Development of a rapid SARS-CoV-2 neutralisation test by detecting antibodies that block interaction of spike protein receptor-binding domain (RBD) with angiotensin-converting enzyme 2 (ACE2)

The urgent need for a rapid and reliable Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) neutralising antibody detection test compatible with routine clinical laboratory testing currently exists. This is necessary to provide accurate estimates of immunity and to monitor vaccine effectiveness. Utilising Biochip Array Technology (BAT), the Randox SARS-CoV-2 Biochip proxy virus neutralisation test (pVNT) has been developed. Immobilising SARS-CoV-2 Spike RBD on the Biochip surface, innovative assay design enables direct sample addition to the Biochip well without the need for off-board sample pre-incubation step. Results are reported within 1.5 hours and testing is carried out without the prerequisite of live virus or biosafety level 3 (BSL3) laboratory facilities. In this study, assay validation is performed using recombinant antibodies and clinical samples and an excellent correlation against conventional virus neutralisation methods is established (100% clinical specificity and 98% clinical sensitivity). Serial dilution of samples with high neutralising antibody levels demonstrate end-point sample dilutions comparable with those obtained using the SARS-CoV-2 microneutralisation test. Species independent neutralising antibody detection capacity of the SARS-CoV-2 Biochip pVNT is also demonstrated. The findings of this study exemplify the utility of the SARS-CoV-2 Biochip pVNT as a robust and reliable method for the accurate measurement of neutralising antibodies against SARS-CoV-2 and the availability of this test can now positively impact current testing deficiencies in this area.