HOW do you deal with a virus which attacks the immune system that is trying to fight it off? It鈥檚 a question HIV researchers have been trying to 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) 鈥� the monkey equivalent of HIV.
The vaccine is a departure from the usual approach, which is to prime the body鈥檚 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.
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Instead, of the Children鈥檚 Hospital of Philadelphia in Pennsylvania and his colleagues injected the monkeys鈥� 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. 鈥淚nstead of expecting the person鈥檚 own immune system to do the job, we鈥檙e giving them their own supply of 鈥榦ff-the-peg鈥� antibodies,鈥� Johnson says.
鈥淚nstead of using their own immune system, we鈥檙e giving them a supply of 鈥榦ff-the-peg鈥� antibodies鈥�
鈥淚t is now 85 weeks since all nine macaques received their jabs, followed by injections of SIV, and they still haven鈥檛 suffered any infections,鈥� he says. 鈥淏y contrast, four of six unvaccinated animals died of monkey AIDS鈥� (Nature Medicine, ).
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 鈥渢he virus always wins in the end鈥�, he says.
Given such a strong proof of principle, the team is already gearing up for clinical trials, with four potential 鈥渟uperantibodies鈥� from people who are HIV-resistant.
鈥淲ithin two to three years, we would hope to have this in the clinic,鈥� says Wayne Koff, senior vice-president of research and development at the , which is collaborating with Johnson on this next phase. 鈥淚t will be a tremendous test of the concept to see if what has protected the monkeys pans out into people,鈥� he says.
