TY - JOUR T1 - Sensitivity of infectious SARS-CoV-2 B.1.1.7 and B.1.351 variants to neutralizing antibodies JF - bioRxiv DO - 10.1101/2021.02.12.430472 SP - 2021.02.12.430472 AU - Delphine Planas AU - Timothée Bruel AU - Ludivine Grzelak AU - Florence Guivel-Benhassine AU - Isabelle Staropoli AU - Françoise Porrot AU - Cyril Planchais AU - Julian Buchrieser AU - Maaran Michael Rajah AU - Elodie Bishop AU - Mélanie Albert AU - Flora Donati AU - Sylvie Behillil AU - Vincent Enouf AU - Marianne Maquart AU - Maria Gonzalez AU - Jérôme De Sèze AU - Hélène Péré AU - David Veyer AU - Aymeric Sève AU - Etienne Simon-Lorière AU - Samira Fafi-Kremer AU - Karl Stefic AU - Hugo Mouquet AU - Laurent Hocqueloux AU - Sylvie van der Werf AU - Thierry Prazuck AU - Olivier Schwartz Y1 - 2021/01/01 UR - http://biorxiv.org/content/early/2021/02/12/2021.02.12.430472.abstract N2 - SARS-CoV-2 B.1.1.7 and B.1.351 variants emerged respectively in United Kingdom and South Africa and spread in many countries. Here, we isolated infectious B.1.1.7 and B.1.351 strains and examined their sensitivity to anti-SARS-CoV-2 antibodies present in sera and nasal swabs, in comparison with a D614G reference virus. We established a novel rapid neutralization assay, based on reporter cells that become GFP+ after overnight infection. B.1.1.7 was neutralized by 79/83 sera from convalescent patients collected up to 9 months post symptoms, almost similar to D614G. There was a mean 6-fold reduction in titers and even loss of activity against B.1.351 in 40% of convalescent sera after 9 months. Early sera from 19 vaccinated individuals were almost as potent against B.1.1.7 but less efficacious against B.1.351, when compared to D614G. Nasal swabs from vaccine recipients were not neutralizing, except in individuals who were diagnosed COVID-19+ before vaccination. Thus, faster-spreading variants acquired a partial resistance to humoral immunity generated by natural infection or vaccination, mostly visible in individuals with low antibody levels.Competing Interest StatementThe authors have declared no competing interest. ER -