Determinants of de novo B cell responses to drifted epitopes in post-vaccination SARS-CoV-2 infections

Vaccine-induced immunity may impact subsequent de novo responses to drifted epitopes in SARS-CoV-2 variants, but this has been difficult to quantify due to the challenges in recruiting unvaccinated control groups whose first exposure to SARS-CoV-2 is a primary infection. Through local, statewide, and national SARS-CoV-2 testing programs, we were able to recruit cohorts of individuals who had recovered from either primary or post-vaccination infections by either the Delta or Omicron BA.1 variants. Regardless of variant, we observed greater Spike-specific and neutralizing antibody responses in post-vaccination infections than in those who were infected without prior vaccination. Through analysis of variant-specific memory B cells as markers of de novo responses, we observed that Delta and Omicron BA.1 infections led to a marked shift in immunodominance in which some drifted epitopes elicited minimal responses, even in primary infections. Prior immunity through vaccination had a small negative impact on these de novo responses, but this did not correlate with cross-reactive memory B cells, arguing against competitive inhibition of naïve B cells. We conclude that dampened de novo B cell responses against drifted epitopes are mostly a function of altered immunodominance hierarchies that are apparent even in primary infections, with a more modest contribution from pre-existing immunity, perhaps due to accelerated antigen clearance. ### Competing Interest Statement Sana Biotechnology has licensed intellectual property of D.B. and Washington University in St. Louis. Gilead Sciences has licensed intellectual property of D.B. and Stanford University. Clade Therapeutics has licensed intellectual property of D.B. and University of Arizona. D.B. is a co-founder of Clade Therapeutics. D.B. served on an advisory panel for GlaxoSmithKline. B.J.L. has a financial interest in Cofactor Genomics, Inc. and Iron Horse Dx. Geneticure Inc. has licensed intellectual property of R.S. and R.S is a co-founder of Geneticure Inc. M.W. has received consulting fees from GLG on SARS-CoV-2 and the COVID-19 pandemic. ### Funding Statement This work was supported by NIH grants R01AI099108 and R01AI129945 (D.B.) and a research grant from the Arizona Board of Regents (M.W. and D.B). This project has been funded in part with Federal funds from the National Institute of Allergy and Infectious Diseases, National Institutes of Health, Department of Health and Human Services, under Contract No. 75N93021C00015 (M.W.) The HEROES-RECOVER cohort is supported by the National Center for Immunization and Respiratory Diseases and the Centers for Disease Control and Prevention (contracts 75D30120R68013 to Marshfield Clinic Research Institute, 75D30120C08379 to the University of Arizona, and 75D30120C08150 to Abt Associates). ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: IRB of The University of Arizona gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors