It was noted that the percentage of IL-17+ Vγ4+ T cells increased rapidly after infection and even reached the peak at day 3 p.i. and then quickly restored to the basic level at day 7 p.i. All these above results demonstrated that lung Cm-infected Vγ4+ T cell is the main γδ T cell subset secreting IL-17 at the very early stage of Cm lung infection. The gene discussed is IL17A; the disease is infection.