Importantly, Treg cell depletion allowed naive wild-type CD4+ T cells to induced anemia in FV-infected recipients (Figure 6E), the severity of which was milder than anemia induced by naive EF4.1 TCRβ-transgenic CD4+ T cells, in line with the reduced frequency of FV-specific clones in the former population. The gene discussed is CD4; the disease is anemia (phenotype).