A New Tack for HIV Vaccines, and Why This Problem Is So Hard to Solve

Rhesus Macaque

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Attempts to create a vaccine for HIV have failed time and again partly because no one has been able to achieve the right vaccine balance — one that can spur the body into action, but not make a person sick. A new study in monkeys suggests a new solution: Vaccines could be more effective if they can be made to linger in the body.

Most vaccines work by introducing the body to a virus so it can build up defenses to fight off the invader. This works in one of two ways: Either the vaccines introduce a live, but modified, version of a virus — like the nasal-spray flu vaccine — or they introduce an inactivated version, which can still be enough to turn on the immune system.

In the early 1990s, researchers saw some promise with a slightly weakened version of simian immunodeficiency virus, the monkey equivalent of HIV. It conferred protection in some monkeys who were then exposed to the fully potent version of SIV. But other monkeys still developed full-blown AIDS, so the treatment was never considered safe enough to test on people. Researchers at Oregon Health & Science University set out to determine how this vaccine worked. They found that viral protection stemmed from T-cells (immune cells) that were maintained in the lymph nodes.

The takeaway: An HIV vaccine might have to persist in the body in order to work well. This might be possible by modifying other, less harmful viruses to perk up the T-cells, so that they're constantly on the alert, the study authors say. The paper is published online in Nature Medicine.