Rathe JA, Hemann EA, Eggenberger J, Li Z, Knoll ML, Stokes C, Hsiang TY, Netland J, Takehara KK, Pepper M, Gale M Jr.
10.1093/infdis/jiaa797 08/04/2021
PMID: 33367830
Background: To determine how serologic antibody testing outcome links with virus neutralization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), we evaluated individuals for SARS-CoV-2 antibody level and viral neutralization.
Methods: We compared serum Ig levels across platforms of viral antigens and antibodies with 15 positive and 30 negative SARS-CoV-2 controls followed by viral neutralization assessment. We then applied these platforms to a clinically relevant cohort of 114 individuals with unknown histories of SARS-CoV-2 infection.
Results: In controls, the best-performing virus-specific antibody detection platforms were SARS-CoV-2 receptor binding domain (RBD) IgG (sensitivity 87%, specificity 100%, positive predictive value [PPV] 100%, negative predictive value [NPV] 94%), spike IgG3 (sensitivity 93%, specificity 97%, PPV 93%, NPV 97%), and nucleocapsid protein (NP) IgG (sensitivity 93%, specificity 97%, PPV 93%, NPV 97%). Neutralization of positive and negative control sera showed 100% agreement. Twenty individuals with unknown history had detectable SARS-CoV-2 antibodies with 16 demonstrating virus neutralization. Spike IgG3 provided the highest accuracy for predicting serologically positive individuals with virus neutralization activity (misidentified 1/20 unknowns compared to 2/20 for RBD and NP IgG).
Conclusions: The coupling of virus neutralization analysis to a spike IgG3 antibody test is optimal to categorize patients for correlates of SARS-CoV-2 immune protection status.
Keywords: SARS-CoV-2; antibody; immunity; neutralization; serologic; two-tiered testing.
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