TNF and infection: In the present study, the expression of CCL5 and TNF-α mRNA in A549 cells infected with RSV wt rose to 574% and 380% of the 18 hpi expression levels, respectively (Figure 3), by 24 hpi, whereas expression of these same mRNAs at 24 hpi with the ∆NS1 virus was approximately the same for RSV wt infection at 18 hpi (Figure 3).