Vaccination consisted of two DNA inoculations at months 0 and 2 to prime the vaccine response and then two booster inoculations at months 4 and 6. The booster vaccine was MVA, an attenuated poxvirus expressing HIV proteins. Six months after the last vaccination, both vaccinated and unvaccinated animals were exposed to SIV through 12 weekly exposures, resulting in an 87 percent per exposure efficacy and 70 percent overall protection. Over the next two years uninfected animals were exposed multiple times in two more series, resulting in an 82 percent per exposure efficacy during the second series and an 84 percent per exposure efficacy during the third series. "Repeated challenges in animals are used to mimic sexual transmission," says Robinson. "The hope is that the results in the nonhuman primate models will translate into vaccine-induced prevention in humans." "It is impressive to note that protection could be observed against both neutralization sensitive and neutralization resistant viruses," says Amara. Neutralization is the process by which some antibodies can block virus infection.
April 3, 2012
Original web page at Science Daily