Interestingly, interfering with CD28 costimulation prior to secondary infection with N. brasiliensis in infected tamoxifen-treated CD28−/loxCre+/− mice had a profound impact on the recruitment and/or expansion of central memory (CD4+CD62LhiCD44hi) and effector memory (CD4+CD62LloCD44hi) T cells, as indicated by significantly reduced numbers compared to infected C57BL/6 mice (Fig. 3C). The gene discussed is CD4; the disease is infection.