Temperature and developmental stage govern intestinal susceptibility to human coronavirus 229E.

Abstract

Human coronaviruses have been primarily associated with upper respiratory tract infections, yet cases of gastrointestinal symptoms in COVID-19 patients have highlighted their potential to cause systemic disease. Here, we detail the infection of intestinal epithelia by an endemic, low-pathogenic human coronavirus, human alphacoronavirus 229E, using patient-derived human intestinal enteroids (HIEs) from donors of various ages. Using fetal, pediatric, and adult HIEs, we investigated how physiologically relevant temperatures: 37 °C and 32 °C, reflecting gastrointestinal and upper-airway conditions, respectively, modulate epithelial responses and viral infection dynamics. We show that there is temperature-dependent transcriptional reprogramming, indicating strong temperature-dependent regulation of virus replication and epithelial responses. Among the seasonal coronaviruses tested, only HCoV-229E productively infects HIEs. At 32 °C, HCoV-229E replicates efficiently in enteroids from all donor ages and releases high titers of infectious progeny. In contrast, at 37 °C, productive replication is largely confined to fetal and a subset of pediatric tissues, revealing a developmental and temperature-sensitive restriction on infection. Confocal and flow cytometry analyses identify enterocytes as the primary target cells for HCoV-229E. Furthermore, we show that camostat, a serine protease inhibitor, significantly reduces HCoV-229E replication in HIEs, confirming a critical role for host serine protease activity. Collectively, these findings establish HIEs as a relevant model for HCoV-229E-host interactions and reveal temperature- and age-dependent determinants governing intestinal permissiveness to this seasonal coronavirus.