A new SIV vaccine has been developed; it’s a recombinant vector vaccine using an adenovirus ‘prime’ to carry SIV genes, and interestingly, the booster is a recombinant Pox virus! After the regimen, infections in rhesus monkeys were reduced by 80% from the experimental group to the unvaccinated control. The researchers found high titres of glycoprotein Abs in vaccinated monkeys and believe these were important in preventing infection, although 12% of said monkeys still did not clear the virus. Humoral responses may also be effective against HIV infection, as noted in the RV114 (Thai) trial, where the 30% of patients who were successfully immunized ‘produced the highest levels of antibodies against HIV’s envelope protein” (GP120). Researchers hope that recombinant vaccines may also work for HIV, but given the species barrier, these SIV vaccines may still not be a good model for developing one for the human virus.
Fun facts about the experiment;
* The monkeys were challenged with SIV intrarectally
* Some Rhesus monkey MHC Class I alleles correlate with stronger control of SIV, thus they were screened out of the study
* There was an 18% genetic difference between the vaccine and challenge strains
Nature News Article