Thereby numbers of CD4+ T cells in the mesLN increased during infection in BALB/c (average number: 1.0 × 107 cells) and C57BL/6 mice (5.5 × 106 cells) and by trend (p = 0.1) in F1 mice (average number: 7.9 × 106 cells). This evidence concerns the gene CD4 and infection.