Altogether, these results show that neutralization of IL‐27 in the acute phase of the infection profoundly affected PbT‐II cell phenotype and function during chronic phase, although PbT‐II cells from anti‐IL‐27 mAb‐treated mice were phenotypically indistinguishable from control group during acute phase except for a slight but significant increase in CD127+ cells in anti‐IL‐27 mAb‐treated mice. The gene discussed is IL27; the disease is infection.