Temporal transcriptomic and microbiome changes in American bison during experimental SARS-CoV-2 challenge.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to pose a threat to humans as well as domestic and wild animals. The variability in severity of clinical signs, the zoonotic potential, and the host-specific response to infection contribute to the persistence of circulation of disease. In wildlife species, white-tailed deer have been shown to be more permissive to infection than bovids. However, among bovids, American bison have shown a greater susceptibility than cattle. In this study, we investigate the transcriptomic response to experimental SARS-CoV-2 infection in bison over time. Substantial numbers of differentially expressed genes were identified between pre- and 2, 5, 7, 14, and 21 days post-inoculation. Kyoto Encyclopedia of Genes and Genomes and Gene Ontology term analysis identified associations with immune response, inflammatory response, and viral infection including COVID-19. Ingenuity Pathway Analysis of the coronavirus pathway highlighted differences in signaling at days 2 versus 21 post-inoculation. We additionally examined changes in the nasal microbiome of bison over the course of experimental infection, which suggested an increase in opportunity for secondary infection causing pathogens such as Mannheimia. Collectively, this study presents a profile of bison transcriptomic response to SARS-CoV-2 infection and continues to expand our understanding of variation in host response.