Experimental re-infected cats do not transmit SARS-CoV-2

Authors: GAUDREAULT, NATASHA - Kansas State University; MOROZOV, IGOR - Kansas State University; TRUJILLO, JESSIE - Kansas State University; MEEKINS, DAVID - Kansas State University; CAROSSINO, MARIANO - Louisiana State University; MADDEN, DANIEL - Kansas State University; COOL, KONNER - Kansas State University; LIBANORI-ARTIAGA, BIANCA - Kansas State University; MCDOWELL, CHESTER - Kansas State University; BOLD, DASHZEVEG - Kansas State University; MA, WENJUN - University Of Missouri; HENNINGSON, JAMIE - Kansas State University; BALASURIYA, UDENI - Louisiana State University; Wilson, William; GARCIA-SASTRE, ADOFO - The Icahn School Of Medicine At Mount Sinai; RICHT, JUERGEN - Kansas State University

Submitted to: Emerging Microbes & Infections
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2021
Publication Date: 4/2/2021
Citation: Gaudreault, N.N., Morozov, I., Trujillo, J.D., Meekins, D.A., Carossino, M., Madden, D.W., Cool, K., Libanori-Artiaga, B., McDowell, C., Bold, D., Ma, W., Henningson, J., Balasuriya, U.B., Wilson, W.C., Garcia-Sastre, A., Richt, J.A. 2021. Experimental re-infected cats do not transmit SARS-CoV-2. Emerging Microbes & Infections. 10(1):638-650. https://doi.org/10.1080/22221751.2021.1902753.
DOI: https://doi.org/10.1080/22221751.2021.1902753

Interpretive Summary: The global pandemic Coronavirus Disease 2019 (COVID-19) is caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The susceptibility of domestic cats to SARS-CoV-2 has been demonstrated previously and can efficiently transmit the virus to naïve cats. In this study, we address whether cats previously exposed to SARS-CoV-2 can be re-infected with SARS-CoV-2 twenty-one days post- primary challenge (DPC). Our results indicate that cats previously infected with SARS-CoV-2 can be experimentally re-infected with SARS-CoV-2; however, the levels of virus shed from the nasal, oral and rectal cavities of the re-challenged cats was insufficient for transmission to co-housed naïve sentinels. We conclude that SARS-CoV-2 infection in cats induces immune responses that provide partial non-sterilizing immune protection against reinfection, and therefore, immunological approaches to prevent and potentially treat SARS-CoV-2 are possible.

Technical Abstract: Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) is the causative agent of Coronavirus Disease 2019 (COVID-19) and responsible for the current global pandemic. We and others have previously demonstrated that domestic cats are susceptible to SARS-CoV-2 infection and can efficiently transmit the virus to naïve cats. In this study, we address whether cats previously exposed to SARS-CoV-2 can be re-infected with SARS-CoV-2 twenty-one days post- primary challenge (DPC). In two independent studies, three or five primary SARS-CoV-2-infected cats were re-challenged with SARS-CoV-2 at 21 DPC/0 days post-secondary challenge (DP2C) and necropsied at 4, 7 and 14 DP2C. In the second re-infection study, two naïve sentinels were co-mingled with the re-challenged cats at 1 DP2C. Daily temperatures and clinical scores were recorded, and nasal, oropharyngeal, and rectal swabs, blood, and serum were collected and evaluated. Viral RNA was transiently shed via the nasal, oropharyngeal and rectal cavities of the re-challenged cats. Viral RNA was detected in various tissues of re-challenged cats euthanized at 4 DP2C, mainly in the upper respiratory tract and lymphoid tissues, but less frequently and at lower levels in the lower respiratory tract when compared to primary SARS-CoV-2 challenged cats at 4 DPC. An anamnestic neutralizing antibody response was observed in the re-infected animals at 7 and 11 DP2C. Importantly, naïve sentinels co-housed with re-challenged cats for 13 days did not shed virus or seroconverted. Together, our results indicate that cats previously infected with SARS-CoV-2 can be experimentally re-infected with SARS-CoV-2; however, the levels of virus shed from the nasal, oral and rectal cavities of the re-challenged cats was insufficient for transmission to co-housed naïve sentinels. We conclude that SARS-CoV-2 infection in cats induces immune responses that provide partial non-sterilizing immune protection against reinfection, and therefore, immunological approaches to prevent and potentially treat SARS-CoV-2 are possible.