A vaccine has been developed that protects non-human primates (monkeys) from SIV (Simian Immunodeficiency Virus), the monkey equivalent of HIV. Researchers reported in the journal Nature that this breakthrough could eventually lead to a vaccine for humans, protecting them from HIV.

Louis Picker, M.D., from the Vaccine and Gene Therapy Institute (VGTI) in Oregon, and team produced a vaccine that programs monkeys' immune systems to respond more rapidly to the presence of SIV. Researchers from the International AIDS Vaccine Initiative and the National Cancer Institute-Fredick were also involved in this research.

They tested the vaccine candidate on rhesus macaque monkeys using a monkey with SIV. Over half of the monkeys that received the vaccine controlled virus replication so well that very sensitive tests could not identify any signs of SIV.

After more than twelve months, the majority of them still have control over the virus, steadily losing any signs of initial infections. The unvaccinated monkeys, on the other hand, developed the monkey equivalent of AIDS.

It appears that the vaccine triggers an immune response that completely clears SIV from the initially infected monkeys, the authors explained. This is not the case with antiretroviral therapy that only manages to control the disease - it does not eliminate the virus from within the immune systems' own cells.

The VGTI researchers have spent over a decade working on a vaccine candidate. This one is unique because it uses CMV (Cytomegalovirus) as the means of getting the vaccine into the body. They chose CMV because most humans are already infected with this virus, which stays in the body for like.

The team assumes that if CMV were used as a vector it could maintain permanent resistance against HIV, by programming effector memory T-cells to be on a perpetual lookout for HIV. Effector memory T-cells are part of the body's immune system.

Dr. Picker said:

"The next step in vaccine development is to test the vaccine candidate in clinical trials in humans. For a human vaccine the CMV vector would be weakened sufficiently so that it does not cause illness, but will still protect against HIV."

This research was financed by the International AIDS Vaccine Initiative and the NIH (National Institutes of Health).

"Profound early control of highly pathogenic SIV by an effector memory T-cell vaccine"
Scott G. Hansen, Julia C. Ford,Matthew S. Lewis, Abigail B. Ventura, Colette M. Hughes, Lia Coyne-Johnson, Nathan Whizin, Kelli Oswald, Rebecca Shoemaker, Tonya Swanson, Alfred W. Legasse, Maria J. Chiuchiolo, Christopher L. Parks, Michael K. Axthelm, Jay A. Nelson, Michael A. Jarvis, Michael Piatak, Jeffrey D. Lifson & Louis J. Picke
Nature DOI: 10.1038/nature10003