Development of a COVID-19 Multiplex for Serological Screening of Nonhuman Primate Colonies

In the fall of 2019, a novel beta coronavirus was detected in humans in Wuhan, China The infection spread globally causing a pandemic in the human population This novel virus is most closely related to severe acute respiratory syndrome (SARS-CoV aka SARS-CoV1), which spread globally in 2002-2004, and has been formally named as SARS-CoV2 or more commonly referred to as COVID19 A new high throughput COVID-Plex serology assay has been developed that utilizes 6-antigen coupled beads, 2 specific for detecting SARSCoV2 antibodies and 1 antigen for each of the 4 human seasonal coronavirus strains (229E, NL63, HKU1 and OC43) Recombinant SARS-CoV2 proteins for the full length spike (S1 + S2 subunits) and nucleoprotein (NP) as well as full length spike proteins for 229E, NL63, HKU1 and OC43 were coupled to Luminex magnetic beads Samples were interpreted as COVID19 antibody positive if both SARS-CoV2 beads (spike and NP) scored above the assay cutoffs Sensitivity of the COVID-Plex assay was assessed by using 50 positive human sera with 47/50 scoring positive for COVID antibodies Three negative samples either scored only on the alpha coronavirus seasonal strain beads or completely negative on all 6 coupled beads (COVID as well as the 4 seasonal spike protein coupled beads) These samples were also confirmed negative by a commercial COVID19 spike protein ELISA Specificity of the assay was tested by screening pre-2019 human and macaque samples with 0/8 and 0/24 positive samples, respectively Recently collected sera in 2020 from rhesus and cynomolgus macaque colonies (n=322) representing several different institutions resulted in only one positive finding resulting in 99 7% assay specificity These studies confirm that COVID-Plex, a blood based test using serum/plasma is sensitive and specific for screening of COVID19 (SARS-CoV2) antibodies in NHPs Also the COVID-Plex can be performed in a user-friendly and high throughput format while screening for other infectious SPF agents using the same sample