Dynamics of Dengue Virus (DENV)–Specific B Cells in the Response to DENV Serotype 1 Infections, Using Flow Cytometry With Labeled Virions

Background. The development of reagents to identify and characterize antigen-specific B cells has been challenging. Methods. We recently developed Alexa Fluor–labeled dengue viruses (AF DENVs) to characterize antigen-specific B cells in the peripheral blood of DENV-immune individuals. Results. In this study, we used AF DENV serotype 1 (AF DENV-1) together with AF DENV-2 on peripheral blood mononuclear cells (PBMCs) from children in Thailand with acute primary or secondary DENV-1 infections to analyze the phenotypes of antigen-specific B cells that reflected their exposure or clinical diagnosis. DENV serotype-specific and cross-reactive B cells were identified in PBMCs from all subjects. Frequencies of AF DENV+ class-switched memory B cells (IgD−CD27+ CD19+ cells) reached up to 8% during acute infection and early convalescence. AF DENV–labeled B cells expressed high levels of CD27 and CD38 during acute infection, characteristic of plasmablasts, and transitioned into memory B cells (CD38−CD27+) at the early convalescent time point. There was higher activation of memory B cells early during acute secondary infection, suggesting reactivation from a previous DENV infection. Conclusions. AF DENVs reveal changes in the phenotype of DENV serotype–specific and cross-reactive B cells during and after natural DENV infection and could be useful in analysis of the response to DENV vaccination.