Healthcare Infection Prevention
Quest continues for a global AIDS vaccine
Progress, but no magic bullet against HIV
With approximately 95% of all new HIV infections now occurring in developing countries, the search for a "global" AIDS vaccine is increasingly critical. Some barriers have fallen, but the virus is an elusive target, said Gary J. Nabel, MD, PhD, director of the vaccine research center at the National Institutes of Health. "We more fully appreciate the global nature of HIV genetic diversity, an important consideration in developing a vaccine that can protect against a wide variety of genetically diverse viruses," he stated recently at a press conference in Washington, DC. "We have recently begun early phase clinical trial testing of a novel global vaccine developed at the Vaccine Research Center." The vaccine is directed at the three most globally important HIV subtypes or clades. It incorporates HIV genetic material from clades A, B, and C, which cause about 90% of all HIV infections globally, he said.
The vaccine is the first multigene, multiclade HIV vaccine to enter human trials. Researchers have made major advances in vaccine technology, including development of improved vaccine delivery systems (such as optimized DNA and novel viral vectors), and improved lab techniques to identify and measure specific immune responses.
"With the discovery of HIV 20 years ago and the demonstration that HIV is the cause of AIDS, it seemed that a vaccine would follow closely behind. Unfortunately, HIV is a virus that has evolved to thwart the immune system and will not be easily countered," Nabel said.
Scientists have learned much about the three-dimensional structure of the HIV envelope.
Armed with this knowledge, specific targets may be revealed for HIV vaccines that can stimulate a broadly neutralizing antibody immune response. "We also better understand how the HIV virus evades the body’s normal immune response and how the virus enters target cells. Although we have made extensive progress, only one candidate vaccine strategy — aimed at eliciting neutralizing antibodies to a soluble HIV envelope protein — has entered human phase III testing, and the recently released results from this trial did not demonstrate vaccine efficacy in the overall trial cohort. There is an urgent need to create and to systematically evaluate more candidate vaccines," he stated.
According to Nabel, a new approach might include the creation of multiple HIV vaccine development centers, each with adequate funding, structure, and resources to devote to a specific vaccine development need and product.
An expanded and integrated international clinical trials system also is needed, he added.
"Such an expanded global AIDS vaccine effort would be a major step toward accelerating successful HIV vaccine development," Nabel said.
With approximately 95% of all new HIV infections now occurring in developing countries, the search for a global AIDS vaccine is increasingly critical. Some barriers have fallen, but the virus is an elusive target, said Gary J. Nabel, MD, PhD, director of the vaccine research center at the National Institutes of Health.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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