In this clip of Gates, apparently from 2005, he is talking about a project involving an engineered virus which would immunize against the vmat2 gene, a gene he states which is indicative of religious extremism.or fanaticism. The name of the Project was FunVax .
According to Gates, religious extremism, like that responsible for fundamentalist attacks in the middle-east, is easy to test for; subjects are read a text in which God is mentioned. Normal subjects experience disgust, while religious fanatics do not show discomfort in brain scans, that is, that part of the brain responsible for religious fanaticism does not light up.
The plan was to kill the gene which was responsible for religious extremism, the vmat2 gene. The method of delivery was a virus, a respiratory virus. This project had been submitted at the time Gates addressed the CIA, he was quite confident it would be a very successful program.