Cassmann, E. D. | Search bioRxiv

bioRxiv2026

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

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, amongst 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-infection. KEGG and GO term analysis identified associations with immune response, inflammatory response, and viral infection including COVID-19. IPA analysis of the SARS coronavirus pathway highlighted differences in signaling at days 2 versus 21 post-infection. 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. SummarySARS-CoV-2 remains a threat to humans, domestic animals, and wildlife. Among bovids, American bison show greater susceptibility than cattle. We characterized the bison transcriptomic response to experimental infection across six timepoints, identifying extensive differential gene expression associated with immune, inflammatory, and antiviral pathways. KEGG, GO, and IPA analyses revealed activation of coronavirus-related signaling and shifts between days 2 and 21. 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. The results refine understanding of host responses to SARS-CoV-2 in bison.

immunology↗

bioRxiv2021

From Deer-to-Deer: SARS-CoV-2 is efficiently transmitted and presents broad tissue tropism and replication sites in white-tailed deer

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of coronavirus disease 2019 (COVID-19) in humans, has a broad host range, and is able to infect domestic and wild animal species. Notably, white-tailed deer (WTD, Odocoileus virginianus), the most widely distributed cervid species in the Americas, were shown to be highly susceptible to SARS-CoV-2 in challenge studies and reported natural infection rates approaching 40% in free-ranging WTD in the U.S. Thus, understanding the infection and transmission dynamics of SARS-CoV-2 in WTD is critical to prevent future zoonotic transmission to humans and for implementation of effective disease control measures. Here, we demonstrated that following intranasal inoculation with SARS-CoV-2, WTD fawns shed infectious virus up to day 5 post-inoculation (pi), with high viral loads shed in nasal and oral secretions. This resulted in efficient deer-to-deer transmission on day 3 pi. Consistent a with lack of infectious SARS-CoV-2 shedding after day 5 pi, no transmission was observed to contact animals added on days 6 and 9 pi. We have also investigated the tropism and sites of SARS-CoV-2 replication in adult WTD. Infectious virus was recovered from respiratory-, lymphoid-, and central nervous system tissues, indicating broad tissue tropism and multiple sites of virus replication. The study provides important insights on the infection and transmission dynamics of SARS-CoV-2 in WTD, a wild animal species that is highly susceptible to infection and with the potential to become a reservoir for the virus in the field. Author summaryThe high susceptibility of white-tailed deer (WTD) to SARS-CoV-2, their ability to transmit the virus to other deer, and the recent findings suggesting widespread SARS-CoV-2 infection in wild WTD populations in the U.S. underscore the need for a better understanding of the infection and transmission dynamics of SARS-CoV-2 in this potential reservoir species. Here we investigated the transmission dynamics of SARS-CoV-2 over time and defined the major sites of virus replication during the acute phase of infection. Additionally, we assessed the evolution of the virus as it replicated and transmitted between animals. The work provides important information on the infection dynamics of SARS-CoV-2 in WTD, an animal species that - if confirmed as a new reservoir of infection - may provide many opportunities for exposure and potential zoonotic transmission of the virus back to humans.

microbiology↗