Guest edited collection serological study of SARS-CoV-2 antibodies in japanese cats using protein-A/G-based ELISA

Abstract

Background Little is known about the epidemic status of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in cats in Japan due to insufficiently reliable seroepidemiological analysis methods that are easy to use in cats. Results We developed a protein-A/G-based enzyme-linked immunosorbent assay (ELISA) to detect antibodies against SARS-CoV-2 in cats. The assay was standardized using positive rabbit antibodies against SARS-CoV-2. The ELISA results were consistent with those of a conventional anti-feline-immunoglobulin-G (IgG)-based ELISA. To test the protein-A/G-based ELISA, we collected blood samples from 1,969 cats that had been taken to veterinary clinics in Japan from June to July 2020 and determined the presence of anti-SARS-CoV-2 antibodies. Nine cats were found to have SARS-CoV-2 S1-specific IgG, of which 4 had recombinant receptor-binding domain-specific IgG. Of those 9 samples, one showed neutralizing activity. Based on these findings, we estimated that the prevalence of SARS-CoV-2 neutralizing antibodies in cats in Japan was 0.05% (1/1,969 samples). This prevalence was consistent with the prevalence of neutralizing antibodies against SARS-CoV-2 in humans in Japan according to research conducted at that time. Conclusions Protein-A/G-based ELISA has the potential to be a standardized method for measuring anti-SARS-CoV-2 antibodies in cats. The infection status of SARS-CoV-2 in cats in Japan might be linked to that in humans.

Seroprevalence of SARS-CoV-2 antibodies in dogs and cats during the early and mid-pandemic periods in Japan

“…Our findings revealed that two dogs (2/488, 0.41%) in 2020, one cat (1/355, 0.28%) in 2020, four cats (4/251, 1.6%) in 2021 were positive for anti-SARS-CoV-2 antibodies. In Japan, two previous studies have reported seroprevalence in dogs and cats: in dogs, 3 of 494 (0.61%) serum samples that were collected in 2020 were positive by ELISA [ 29 ]; and in cats, 9 of 1969 (0.48%) serum samples that were collected in 2020 were positive by ELISA [ 30 ]. In other countries and regions, seroprevalence of SARS-CoV-2 antibodies in dogs and cats by use of ELISAs or neutralization assays was reported to range from 0.01 to 16.0% and 0–18.9%, respectively [ [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] , [21] , [22] , [23] , [24] , [25] ].…”

“…Of these three ELISA-positive samples, one possessed neutralizing antibodies against SARS-CoV-2. In cats, 9 of 1969 (0.48%) blood samples that were collected between June 2020 and July 2020 were positive by ELISA for the detection of antibodies against the S1 protein of SARS-CoV-2 [ 30 ]. Of these 9 ELISA-positive samples, one showed neutralizing activity against SARS-CoV-2.…”