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URL: https://pubmed.ncbi.nlm.nih.gov/41150425/

⇱ SARS-COV-2 Vaccination Response in Non-Domestic Species Housed at the Toronto Zoo - PubMed

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Abstract

Background: Due to the wide host range of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), vaccination has been recommended for susceptible species in zoological collections, particularly to protect endangered species. The Zoetis® Experimental Mink Coronavirus Vaccine (Subunit) was temporarily authorized in 2021-2024 for emergency use in North America for this purpose. However, there are limited data regarding its safety or efficacy in non-domestic mammals. The present study was conducted to assess the ability of this vaccine to elicit serum neutralizing titers against SARS-CoV-2 in selected animals from the Toronto Zoo (TZ) vaccinated during 2022. Methods: Serum samples were collected from 24 individuals across four families (Cervidae, Felidae, Ursidae, and Hyaenidae) and tested using a surrogate virus neutralization test (sVNT) and a plaque-reduction neutralization test (PRNT). Results: The results showed that all species developed some neutralizing titers after at least one vaccine dose, except for polar bears, which showed no seroconversion. Felids and hyenas had the highest neutralizing titers, which peaked at 3 and declined between 4 and 6 months after boost. These differences may stem from species-specific immune responses or lack of vaccination protocols tailored to individual species. Conclusions: While natural infection with SARS-CoV-2 could not be ruled out in the cohort of this study, insights from our results have the potential to inform future vaccine recommendations for non-domestic species. Furthermore, our study highlighted the value of competitive assays in assessing serological responses across a broad range of exotic species, for which reagents, such as anti-isotype antibodies, are often unavailable.

Keywords: Zoetis; plaque-reduction test; polar bears; subunit vaccine; surrogate neutralization; zoo.

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Conflict of interest statement

The authors declare no conflicts of interest.

Figures

👁 Figure 1
Figure 1
Percentage of surrogate virus neutralization in sera from animals vaccinated at the Toronto Zoo with the Zoetis® Experimental Mink Coronavirus Vaccine (Subunit). All the single-animal data in the cohort are grouped at the species level, including replicates within the same timepoint. Timepoints are defined as time intervals relative to the prime and booster doses (arrowheads). Represented are either single values, or median with range, when multiple values were available for each timepoint. Dotted line is placed at 30% of inhibition, the neutralization threshold according to the Genscript® kit.
👁 Figure 2
Figure 2
Plaque-reduction neutralization test 70% (PRNT70) against the ancestral SARS-CoV-2 strain, in the sera of animals vaccinated at the Toronto Zoo with the Zoetis® Experimental Mink Coronavirus Vaccine (Subunit). For each animal, paired pre-vaccination and post-vaccination sera were tested. Represented are single values, expressed as log2 of reciprocal PRNT70 titer. Lack of neutralizing titer (i.e., lack of neutralization at no serum dilution) is depicted by placeholders on the x axis (i.e., negative).

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