LPS-loaded virions can trigger TLR4 signaling through IRF3 activation. (A) IRF3 activation from TLR4-expressing (Tlr4+/+) THP1-Dual cells was measured by luciferase activity. Bars are mean ± SD of four different virus stocks across two to three independent experiments. Statistical significance was evaluated with one-way analysis of variance (α = 0.05) and Tukey’s correction for multiple comparisons. From left to right: n = 8, n = 12, n = 12, n = 14, n = 10, n = 12, and n = 12. ns, non-significant; ***P = 0.0003; ****P < 0.0001. (B) IRF3 activation from TLR4-KO (Tlr4-/-) THP1-Dual cells. Data are mean ± SD of two independent experiments using four different virus stocks. From left to right: n = 4, n = 8, n = 7, n = 4, n = 4, n = 8, and n = 8. (C) Secreted CCL5/RANTES was measured by ELISA from stimulated (24 h) THP-1 cells. Data are mean ± SD across two independent experiments with four different virus stocks. Statistical significance was evaluated as in (A). From left to right: n = 8, n = 8, n = 8, n = 4, n = 4, n = 8, and n = 8. ns, non-significant; ***P = 0.0005; ****P < 0.0001.