2.5 Serology
Serum samples were being collected at specific time-points from all cats
for detection of SARS-CoV-2-specific antibodies (Figure 1). For this
reason, the cats were mildly sedated with the alpha-2 adrenoceptor
agonist dexmedetomidine (10 μg/kg, im). Approximately 40 minutes after
administration and once the procedures were completed, sedation was
rapidly reversed by the administration of the specific alpha-2
adrenoceptor antagonist, atipamezol (100 μg/kg, im).
The commercially available ID Screen® SARS-CoV-2 Double Antigen
Multi-species ELISA (ID.vet, Montpellier, France) kit was used. The
antigen in this immunological assay is the N protein of SARS-CoV-2, and
its format enables the detection of SARS-CoV-2-specific antibodies in
the tested sera, irrespective of their isotype. Testing was performed
following the manufacturer’s instructions. Optical density (OD) values
were recorded using a Stat Fax 3200 microplate photometer (Awareness
Technology Inc., Palm City, FL, USA). For each sample, S/P% percentages
were calculated as follows:
(ODSample-ODNegative
Control)/(ODPositive Control-ODNegative
Control) × 100, with serum samples presenting S/P% ≥ 60% being
considered as positive.
Additionally, anticoagulated blood samples from all cats obtained on D16
were tested for Feline immunodeficiency virus (FIV)-specific
antibodies and Feline leukemia virus (FeLV) antigens, using a
rapid enzyme immunoassay test (SNAP® FIV/FeLV Combo Test; IDEXX
Laboratories Inc., Westbrook, ME, USA).