Although the basal levels of this population were higher in C57BL/6 animals, 2 weeks post-infection this CD4 subset significantly increased in BALB/c and SV/129 mice, while it did not change in C57BL/6 mice (Figure 1A, p ≤ 0.05 or p ≤ 0.01, compared with BALB/c or SV/129, respectively). The gene discussed is CD4; the disease is infection.