Development and validation of a multiplex bead based assay for the detection of antibodies directed against SARS-CoV-2 proteins

Transplant recipients who develop COVID-19 may be at increased risk for morbidity and mortality. Determining antibody status against SARS-CoV-2 in candidates and recipients will be important to understand the epidemiology and clinical course of COVID-19 infection in this population. There are multiple antibody tests to detect antibodies to SARS-CoV-2, but their performance varies according to their platforms and the antigenic targets, making interpretation of the results challenging. Additionally, currently available serological tests do not exclude the possibility that positive responses are due to cross reactive antibodies to community coronaviruses. This study describes the development and validation of a high throughput multiplex bead based antibody detection assay with the capacity to identify, simultaneously, patient responses to five distinct SARS-CoV-2 proteins. The antibody response to these proteins are SARS-CoV-2 specific as antibodies against four community coronaviruses do not cross-react. Assay configuration is essentially identical to the single antigen bead assays used in the majority of histocompatibility laboratories around the world and could easily be implemented into routine screening of transplant candidates and recipients. This new assay provides a novel tool to interrogate the spectrum of immune responses to SAR-CoV-2 and is uniquely suitable for use in the transplant setting.