Analysis of Serologic Cross-Reactivity Between Common Human Coronaviruses and SARS-CoV-2 Using Coronavirus Antigen Microarray

Abstract

The current practice for diagnosis of SARS-CoV-2 infection relies on PCR testing of nasopharyngeal or respiratory specimens in a symptomatic patient at high epidemiologic risk. This testing strategy likely underestimates the true prevalence of infection, creating the need for serologic methods to detect infections missed by the limited testing to date. Here, we describe the development of a coronavirus antigen microarray containing immunologically significant antigens from SARS-CoV-2, in addition to SARS-CoV, MERS-CoV, common human coronavirus strains, and other common respiratory viruses. A preliminary study of human sera collected prior to the SARS-CoV-2 pandemic demonstrates overall high IgG reactivity to common human coronaviruses and low IgG reactivity to epidemic coronaviruses including SARS-CoV-2, with some cross-reactivity of conserved antigenic domains including S2 domain of spike protein and nucleocapsid protein. This array can be used to answer outstanding questions regarding SARS-CoV-2 infection, including whether baseline serology for other coronaviruses impacts disease course, how the antibody response to infection develops over time, and what antigens would be optimal for vaccine development.

Protocol and Reagents for Pseudotyping Lentiviral Particles with SARS-CoV-2 Spike Protein for Neutralization Assays

“…Infection with SARS-CoV-2 elicits antibodies that bind to the virus [1][2][3][4][5][6]. However, as is the case for all viruses [7][8][9][10], only some of these antibodies neutralize the virus's ability to enter cells [4,5,11,12].…”

Protocol and reagents for pseudotyping lentiviral particles with SARS-CoV-2 Spike protein for neutralization assays

“…Infection with SARS-CoV-2 elicits antibodies that bind to the virus [1][2][3][4][5][6]. But as is the case for all viruses [7][8][9][10], only some of these antibodies neutralize the virus's ability to enter cells [4,5,11,12].…”

“…But while there are now well-characterized and high-throughput methods (such as ELISA assays) to measure total antibody binding to SARS-CoV-2 or some of its key constituent proteins [2,6,26], quantifying neutralizing antibody activity is more difficult. The most biologically relevant method is to directly measure how antibodies or sera inhibit infection of cells by replicationcompetent SARS-CoV-2.…”

A serological assay to detect SARS-CoV-2 seroconversion in humans

“…Similar findings were reported in a recent study where sera from negative control subjects reacted well with spike proteins from human coronavirus but not with SARS-CoV-2 (ref. 15 ). This is notable because it suggests that humans are serologically naive to SARS-CoV-2, which may explain the relatively high basic reproduction number (or R0) of SARS-CoV-2 compared with that of other respiratory viruses, such as influenza virus 16 .…”