New vaccine shows promise in stopping HIV

Researchers in the United States have found that a new vaccine can protect macaques against the monkey equivalent of HIV known as SIV, offering protection to 13 of 24 rhesus macaques treated in the experiment.

The vaccine was still effective 12 months later in 12 of the 13 monkeys.  The researchers said the work, published in Nature, might “significantly contribute” to the development of an effective HIV/AIDS vaccine, the BBC reports.

The vaccine works by stimulating the production of a certain type of blood cell called “effective memory T-cells,” which may remain vigilant in the body long after an infection has abated.

Professor Louis J. Picker of the Vaccine and Gene Therapy Institute in Oregon, the lead author of the study, compared the cells to armed soldiers at the ready.

“There are soldier that are back at the base with their rifles in the shed, and then you have the guys out in the field,” Picker said, according to the BBC.

Picker said there was evidence that the vaccine, which used the genetically modified rhesus cytomegalovirus, all but eradicated traces of the macaque form of HIV, which he said was “unprecedented.”

While researchers in the field, like Professor Sir Andrew  McMichael of Oxford University, welcomed the study, they said safety issues would need to be addressed before similar approaches could be tested in humans.

"I'm excited by the science because it really does demonstrate that it may be possible to eradicate the HIV virus by a strong immune response," McMichael said, according to the BBC. “But at the same time I'm scratching my head how to take this approach into humans. CMV is not totally benign, it does cause a number of diseases. If you're giving people something you're not going to be able to get rid of should it cause problems, then that's quite a difficult risk to manage."

Picker said that the issues of safety would be addressed in forthcoming work. He pointed out that early forms of the smallpox vaccine also carried risks to humans.

"On one level, 99 percent of people in sub-Saharan Africa are CMV-positive and half the people in the developed world are, so we know at lot about it and it's mostly non-pathogenic, except in vulnerable populations like pregnant women,” Picker said, according to the BBC. “We're fully aware to make it available to humans, then the next step is to make a virus which retains or has an enhanced ability to make effector memory cells, but no longer has the capacity to infect vulnerable parts of the population."