We focussed on the production of cytokines typically associated with the major CD4+ve Thelper cell subsets (IFN-γ/Th1; IL-4/Th2; IL-17A/Th17; IL-10/Treg) and proliferation of PBMC in a model of intranasal infection of non-pregnant sheep with C. abortus that results in abortion in the subsequent pregnancy [11]. This evidence concerns the gene CD4 and infection.