IL-4 level at 9th week (one week after infection) in vaccination group showed no significant difference with other two control groups, one possible explanation is either early infection induced Th1-polarized immune response that inhibit the Th2 levels or infection induced strong Th2 immune response in the control group, which covers up the slow increase of IL-4 levels in the vaccinated group. The gene discussed is IL4; the disease is infection.