A multiplex serological assay for the characterization of IgG immune response to SARS-CoV-2

Abstract

In the fight against SARS-COV-2, the development of serological assays based on different antigenic domains represent a versatile tool to get a comprehensive picture of the immune response or differentiate infection from vaccination beyond simple diagnosis. Here we use a combination of the Nucleoprotein (NP), the Spike 1 (S1) and Spike 2 (S2) subunits, and the receptor binding domain (RBD) and N-terminal domain (NTD) of the Spike antigens from the CoViDiag® multiplex IgG assay, to follow the immune response to SARS-CoV-2 infection over a long time period and depending on disease severity. Using a panel of 209 sera collected from 61 patients up to eight months after infection, we observed that most patients develop an immune response against multiple viral epitope, but anti-S2 antibodies seemed to last longer. For all the tested IgGs, we have found higher responses for hospitalized patients than for non-hospitalized ones. Moreover the combination of the five different IgG responses increased the correlation to the neutralizing antibody titers than if considered individually. Multiplex immunoassays have the potential to improve diagnostic performances, especially for ancient infection or mild form of the disease presenting weaker antibody responses. Also the combined detection of anti-NP and anti-Spike-derived domains can be useful to differentiate vaccination from viral infection and accurately assess the antibody potential to neutralize the virus.

Kinetics of the SARS-CoV-2 Antibody Avidity Response Following Infection and Vaccination

“…In contrast to monoplex assays such as ELISA, multiplex serological assays can simultaneously measure antibodies to multiple antigens, allowing for more epidemiological information to be obtained from a single test. It has been demonstrated that multiplex assays can have higher accuracy than monoplex assays [ 11 , 12 ]; can distinguish vaccinated from naturally infected individuals [ 13 ]; can provide estimates of the time since previous infection [ 3 ]; and can simultaneously measure immunity to seasonal coronaviruses [ 14 ].…”

Simultaneous measurement of the antibody responses against SARS-CoV-2 and its multiple variants by a phage display mediated immuno-multiplex quantitative PCR-based assay

“…For example, the research of Grossberg et al ( Grossberg et al, 2021 ) showed that the antibody levels of S1-RBD IgA, NP IgG, and S2 IgA can be used to identify severe, mild, and asymptomatic groups of COVID-19 patients. Considering increasing vaccination rates, combined detection of anti-NP and anti-Spike antibodies can also be used to differentiate the immune response from viral infection and accurately assess immunity ( Brochot et al, 2022 ). Compared with flow cytometry, the assay based on Pi-mqPCR can be combined with nucleic acid amplification tests and is more suitable for clinical serological diagnosis.…”