We report that differentiated bovine airway epithelial cells are susceptible to avian, swine, and human influenza A viruses. This indicates that cows are a potential host of avian and mammalian influenza A viruses and may be implicated in the transmission of influenza viruses to other animal species and humans.

Bovine respiratory disease complex (BRDC) is a multifactorial and globally prevalent condition involving a combination of viral and bacterial pathogens, as well as environmental stressors. Viral agents often initiate infections in the upper respiratory tract (URT), predisposing animals to secondary bacterial infections and severe clinical manifestations. Among the key viral contributors to BRDC are bovine viral diarrhea virus (BVDV) and bovine herpesvirus 1 (BHV-1). In this study, submerged liquid cultures of undifferentiated bovine nasal epithelial cells (BNECs) were employed to investigate mono- and co-infections with BVDV and BHV-1. Epithelial barrier integrity was assessed to evaluate the cytopathic effects of BHV-1, while viral replication and release were quantified. Both viruses demonstrated polarized release, and BHV-1 infection exhibited a pronounced cytopathic effect. Notably, a preceding BVDV infection did not alter the progression or outcome of BHV-1 infection in this in vitro model. These findings suggest that primary BNEC cultures represent a valuable and physiologically relevant tool for studying viral dynamics and interactions associated with BRDC.