At day 8 after infection, we found that the frequencies and numbers of total and effector (CD44+ CD62L-) CD4+ T cells derived from Ddb1-TaKO (CD45.1+ CD45.2+) BM was much lower compared with that derived from WT (CD45.2+) BM (Figures 2B–G). The gene discussed is CD44; the disease is infection.