STAT1 and viral infectious disease: On the other hand, it is known that under normal conditions, the response par excellence to viral infections in the placenta is mainly mediated by type I interferons (INF-Is) which help activate the anti-viral state and counteract viral infection; however, DENV has the ability to inhibit the INF-I signaling pathway owing to its non-structural proteins NS4A/NS4B, NS2B, and NS5, which inhibit the activation of STAT-1 and 2, thus reducing the anti-viral response [149,150].