Evidence of Exposure to Sars-Cov-2 and Various Neutralizing Antibody Profiles Against Variants of Concerns in Cats and Dogs, Luxembourg

Abstract

Background and aims of the study: Besides highly susceptible farmed minks, the highest number of independent SARS-CoV-2 spillovers is reported in cats and dogs. In addition, some virus variants acquired mutations altering host tropism. We thus assessed the prevalence of SARS-CoV-2 infections in pets in Luxembourg and aimed at identifying the factors promoting inter-species transmission to assist authorities in their containment efforts in light of SARS-CoV-2 evolution and variant replacements. 

Methods and Results: A total of 220 cats and 264 dogs were recruited between October 2020 and April 2021 coinciding with the 3rd (driven by B.1 strains) and 4th (Alpha B.1.1.7 and Beta B.1.351) SARS-CoV-2 waves. Among those, 24.4% of animals were recruited in households with history of SARS-CoV-2 in humans. Variants B.1.221, B.1.177, B.1 as well as Beta B.1.351 were identified in the only 4/711 RT-qPCR positive swabs, corresponding to the variants concomitantly circulating in the human population. Prevalence of neutralizing antibodies (NAbs) reached 28.2% (cats: 25.5%; dogs: 30.4%) in SARS-CoV-2 affected households. In these households, we did not identify any factors contributing to an increased risk of transmission, likely due to already intensive contacts. 

In a second cohort of diagnostic leftover sera (April 2020-March 2022), 4.2% (39/918) of cats and 3.0% (47/1572) of dogs had NAbs. The use of a multiplexed surrogate neutralization assay harbouring recombinant spike proteins from various variants also highlighted different humoral response profiles. The majority of animal sera had the highest NAb titers against the ancestral B.1 strain (55%), followed by Delta B.1.617.2 (16%), Alpha B.1.1.7 (14%), Omicron B.1.1.529-BA.1 (6%) and Gamma P.1 (4%). Rolling 3-months seroprevalence rates tended to increase over time, likely resulting from increasing opportunities for exposure to the virus and/or lasting presence of NAbs after infection. 

Implications: Seroprevalence rates were not consistent with increasing transmission rates of recent variants of concerns to companion animals or sustained animal-to-animal transmission. This study nevertheless highlighted the high frequency of cross-species transmission events in SARS-CoV-2 affected households, regardless of the variants at play. Clear recommendations to affected owners for minimizing transmission to domestic animals are thus warranted.

Note: This conference abstract was presented at the 9th International Conference on Infectious Disease Dynamics organized by the journal Epidemics. This abstract has not been screened by SSRN for potential for public harm and should not be used to inform any clinical decision making. No competing interests or funding statements have been declared.