DEVELOPMENT OF LABORATORY AND POINT OF CARE DETECTION PLATFORMS FOR COVID-19 NEUTRALIZING ANTIBODIES AND IMMUNE STATUS

INTRO: Neutralizing antibody responses, including the omicron and other variants targeting SARS-CoV-2, are important serological parameter that may predict protective immunity for COVI-19. This protection status may have a direct impact on the response to this virus including vaccination and protection strategies. METHODS: The ImTracker Assay™ developed by the National University of Singapore and Gen-Y Biologics is designed to detect and quantify the inhibition of Spike-RBD binding to ACE-2 as a surrogate for SARS-CoV-2 VOC neutralization. Human antibodies that bind to neutralization determinants on Spike-RBDs will block or occlude binding of these viral proteins to the human host receptor, ACE-2. The binding activity of ACE-2 to Spike-RBD in a test sample is compared with negative control sera (minus neutralizing antibodies) where unrestricted binding between the two receptors is not inhibited and a QC reagent (positive control) where binding between Spike-RBD to ACE-2 is inhibited by a defined VOC crossneutralizing agent. A Lateral Flow Immunoassay (LFI), using saliva as a sample, has been developed to detect both mucosal IgG and IgA antibodies. The assays utilized RBD and Nucleocapsid antigens. FINDINGS: The assay has been evaluated against all variants including Omicron B.1.1.529 and BA.2 and more recently BA.4 and BA.5. The Assay successfully evaluated over 3,800 positive and 1,300 negative samples utilizing the pseudovirus neutralization test (PVNT) as a reference assay, calibrating this with the WHO international standard for anti-SARS-CoV-2 immunoglobulin. CONCLUSION: ImTracker Assay™ had an overall Sensitivity of 100% and a specificity >96% when benchmarked against a standard PVNT assay. The assay can add additional new variants in less than 45 days. The LFI Immune status provided correlation to vaccination status and when compared to a standard ELISA assay and PVNT neutralizaton assay,provided comparable results.