Figure 8

STAT-3 appears to regulate the pro-inflammatory response and promote virus replication in H5N1 virus infected chicken and duck cells. (A) Primary chicken embryo cells over-expressing phospho-STAT-3 showed a high phospho-STAT-3 expression while STAT-3 inhibitor S3I-201 treatment resulted in reduced phospho-STAT-3 protein expression in duck cells at 24 h following H5N1-tyEng91 virus infection (1.0 MOI). (B) phospho-STAT-3 over-expressing chicken cells showed a significant reduction in LITAF, IL6 and IL-8 mRNA expression with no significant change in IFN-α expression. (C) At 24 h following H5N1-tyEng91 virus infection, in STAT-3 inhibited duck primary embryo cells, significant increase of LITAF, IL-8 and IL-6 mRNA expression was detected with no significant change in IFN-α expression. Phospho STAT-3 over-expression in chicken cells increased viral replication at 24 h following H5N1-tyEng91 virus infection as evidenced by increased detection of virus NP (A), matrix gene mRNA (D) and infectious virus output in culture supernatant (E). STAT-3 inhibition did not significantly affect virus NP (A) matrix gene expression (D) or infectious virus production (E) at 24 h following H5N1-tyEng91 virus infection in duck cells. Relative mRNA expression was determined by real-time PCR to 18S rRNA. Data points are the mean of three biological replicates with error bars as standard deviation (*p < 0.05).