will announce a safe and effective vaccine for HIV. She says there will be a certain sense of pride and satisfaction for having helped in the search.
"Amber": It's going to feel great. I'm going to feel, like, this is wonderful. They've gotten enough people involved, they were able to do what they needed to do from volunteers like myself, and I'll just feel really elated and glad that there's finally a solution.
Schmalfeldt: In the coming years, several major clinical trials testing different vaccine candidates and approaches will be completed. Later this year, there are plans to launch an 85-hundred person trial in the United States, Latin America, the Caribbean and Sub-Saharan Africa. Although none of these trials is expected to lead immediately to a licensed vaccine, Dr. Nabel said each study adds to the body of knowledge that helps shape future vaccine efforts.
Nabel: This is going to be a long road. I think that these initial studies will hopefully allow us to put a stake in the ground to say that it is possible to generate immunity and to tell us what mechanisms may be most effective. And then it will be up to us to refine that going down the road. So we've made a lot of progress, we're doing things that simply were not possible five years ago. And in the realm of vaccine development, the kinds of progress you've seen in that time frame are truly unprecedented. Having said that, we need to dig in for the long haul because this will be an iterative process. We will build on the knowledge that we gain in each step
Schmalfeldt: For more information on how you can be part of the generation that ends AIDS, log on to www.bethegeneration.org. From the National Institutes of Health, I'm Bill Schmalfeldt in Bethesda, Maryland.
About This Audio Report
Reporter: Bill Schmalfeldt
Sound Bite: Dr. Gary Nabel
Topic: HIV Vaccine