HIV vaccine turns muscle into antibody factories
HOW do you deal with a virus which attacks the immune system that is trying to fight it off? It’s a question HIV researchers have been trying to
This coloured transmission electron micrograph (TEM) shows a section through the cell membrane of a T-lymphocyte white blood cell (T-cell). The "bubbles" are budding Human Immunodeficiency Viruses (HIV)
solve for years, and now they may have come up with a solution: bypass the immune system altogether.
Nine macaques have been protected against the monkey version of HIV with a novel vaccine that sidesteps the monkey immune system. Instead, the vaccine turns monkey muscles into factories for churning out antibodies which kill simian immunodeficiency virus (SIV) – the monkey equivalent of HIV.
The vaccine is a departure from the usual approach, which is to prime the body’s immune system for attack by exposing it to a harmless version of the real pathogen. Thus primed, the immune system prepares for a real invasion by building its own stockpile of antibodies that target the pathogen.
Instead, Philip Johnson of the Children’s Hospital of Philadelphia in Pennsylvania and his colleagues injected the monkeys’ muscles with a harmless virus carrying genes for making immunoadhesins, antibody-like molecules pre-selected to attack SIV.
The viruses load the genes into the nuclei of muscle cells, which produce and churn out the immunoadhesins, potentially indefinitely. “Instead of expecting the person’s own immune system to do the job, we’re giving them their own supply of ‘off-the-peg’ antibodies,” Johnson says.
“It is now 85 weeks since all nine macaques received their jabs, followed by injections of SIV, and they still haven’t suffered any infections,” he says. “By contrast, four of six unvaccinated animals died of monkey AIDS” (Nature Medicine, DOI: 10.1038/nm.1967).
Johnson says the approach is especially suitable for combating HIV, which overwhelms the immune system that is supposed to fight it. With all conventional vaccines so far “the virus always wins in the end”, he says.
Given such a strong proof of principle, the team is already gearing up for clinical trials, with four potential “superantibodies” from people who are HIV-resistant.
“Within two to three years, we would hope to have this in the clinic,” says Wayne Koff, senior vice-president of research and development at the International AIDS Vaccine Initiative, which is collaborating with Johnson on this next phase. “It will be a tremendous test of the concept to see if what has protected the monkeys pans out into people,” he says.
Source New Scientist
Posted by Sakhile Malaba
on May 22, 2009. Filed under Science&Technology.
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