Scripps team lays ‘spectacular’ foundations for HIV vaccine

19 Jun

“A leap forward” has been made to develop a vaccine against HIV, claim the authors of two new studies that are published concurrently in the journals Cell and Science.

eOD-GT8 60mer immunogen
An immunogen called eOD-GT8 60mer could be effective as the first in a series of immunizations against HIV.
Image credit: The Scripps Research Institute

The aim of the research is to design a vaccine that elicits an immune response against HIV, producing antibodies that bind to the virus and prevent infection.

Vaccines typically use a dead or inactive version of the virus to provoke the production of antibodies. Because HIV is excellent at evading detection from the immune system, however – and because it has the ability rapidly mutate into new strains – HIV microbes are not effective for use in a vaccine.

Consequently, researchers have investigated the potential to use related proteins called immunogens to “train” the body to produce antibodies that can neutralize HIV.

The authors of the new study explain that this concept is a twist on the traditional booster shot, in which the patient is repeatedly exposed to the same immunogen.

The researchers behind the new studies found that an immunogen called eOD-GT8 60mer could be effective as the first in a series of immunizations against HIV.

This immunogen produces antibody “precursors” that the scientists explain possess some of the required abilities to recognize and block HIV.

The immunogen was designed by a team at The Scripps Research Institute’s (TSRI) International AIDS Vaccine Initiative (IAVI). “The results are pretty spectacular,” says Dennis Burton, scientific director of the institute.

Prof. Burton led the research project alongside TSRI colleagues William Schief (IAVI Neutralizing Antibody Consortium director) and Prof. David Nemazee.

Across the two studies, the researchers tested eOD-GT8 60mer in various mouse, rabbit and nonhuman primate models. In all models, eOD-GT8 60mer was effective in priming the necessary antibody response to block HIV.

Next, the researchers will investigate other immunogens that could work alongside eOD-GT8 60mer to contribute to a viable HIV vaccine.

Why have previous HIV vaccines failed?

In January, Medical News Today looked at a study that proposed an explanation for why experimental HIV vaccines are prone to “backfiring.” The authors of that study, from Emory University in Atlanta, GA, recommended that researchers should avoid developing vaccines that activate too many of the cells in mucosal tissues that the virus targets.

“One of the reasons why it has been so difficult to make an AIDS vaccine is that the virus infects the very cells of the immune system that any vaccine is supposed to induce,” suggested senior author Guido Silvestri, chief of microbiology and immunology at Yerkes National Primate Research Center at Emory.

Another study published in January, in the journal Nature, investigated training T cells to recognize, attack and subdue mutant strains of HIV that lie dormant in the body.

Explaining why this approach might solve some of the problems experienced by previous attempts to create a HIV vaccine, senior investigator Dr. Robert Siliciano, professor of medicine, molecular biology and genetics at the Johns Hopkins University School of Medicine in Baltimore, MD, said:

“We found that these pools of dormant virus carry mutations that render HIV invisible to the very immune cells capable of disarming it, so even when the virus comes out of hiding, it continues to evade immune detection.”

Written by David McNamee