In this study, researchers found that multiplex COVID-19 Immunoblot (IB) assays offer many advantages for evaluating antibody responses to multiple SARS-CoV-2 proteins in a single sample in COVID-19 patients.
The authors found that IB assay results can be obtained in less than 3 hours after serum or plasma collection using pre-prepared IB membrane strips and require minimal washing and reagent addition steps. The IB assays also maintain visible signals that remain stable for several weeks and are easy to interpret. The IB assay can also be adapted to detect antibodies of other immunoglobulin classes, and in other bodily fluids such as saliva and tears, which is important because the mucosal IgA and blood IgG and IgM antibody responses in COVID-19 can differ significantly. The COVID-19 IB assay is also easily expanded to include additional virus antigens.
Results of the study confirmed other common observations in COVID-19 in regard to IgM and IgG antibody levels being variable with time after infection. Additional findings of the study suggest that determining both IgG and IgM antibodies early in an infection, before approximately 10 days from onset of disease, and IgG antibodies later (at about 8 weeks after infection), provide the best sensitivity for detecting antibody responses in COVID-19 IBs.
The clinical sensitivity and specificity of the COVID-19 IB assays meet the United States recommendations for laboratory serological diagnostic tests however, authors noted may be most useful for large seroepidemiological studies in specific populations with a high prevalence of COVID-19.
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