While an AIDS vaccine would be a great addition to international healthcare provisions and is considered the Holy Grail for a number of medical researchers, it has not yet been discovered.
A study undertaken at Oregon Health & Science University's Vaccine and Gene Therapy Institute and published in the journal Nature Medicine revealed why inoculations against weakened versions of the Simian Immunodeficiency Virus (SIV) – which can cause AIDS in monkeys and is thought to be the source of the human epidemic – are too risky for use in humans, despite the fact that they could prevent later infection with virulent strains of the illness.
Furthermore, the research discovered why inactivated or severely compromised versions of SIV do not appear to have any beneficial effect on recipients at all.
It claimed that the protection caused by SIV vaccinations causes a persistent live attenuated version of the virus to infer protection from anti-viral T-cells that are found in lymphoid tissue.
Weakening SIV strains reduces levels of protection by preventing the persistence of the virus and as a result, HIV vaccines may have to remain in the body persistently in order for them to be effective.
It was found in the 1990s that a weakened version of SIV could protect many simians from being affected by the virulent strain of the condition, although the weakened SIV could still cause some monkeys to develop AIDS.
Scientists led by associate director of the Vaccine and Gene Therapy Institute Dr Louis Picker also revealed that the cytomegalovirus can be engineered to express HIV or SIV proteins and could be used to raise immunity against AIDS-causing viruses.
"We thought that understanding the mechanism responsible for the protection afforded by the too-dangerous-for clinical-use attenuated vaccine would allow us to design a vaccine that would be both effective and safe," Dr Picker said.
This research was funded by the International AIDS Vaccine Initiative, the Bill and Melinda Gates Foundation and the National Institutes of Health.