World Without AIDS: Update on HIV Cure and Vaccine Research
July 22, 2014
Addressing the HIV Reservoir: Control
Controlling viral rebound, or having sustained virologic remission, without treatment could also be a viable "cure." The VISCONTI study, in which 14 patients were started on treatment during acute infection and subsequently showed no significant viral rebound after discontinuing treatment, gives us some interesting insight. Because they have very low levels of virus after a long period of stopping treatment (four to almost 10 years, depending on the person), they can be considered "post-treatment controllers." However, according to Fauci, another study that treated patients during acute infection showed that the level of viral control achieved after stopping antiretroviral therapy was limited.
Post-treatment control may be sustained by natural HIV-specific immunity, which appears to have been the case in the VISCONTI study. However, a number of studies are beginning to look into other ways to sustain post-treatment control, including the passive transfer of HIV-specific antibodies and therapeutic vaccination.
The Vaccine Challenge
Classic vaccines look to mimic natural responses to infection. However, a successful HIV vaccine needs to improve on these natural responses. HIV is very different because the body's natural response to infection is quite poor, especially considering:
Vaccine studies have been done since 1987, but none showed any efficacy until 2009, when a trial known as RV144 showed a modest 31% HIV risk reduction in participants taking a prime-boost vaccine containing ALVAC and AIDSVAX. This result reignited hope in the vaccine research field.
Currently, much of the field is focused on broadly neutralizing antibodies, which can target a number of vulnerable sites on the HIV envelope. But before we even think about an effective vaccine, a crucial question needs to be answered: Can these broadly neutralizing antibodies actually be used to prevent and treat infection?
According to Fauci, the answer is yes -- at least based on mouse and non-human primate models. Studies are underway or being planned to see if we can induce these broadly neutralizing antibodies in humans.
One of the strategies being explored is known as B cell lineage vaccine design. The idea is to go back to the classic vaccine paradigm, which mimics the body's natural response to infection. Because HIV mutates, it pushes the B cell lineage response to create broadly neutralizing antibodies -- but, as stated earlier, this can take at least two years, which is obviously too late to stop an initial infection.
Therefore, if we can somehow mimic HIV and use "iterative immunogens" for sequential immunizations -- not the same immunogen with boosts -- and if we can find a way to quickly induce broadly neutralizing antibodies, then we may have a successful vaccine. This approach is being actively pursued by researchers.
A World Without AIDS
"Even if we can induce sustained remission in a reasonable proportion of people, that would greatly enhance the treatment armamentarium. If we add a vaccine to our combination prevention -- with both of these, we may wind up with not only a possibility of a world without AIDS, but a durable world without AIDS," Fauci stated.
"My own children -- I have three daughters: 27, 25 and 22 -- they have never seen a world without AIDS. So perhaps if we attain these critical advances in science, they'll be able to tell their children about a world that once had AIDS that no longer does," he concluded.
Warren Tong is the research editor for TheBody.com and TheBodyPRO.com.
Follow Warren on Twitter: @WarrenAtTheBody.
Copyright © 2014 Remedy Health Media, LLC. All rights reserved.
This article was provided by TheBodyPRO. It is a part of the publication The 20th International AIDS Conference.
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