By contrast with the first and second generations of vaccine, made from live viruses and viral proteins, the new type of vaccine, which is non-infective, uses DNA to carry one or several varieties of viral gene. The genes are introduced into the body to be absorbed by cancer cells, where they produce antigens and generate the desired immune reaction.
不同於以活病毒和病毒蛋白成分製成的第一代與第二代疫苗，如今正在研發中的第三代疫苗，是用質體 DNA 攜帶一個或多個病毒基因，這種疫苗不具感染性，打入體內被細胞吸收後，會在裡面製造抗原，引起免疫反應，是相當理想的疫苗。