Single-cell RNA sequencing reveals the expansion of circulating tissue-homing B cell subsets in secondary acute dengue viral infection.

The roles of antibodies secreted by subsets of B cells in dengue virus (DENV) infection have been extensively studied, yet, the contribution of tissue-homing B cells to antiviral immunity remains unclear. In this study, we performed a comprehensive analysis of B cell subpopulations in peripheral blood samples from DENV-infected patients using single-cell RNA-sequencing (scRNA-seq) datasets and flow cytometry. We showed that plasma cells (PCs) and plasmablasts (PBs) were the predominant B cell populations during the acute phase of secondary natural DENV infection, but not in convalescent phase nor in healthy controls. Interestingly, these cells expressed proliferation, adhesion, and tissue-homing genes, including , a homing marker of the skin, the initial infected site of DENV. Flow cytometry analysis confirmed a significant upregulation of cell surface expression of a cutaneous lymphocyte-associated antigen (CLA) encoded by in PCs and PBs, compared to naive and memory B cells from the same patients. The analysis of an independent single-cell B-cell receptor sequencing (scBCR-seq) dataset of DENV-infected patients revealed that the peripheral blood PCs and PBs exhibited the highest clonal expansion in secondary DENV infection compared to other B cell subsets. These clonally expanded cells also expressed the highest levels of tissue-homing genes, including In addition, by utilizing a public scRNA-seq dataset of SARS-CoV2 infection, we demonstrated the upregulation of several tissue-homing genes in PCs and PBs. Our study provides evidence for the potential roles of tissue-homing B cell subsets in the context of immune responses against viral infections in humans.