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Pre-existing neutralizing antibody provides the first line of defence against pathogens in general. For influenza virus, annual vaccinations are given to maintain protective levels of antibody against the currently circulating strains. Here we report that after booster vaccination there was a rapid and robust influenza-specific IgG+ antibody-secreting(More)
The 2009 pandemic H1N1 influenza pandemic demonstrated the global health threat of reassortant influenza strains. Herein, we report a detailed analysis of plasmablast and monoclonal antibody responses induced by pandemic H1N1 infection in humans. Unlike antibodies elicited by annual influenza vaccinations, most neutralizing antibodies induced by pandemic(More)
153 B-cell antigen receptor diversity is achieved by the assembly of antibody gene segments through V(D)J recombination (1). The random nature of the recombination process leads to the unavoidable production of self-reactive specifi cities, which are silenced both centrally and peripherally by clonal deletion, anergy, and receptor editing (2–6). Despite(More)
Pathogen pattern recognition receptors (PRRs) recognize common structural and molecular motifs present on microbial surfaces and contribute to induction of innate immune responses. The mannose receptor (MR), a carbohydrate-binding receptor expressed on subsets of macrophages, is considered one such PRR. In vitro experiments have implicated the MR in(More)
Self-reactive B cells not controlled by receptor editing or clonal deletion may become anergic. We report that fully mature human B cells negative for surface IgM and retaining only IgD are autoreactive and functionally attenuated (referred to as naive IgD(+)IgM(-) B cells [B(ND)]). These B(ND) cells typically make up 2.5% of B cells in the peripheral(More)
Interaction of a B cell expressing self-specific B-cell antigen receptor (BCR) with an auto-antigen results in either clonal deletion or functional inactivation. Both of these processes lead to B-cell tolerance and are essential for the prevention of auto-immune diseases. Whereas clonal deletion results in the death of developing autoreactive B cells,(More)
It is believed that immunoglobulin-variable region gene (IgV) somatic hypermutation (SHM) is initiated by activation-induced cytidine deaminase (AID) upon deamination of cytidine to deoxyuracil. Patch-excision repair of these lesions involving error prone DNA polymerases such as poleta causes mutations at all base positions. If not repaired, the deaminated(More)
UNLABELLED In 2009, a novel H1N1 influenza A virus (2009 pH1N1) emerged and caused a pandemic. A human monoclonal antibody (hMAb; EM4C04), highly specific for the 2009 pH1N1 virus hemagglutinin (HA), was isolated from a severely ill 2009 pH1N1 virus-infected patient. We postulated that under immune pressure with EM4C04, the 2009 pH1N1 virus would undergo(More)
Staphylococcus aureus bacterial infection commonly results in chronic or recurrent disease, suggesting that humoral memory responses are hampered. Understanding how S. aureus subverts the immune response is critical for the rescue of host natural humoral immunity and vaccine development. S. aureus expresses the virulence factor Protein A (SpA) on all(More)
The important subtleties of B cell tolerance are best understood in a diverse immunoglobulin (Ig) repertoire context encoding a full spectrum of autoreactivity. To achieve this, we used mice expressing Igκ transgenes that confer varying degrees of autoreactivity within a diverse heavy chain (HC) repertoire. These transgenes, coupled with a biomarker to(More)