Susceptibility of swine cells and domestic pigs to SARS-CoV-2

ABSTRACT

The emergence of SARS-CoV-2 has resulted in an ongoing global pandemic with significant morbidity, mortality, and economic consequences. The susceptibility of different animal species to SARS-CoV-2 is of concern due to the potential for interspecies transmission, and the requirement for pre-clinical animal models to develop effective countermeasures. In the current study, we determined the ability of SARS-CoV-2 to (i) replicate in porcine cell lines, (ii) establish infection in domestic pigs via experimental oral/intranasal/intratracheal inoculation, and (iii) transmit to co-housed naïve sentinel pigs. SARS-CoV-2 was able to replicate in two different porcine cell lines with cytopathic effects. Interestingly, none of the SARS-CoV-2-inoculated pigs showed evidence of clinical signs, viral replication or SARS-CoV-2-specific antibody responses. Moreover, none of the sentinel pigs displayed markers of SARS-CoV-2 infection. These data indicate that although different porcine cell lines are permissive to SARS-CoV-2, five-week old pigs are not susceptible to infection via oral/intranasal/intratracheal challenge. Pigs are therefore unlikely to be significant carriers of SARS-CoV-2 and are not a suitable pre-clinical animal model to study SARS-CoV-2 pathogenesis or efficacy of respective vaccines or therapeutics.

KEYWORDS:

• SARS-CoV-2
• COVID-19
• swine
• coronavirus
• pigs
• infection models
• zoonotic disease

Acknowledgements

We gratefully thank the staff of KSU Biosecurity Research Institute, the histological laboratory at the Kansas State Veterinary Diagnostic Laboratory (KSVDL), the CMG staff and Gleyder Roman-Sosa, Yonghai Li, Konner Cool, Emily Gilbert-Esparza, and Chester McDowell at KSU. We also gratefully acknowledge the members of the Histology and Immunohistochemistry section at the Louisiana Animal Disease Diagnostic Laboratory (LADDL) for their assistance on slide preparation and staining. The following reagent was obtained through BEI Resources, National Institute of Allergy and Infectious Diseases (NIAID), National Institutes of Health (NIH): SARS-CoV-2 Virus strain USA-WA1/2020 (catalogue # NR-52281).

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

Funding for this study was provided through grants from the National Bio and Agro-Defense Facility (NBAF) Transition Funds from the State of Kansas. Kansas State University internal funds, the NIAID Centers of Excellence for Influenza Research and Surveillance under contract number HHSN 272201400006C, and the Department of Homeland Security Center of Excellence for Emerging and Zoonotic Animal Diseases [grant number HSHQDC-16-A-B0006] to J.A.R. H.R. is funded through the Intramural Research Program, NIAID, NIH.