Detection of bovine coronavirus in myocardial tissue of a naturally infected calf

Coronaviruses are RNA viruses with high genomic plasticity and with the ability to infect a wide range of animal hosts, including humans. Among them, the highly pathogenic SARS-CoV-2, a betacoronavirus, is the causative agent of severe respiratory infection, and has also been associated with extrapulmonary manifestations, including cardiac involvement. BCoV, another betacoronavirus, is a major pathogen of cattle, primarily affecting the respiratory and enteric systems. Herein, a case of death in a calf with clinical signs consistent with BCoV infection is described. Potential cardiac involvement was further investigated, motivated by evidence of SARS- CoV-2 associated cardiac pathology in humans. Pulmonary and cardiac tissues were subjected to molecular and histological analyses. BCoV RNA was detected in both heart and lungs while immunohistochemical and immunofluorescence analyses confirmed BCoV antigen presence in both tissues. Cardiac detection was mainly observed in the conduction system and the endothelial cells. This study provides the first evidence of cardiac detection of BCoV and lays the foundation for future research on the closely related human coronavirus OC43, contributing to the One Health approach.