Inhaled pattern recognition receptor agonists promote inducible epithelial resistance against murine betacoronavirus...

Coronaviruses can cause serious disease in humans and animals. They are often difficult to study due to the variability of the disease as well as safety concerns related to biosafety requirements. Here, we use a biological safety level (BSL) 2-compatible murine betacoronavirus (MHV-A59), which infects multiple organs, to study the respiratory phase of disease and subsequent systemic dissemination. We asked whether inducible epithelial resistance, activated by the combination of pattern recognition receptor agonists Pam2CSK4 (Pam2), synthetic diacylated lipopeptide, + oligodeoxynucleotide (ODN) M362, can limit both pulmonary infection and systemic spread of disease. Prophylactic exposure with Pam2 + ODN improves survival and reduces extrapulmonary viral burden, including in the liver, consistent with limited systemic spread. Stopping the infection at the level of the lungs is associated with improved physiological outcomes and increased protection for the mice. We further characterize the response of the epithelial cells to infection and treatment and demonstrate modulation of epithelial gene expression, including attenuation of virus-induced responses, to better understand the mechanisms of protection and how these responses may be leveraged against future infectious agents.NEW & NOTEWORTHY This study establishes a BSL 2-compatible murine betacoronavirus model to investigate respiratory and systemic disease. We show that inducible epithelial resistance via Pam2 + ODN improves survival, preserves lung function, and reduces extrapulmonary viral burden. Mechanistically, Pam2 + ODN reprograms lung epithelial gene expression, reversing virus-induced transcriptional responses. These findings support epithelial-targeted, pathogen-agnostic strategies to limit both pulmonary and systemic consequences of respiratory viral infection.