CD4 and infection: Relative to M. bovis BCG-stimulated CD4+ cells treated with scrambled siRNA, transfection of CD4+ cells with TLR2 siRNA prior to M. bovis BCG stimulation decreased infection with R5 virus from 6.2±0.7% to 3.6±1.0% (p = 0.005; Fig. 4b), and with X4 virus from 10.7±0.8% to 7.0±1.0% (p = 0.001; data not shown).