New HIV vaccine candidate ‘primes’ immune system

Scientists have designed a new experimental HIV vaccine candidate that may stimulate the immune system to block infection from the deadly virus.

New research led by scientists at The Scripps Research Institute (TSRI), International AIDS Vaccine Initiative (IAVI) and The Rockefeller University shows in mice that the vaccine candidate can stimulate the immune system activity necessary to stop HIV infection.

The findings could provide key information for the development of an effective AIDS vaccine, researchers said.

The research, published in concurrent studies in the journals Cell and Science, represents a leap forward in the effort to develop a vaccine against HIV, which has so far struggled to elicit antibodies (immune system molecules) that can effectively fight off different strains of the virus.

“The results are pretty spectacular,” said Dennis Burton, chair of the TSRI Department of Immunology and Microbial Science.

While many vaccines for other diseases use a dead or inactive version of the disease-causing microbe itself to trigger antibody production, immunisations with “native” HIV proteins are ineffective in triggering an effective immune response, due to HIV’s ability to evade detection from the immune system and mutate rapidly into new strains.

This challenge has led many researchers to believe that a successful AIDS vaccine will need to consist of a series of related, but slightly different proteins (immunogens) to train the body to produce broadly neutralising antibodies against HIV — a twist on the traditional “booster” shot, where a person is exposed to the same immunogen multiple times.

The scientists tested one of these potential proteins, an immunogen called eOD-GT8 60mer, a protein nanoparticle designed to bind and activate B cells needed to fight HIV.

The eOD-GT8 60mer was tested in mouse models to produce antibodies that resemble human antibodies.

Using a technique called B cell sorting, the researchers showed that immunisation with eOD-GT8 60mer produced antibody “precursors” — with some of the traits necessary to recognise and block HIV infection.

This suggested that eOD-GT8 60mer could be a good candidate to serve as the first in a series of immunisations against HIV, researchers said.

“The vaccine appears to work well in our mouse model to ’prime’ the antibody response,” added TSRI Professor David Nemazee.

In the Cell paper, researchers used the same eOD-GT8 60mer immunogen but used a slightly different mouse model.

“The immunogen again launched the immune system in the right direction,” said TSRI Professor William Schief.