Removing Negative Impacts from Inevitable Nonreproducible and Nonspecific Antibody-Probe Interactions in Viral Serology.

Serological assays are indispensable tools in public health. Presently deployed serological assays, however, largely overlook research progress made in the last two decades that jeopardizes the conceptual foundation of these assays, i.e., antibody (Ab) specificity. Challenges to traditional understanding of Ab specificity include Ab polyspecificity and most recently nonreproducible Ab-probe interactions (NRIs). Here, using SARS-CoV-2 and four common livestock viruses as a test bed, we developed a new serological platform that integrates recent understanding about Ab specificity. We first demonstrate that the response rate (RR) from a large-sized serum pool (∼100) is not affected by NRIs or by nonspecific Ab-probe interactions (NSIs), so RR can be incorporated into the diagnostic probe selection process. We subsequently used multiple probes (configured as a "protein peptide hybrid microarray", PPHM) to generate a digital microarray index (DMI) and finally demonstrated that DMI-based analysis yields an extremely robust probabilistic trend that enables accurate diagnosis of viral infection that overcomes multiple negative impacts exerted by NSI/NRI. Thus, our study with SARS-CoV-2 confirms that the PPHM-RR-DMI platform enables very rapid development of serological assays that outperform traditional assays (for both sensitivity and specificity) and supports that the platform is extendable to other viruses.