IFN-gene signatures in B cells following influenza A and B virus infection and influenza vaccination.

Influenza viruses continue to cause a substantial global disease burden. Despite influenza vaccination, some individuals succumb to life-threatening influenza or death. Yet our understanding of immune features elicited by vaccination and influenza A and B virus (IAV, IBV) infection is limited. To define molecular signatures of influenza-specific B-cells, we performed scRNA-sequencing of influenza-specific B-cells in vaccinees and hospitalized IAV/IBV-infected patients using HA-probes. We observed increased interferon-stimulated gene signatures (IF44L, IFITM1 and XAF1), in total B-cells from IBV-patients, but not at 1-month following patients' recovery or in IAV-patients or vaccinees. Phenotypic differentiation and isotype class-switching of HA-specific B-cells were observed following vaccination, with clonal sharing between memory and atypical B-cell phenotypes. In-vitro influenza virus infection experiments showed IBVs having higher infectivity of human PBMCs, including B-cells, and reduced B-cell proliferation compared to IAV, potentially associated with antiproliferative effect of IFITM1. We provide key insights into B-cell immunity towards IBV and IAV infections and vaccination, which will inform rational vaccine design and therapeutic strategies aimed at eliciting robust HA-specific B-cell responses, while minimizing adverse effects caused by natural infection.