CYP17A1 and viral infectious disease: The results showed that transcription of Cyp17a1 (the rate-limiting metabolic enzyme for testosterone and estradiol biosynthesis) gene was induced upon viral infection (Fig. S1c), but the mRNA level of Cyp19a1 (another rate-limiting metabolic enzyme for estradiol biosynthesis) gene was hardly affected by virus (Fig. S1c).