In duck cells, by contrast, STAT-3 expression was significantly up-regulated (P < 0.05) by LPAI H2N3 and H5N1-tyEng91 virus infection; STAT-3 expression was not significantly affected (P > 0.05) by H5N1-tyTR05 virus infection (Figure 6D). This evidence concerns the gene STAT3 and viral infectious disease.