Focussing their research on simian immunodeficiency viruses (SIVs) in African nonhuman primates, scientists at the Yerkes National Primate Research Center, Emory University, have proposed an additional new approach to the AIDS vaccine research agenda in a commentary.
Their recommendations have outlined specific research priorities, and described how each may lead to a novel "out of the box" approach for developing an AIDS vaccine.
"Developing an effective AIDS vaccine has eluded scientists because the virus is tricky. Over 25 years after the discovery of HIV as the etiological agent of AIDS, no effective vaccine for the disease is available," Nature magazine quoted Dr. Guido Silvestri, a Yerkes affiliate scientist, as saying.
Most vaccines are based on conventional strategies that work by triggering the body's immune system to produce antibodies or killer T cells against the invading organism.
However, the AIDS virus attacks the immune system, leaving it handicapped and unable to mount an immune response.
Thus, conventionally designed AIDS vaccines that have been clinically assessed to date have failed to protect vaccinated individuals from HIV transmission or disease progression.
"To put it another way, a conventional vaccine strategy can be compared to using military might to destroy an enemy (in this case, the virus). A less conventional strategy could be to persuade the enemy not to attack you anymore," said Silvestri.
Alternative strategies may include development of AIDS vaccines that make infected individuals resistant to disease progression or resistant to the virus by reducing the number of cells the virus can infect.
Thus, the researchers have proposed that lessons learned from studying SIVs in their natural nonhuman primate hosts may provide a path to an effective AIDS vaccine.
SIVs are found exclusively in African nonhuman primate species and represent the original source of human immunodeficiency viruses (HIV-1 and HIV-2).
More than 40 species of African monkeys are infected in the wild with SIVs, but virtually none with the exception of chimpanzees progresses to HIV/AIDS or gets sick.
Evolution has enabled them to adapt to SIVs, and co-exist peacefully with chronic infection.
"Nature is giving us a message. Figure out how these monkeys can deal with the virus, and then maybe you can get humans to do the same thing," said Silvestri.
Particularly, Silvestri noted that additional studies of sooty managbeys - a medium-sized African monkey - are critical for the AIDS vaccine effort and understanding why SIV infection does not progress to HIV/AIDS.
SIV-infected sooty mangabeys develop a high viral load that does not increase their risk for developing AIDS and the SIV virus is rarely transmitted from mothers to babies.
The study has featured in the August issue of Nature Medicine.