CEEZAD researchers advance understanding of SARS-CoV-2 detection in domestic cats

An article co-authored by the Director of the Center of Excellence for Emerging and Zoonotic Animal Diseases (www.ceezad.org) and the Center on Emerging and Zoonotic Infectious Diseases (CEZID; https://www.k-state.edu/cezid/) reports on advancements in detection of SARS-CoV-2 antibodies in domestic cats.

The article was co-authored by Dr. Juergen A. Richt, Regents and University Distinguished Professor at Kansas State University and director of CEEZAD and CEZID. It was published in the April 2025 edition of the Journal of Virological Methods. Other co-authors include Natasha Gaudreault, Konner Cool, Dasheveg Bold, and Bailey Roberts, all of the Department of Diagnostic Medicine and Pathology at Kansas State University and CEEZAD, and Drs. Keyla Lopez and Roman Pogranichniy at the Veterinary Diagnostic Laboratory of the College of Veterinary Medicine at Kansas State University.

The emergence of SARS-CoV-2 raised concerns about the potential for interspecies transmission, particularly among domestic animals. CEEZAD researchers evaluated the seroprevalence of SARS-CoV-2 antibodies in domestic cats from various sites in North America. A total of 216 serum samples collected between December 2019 and February 2022, were analyzed using four different enzyme-linked immunosorbent assays (ELISAs), including a commercial surrogate virus neutralization test (sVNT), a commercial double antigen test (dN ELISA), and two in-house developed indirect ELISAs based on the receptor-binding domain (RBD iELISA) and the nucleocapsid (N iELISA) protein, respectively.

Seropositive samples in the commercial ELISAs were subjected to classical virus neutralization test (cVNT) employing the Wuhan-like USA-WA1/2020 SARS-CoV-2 isolate. The findings revealed that 6% (12/216) of the cat serum samples tested positive by the sVNT, while 4% (9/216) tested positive for the dN-ELISA. The N iELISA showed a higher seroprevalence, with 31% of the samples testing positive, possibly due to cross-reactive antibodies against the N protein of other coronavirus commonly found in cats.

There was a high concordance between sVNT, cVNT, and the RBD iELISA. Among positive sVNT cat serum samples, 75% (9/12) exhibited neutralizing titers using the cVNT test, with all samples also being positive by the RBD iELISA. Notably, the RBD iELISA and sVNT demonstrated high sensitivity and specificity in detecting SARS-CoV-2 antibodies (100 and 79% for iRBD; 100 and 90% for sVNT).

The study provides important insights into the seroprevalence of SARS-CoV-2 antibodies in domestic cats, highlighting the potential for interspecies transmission and the need for continued monitoring of SARS-CoV-2 in animal populations.

Detection of SARS-CoV-2- specific antibodies in domestic cats using different ELISA tests - PubMed