Clonal selection of cross-reactive memory B cells dominates recall responses against heterologous flaviviruses without a requirement for secondary affinity maturation

Abstract

Abstract Members of the flaviviridae family include a number of globally relevant pathogens such as West Nile (WNV), Japanese Encephalitis (JEV), Dengue, and Zika viruses. Upon clearance of a primary flavivirus infection, both neutralizing and non-neutralizing antibody specificities are generated and maintained. These antibodies can play protective or pathogenic roles after subsequent infection with heterologous flaviviruses. To define the cells capable of responding to secondary heterologous infections, we utilized a WNV and subsequent JEV vaccination model. Using tetramer reagents directed at the potently neutralizing lateral ridge epitope on envelope protein domain III (DIII) of WNV. We found that memory B cells were more antigenically diverse and cross-reactive than were long-lived plasma cells. To determine how this memory B cell diversity is generated and subsequently utilized, we generated a mouse model in which deletion of activation induced cytidine deaminase (AID) is temporally driven by hCD20-CreERT2. Deleting AID during ongoing germinal center reactions against WNV did not affect the antigen specificity or quantity of memory B cells or bone marrow plasma cells. Deletion of AID during the memory phase following WNV vaccination did not alter the cellular response to JEV compared to wild type mice. Thus, cross-reactive B cells selectively enter the memory B cell compartment and are excluded from the long-lived plasma cell compartment through a B cell receptor affinity maturation-independent mechanism. Analysis of germline-reverted monoclonal antibodies derived from DIII-specific memory B cells and long-lived plasma cells suggests that the fate of a B cell is imprinted at the naive state.