TLR mRNA expression in infected U937 cells. The TLR mRNA expression was studied with quantitative real-time PCR at 5h and 24h p.i. A) TLR3 expression. The d120 infection significantly increased the TLR3 expression at 5h p.i. when compared to HSV-1(KOS)-infected cells (5 moi). R7041 infection increased TLR3 expression at 24h p.i. when compared to HSV-1(F)-infected cells (1 moi). B) TLR4 expression. The d120 infection decreased the TLR4 mRNA expression level at 24h p.i. when compared to its parental virus HSV-1(KOS)-infected cells (1 and 5 moi). TLR4 expression level was significantly decreased in d120-infected cells at 24h p.i. (1 and 5 moi) as well as in R7041-infected cells at 5h p.i. (5 moi), but increased in HSV-1(KOS) infection (1 moi) at 5h p.i. when compared to uninfected cells. C) TLR9 expression. No significant differences were seen in TLR9 expression levels. The bars represent the mean level of TLR mRNA expression normalized to β-actin ± standard deviation (SD) from at least three independent experiments. The statistical significances of the differences in TLR copy numbers in comparison with the d120 parental virus HSV-1(KOS) or HSV-1(F) are marked as * (*:p<0.05) and in comparison with uninfected cells as # (#:p<0.05).