Neutralizing antibodies against the SARS-CoV-2 ancestral strain and Omicron BA.1 subvariant in dogs and cats in Mexico

The virus SARS-CoV-2 originated in Wuhan, China, in 2019 and has since spread worldwide, infecting humans and animals. Several reports have described the seroprevalence of antibodies in dogs and cats, but there are no reports from Mexico. This study aimed to evaluate the seroprevalence of neutralizing antibodies against the ancestral strain and Omicron BA.1 subvariant in dogs and cats in Mexico. A total of 1111 samples from dogs (n=1052) and cats (n=59) were collected in different regions of Mexico, and the presence of neutralizing antibodies (nAbs) was evaluated by a plaque reduction neutralization test (PRNT90) and microneutralization (MN). The results showed that 15.25% (9 of 59) of cats and 2.85% (30 of 1052) of dogs presented nAbs against the ancestral strain of SARS-CoV-2. However, the analysis of nAbs against Omicron BA.1 in cats showed the same percentage of positive animals but a reduction in the titer. In the case of dogs, 2.09% (22 of 1052) showed nAbs against Omicron BA.1. These results agree with previous reports showing that antibodies are more frequent in cats than in dogs and that these antibodies have a lower capacity to neutralize Omicron BA.1