Preliminary Study on the Efficacy of a Recombinant, Subunit SARS-CoV-2 Animal Vaccine against Virulent SARS-CoV-2 Challenge in Cats

Abstract

The objective of this work was to evaluate the safety and efficacy of a recombinant, subunit SARS-CoV-2 animal vaccine in cats against virulent SARS-CoV-2 challenge. Two groups of cats were immunized with two doses of either a recombinant SARS-CoV-2 spike protein vaccine or a placebo, administered three weeks apart. Seven weeks after the second vaccination, both groups of cats were challenged with SARS-CoV-2 via the intranasal and oral routes simultaneously. Animals were monitored for 14 days post-infection for clinical signs and viral shedding before being humanely euthanized and evaluated for macroscopic and microscopic lesions. The recombinant SARS-CoV-2 spike protein subunit vaccine induced strong serologic responses post-vaccination and significantly increased neutralizing antibody responses post-challenge. A significant difference in nasal and oral viral shedding, with significantly reduced virus load (detected using RT-qPCR) was observed in vaccinates compared to mock-vaccinated controls. Duration of nasal, oral, and rectal viral shedding was also significantly reduced in vaccinates compared to controls. No differences in histopathological lesion scores were noted between the two groups. Our findings support the safety and efficacy of the recombinant spike protein-based SARS-CoV-2 vaccine which induced high levels of neutralizing antibodies and reduced nasal, oral, and rectal viral shedding, indicating that this vaccine will be efficacious as a COVID-19 vaccine for domestic cats.

SARS-CoV-2 morbidity, treatment interventions, and vaccination practices in tigers (Panthera tigris ssp) in North American zoos

“…Additionally, a challenge study performed in domestic cats documented a strong anamnestic response and reduced viral load and shedding in vaccinated cats compared to controls challenged with intranasal and oral SARS-CoV-2, supporting its efficacy. 36 Preliminary research investigating the Zoetis SARS-CoV-2 recombinant vaccine in several nondomestic felids, including tigers, found initial antibody response and increasing titers in most animals 3 months after vaccination, with titers decreasing at 6 months after vaccination. 37 Despite this limited evidence of initial antibody response in tigers, in the present study, 9 tigers that tested positive for SARS-CoV-2 (and developed clinical signs) had received a full 2-dose course of the vaccine prior to infection.…”