Role of IgM and IgA Antibodies in the Neutralization of SARS-CoV-2—Klinger 2020

SARS-CoV-2 has infected millions worldwide. Virus infection requires spike protein receptor-binding domain (RBD). In animal models, anti-spike and -RBD antibodies protect, and convalescent plasma is a promising treatment, but nothing is known about immunoglobulin (Ig) isotypes that can inhibit infection.

Methods: We used a multiplex bead assay to study spike- and RBD-specific Ig isotypes in convalescent and acute plasma/sera. VSV pseudovirus assays measured plasma, serum, and pure Ig fraction viral neutralization activities.

Results: Most participants generated spike- and RBD-specific IgM, IgG1, and IgA1 at varying levels early after infection. All samples neutralized. Regression studies showed that IgM and IgG1 neutralized most, commensurate with their potency. IgA neutralized, although weakly.

Conclusion: COVID-19 convalescent plasma needs IgG, IgM, and IgA.

Klingler, J., Weiss, S., Itri, V., Liu, X., Oguntuyo, K. Y., Stevens, C., Ikegame, S., Hung, C. T., Enyindah-Asonye, G., Amanat, F., Baine, I., Arinsburg, S., Bandres, J. C., Kojic, E. M., Stoever, J., Jurczyszak, D., Bermudez-Gonzalez, M., Nádas, A., Liu, S., Lee, B., … Hioe, C. E. (2020). Role of IgM and IgA Antibodies in the Neutralization of SARS-CoV-2. medRxiv : the preprint server for health sciences, 2020.08.18.20177303. https://doi.org/10.1101/2020.08.18.20177303