Human astroviruses (HAstV) are major causes of gastroenteritis, especially in children, and there are no vaccines or antivirals currently available. Little is known about host factors required for their cellular entry. Here we utilized complementary CRISPR-Cas9-based knockout and activation screens to identify neonatal Fc receptor (FcRn) and dipeptidyl-peptidase IV (DPP4) as entry factors for HAstV infection in vitro. Disruption of FcRn or DPP4 reduced HAstV infection in permissive cells and, reciprocally, overexpression of these factors in non-permissive cells was sufficient to promote infection. We observed direct binding of FcRn, but not DPP4, with HAstV virions and the purified spike protein. This suggests that FcRn is a receptor for HAstVs while DPP4 is a cofactor for entry. Inhibitors for DPP4 and FcRn currently in clinical use prevented HAstV infection in cell lines and human enteroids. Our results reveal mechanisms of HAstV entry as well as druggable targets to limit HAstV infection.

人星状病毒 （HAstV） 是胃肠炎的主要原因，尤其是在儿童中，目前没有可用的疫苗或抗病毒药物。对其进入细胞所需的宿主因子知之甚少。在这里，我们利用基于 CRISPR-Cas9 的互补敲除和激活筛选来识别新生儿 Fc 受体 （FcRn） 和二肽基肽酶 IV （DPP4） 作为体外 HAstV 感染的进入因素。FcRn 或 DPP4 的破坏减少了允许细胞中的 HAstV 感染，反过来，这些因子在非允许细胞中的过表达足以促进感染。我们观察到 FcRn 与 HAstV 病毒粒子和纯化的刺突蛋白直接结合，而不是 DPP4。这表明 FcRn 是 HAstVs 的受体，而 DPP4 是进入的辅助因子。目前临床使用的 DPP4 和 FcRn 抑制剂可预防细胞系和人肠样体中的 HAstV 感染。我们的结果揭示了 HAstV 进入机制以及限制 HAstV 感染的成药靶点。