Results
Development of a robust ELISA for SARS-CoV-2 antibodies in cats, dogs and camels.
Titrating the crude lysate
The crude lysate used to coat the ELISA plates was titrated in the range of 5x10-2 and 5x10-10 of the viral lysate of 80% CPE viral harvest. Wells without coating (No coats) were included and a positive serum (C0874) was used to check if the serum is binding on anything other than the antigen. First pre-COVID-19 and post COVID-19 camel sera were screened using a commercial kit to identify reacting samples. The positively reacting camel sera was selected and used at a dilution of 1/1000, cat & dogs sera was used at 1/50. Wells with antigen coating but no sera (No Sera) were included to check for nonspecific cross-reactions.
The crude lysate antigen reactivity with camel, cats and dogs sera was optimal at a dilution range of 5x10-7 and 5x10-8 of the lysate of 80% CPE viral harvest. Beyond 5x10-8 dilution, the lysate couldn’t pick or distinguish between a SARS CoV-2 negative from a positive sera (Fig.2).