Role of Immunoglobulin M and A Antibodies in the Neutralization of Severe Acute Respiratory Syndrome Coronavirus 2—Klinger 2021

Background: Millions have contracted SARS-CoV-2. Virus infection requires spike protein receptor-binding domain (RBD). Anti-spike and -RBD antibodies protect animals, and convalescent plasma is a promising treatment, but nothing is known about immunoglobulin isotypes that can inhibit infection.

Methods: A multiplex bead test examined spike- and RBD-specific immunoglobulin isotypes in convalescent and acute plasma/serum samples. We measured plasma and serum viral neutralization and isolated immunoglobulin fractions using a vesicular stomatitis pseudovirus test.

Results: All or nearly all participants developed 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. (2021). Role of Immunoglobulin M and A Antibodies in the Neutralization of Severe Acute Respiratory Syndrome Coronavirus 2. The Journal of infectious diseases, 223(6), 957–970. https://doi.org/10.1093/infdis/jiaa784