Kaushal Baid, University of Saskatchewan

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Fighting & Responding

Background: Middle East respiratory syndrome coronavirus (MERS-CoV), first identified in Saudi Arabia in 2012, causes severe respiratory disease in humans. Vesper bats, known to harbor betacoronaviruses, are considered potential ancestral reservoirs of MERS-CoV. However, the infection dynamics of MERS-CoV in these bats are not well understood. This study investigates viral replication, shedding, clinical symptoms, pathology, and immune responses in Eptesicus fuscus, an insectivorous vesper bat, following experimental MERS-CoV infection. Methods: E. fuscus bats were infected or mock-infected with 10⁵ TCID₅₀/mL of MERS-CoV and sampled at 2-, 4-, 7-, and 14-days post-infection. Body weight and temperature were monitored, and tissues were examined for gross pathology. Antiviral gene expression was assessed using qPCR and bulk RNA sequencing. Virus-specific neutralizing antibody titers were measured by micro-neutralization assays. Results: Infected bats exhibited no weight loss or fever. MERS-CoV RNA was detected in multiple tissues from infected bats, indicating productive infection. Interferon-related genes were upregulated, suggesting activation of antiviral responses. No gross lung pathology or tissue damage was observed in infected animals. Infected bats developed virus-specific B cell responses, including neutralizing antibodies. Conclusions: MERS-CoV can productively infect E. fuscus bats without causing clinical disease or lung pathology, despite evidence of viral replication and antiviral immune activation. These findings support the use of E. fuscus as a viable experimental model for studying MERS-CoV and MERS-CoV-related viruses' infection dynamics, tissue tropism, and host immune responses in bats. This model may help uncover mechanisms of viral tolerance and persistence in reservoir hosts.