Cholesterol 25-hydroxylase (CH25 H) is a key enzyme regulating cholesterol metabolism and also acts as a broad antiviral host restriction factor. Porcine deltacoronavirus (PDCoV) is an emerging swine enteropathogenic coronavirus that can cause vomiting, diarrhea, dehydration and even death in newborn piglets. In this study, we found that PDCoV infection significantly upregulated the expression of CH25H in IPI-FX cells, a cell line of porcine ileum epithelium. Overexpression of CH25H inhibited PDCoV replication, whereas CH25H silencing using RNA interference promoted PDCoV infection. Treatment with 25-hydroxycholesterol (25HC), the catalysate of cholesterol via CH25H, inhibited PDCoV proliferation by impairing viral invasion of IPI-FX cells. Furthermore, a mutant CH25H (CH25H-M) lacking hydroxylase activity also inhibited PDCoV infection to a lesser extent. Taken together, our data suggest that CH25H acts as a host restriction factor to inhibit the proliferation of PDCoV but this inhibitory effect is not completely dependent on its enzymatic activity.

胆固醇25-羟化酶（CH25 H）是调节胆固醇代谢的关键酶，并且也是广泛的抗病毒宿主限制因子。猪三角冠状病毒（PDCoV）是一种新兴的猪肠致病性冠状病毒，可引起新生仔猪呕吐，腹泻，脱水甚至死亡。在这项研究中，我们发现PDCoV感染显着上调了猪回肠上皮细胞系IPI-FX细胞中CH25H的表达。CH25H的过表达抑制PDCoV复制，而使用RNA干扰的CH25H沉默则促进PDCoV感染。用25-羟基胆固醇（25HC）处理胆固醇（通过CH25H进行催化）可通过损害IPI-FX细胞的病毒入侵来抑制PDCoV增殖。此外，缺乏羟化酶活性的突变体CH25H（CH25H-M）在较小程度上也抑制了PDCoV感染。两者合计，我们的数据表明，CH25H作为抑制PDCoV增殖的宿主限制因子，但这种抑制作用并不完全取决于其酶促活性。