CD27CD38 plasmablasts are activated B cells of mixed origin with distinct function.

Clinically important broadly reactive B cells evolve during multiple infections, with B cells re-activated after secondary infection differing from B cells activated after a primary infection. Here we studied CD27CD38 plasmablasts from patients with a primary or secondary dengue virus infection. Three transcriptionally and functionally distinct clusters were identified.

Immune cell phenotypes associated with disease severity and long-term neutralizing antibody titers after natural dengue virus infection.

Prior immunological exposure to dengue virus can be both protective and disease-enhancing during subsequent infections with different dengue virus serotypes. We provide here a systematic, longitudinal analysis of B cell, T cell, and antibody responses in the same patients. Antibody responses as well as T and B cell activation differentiate primary from secondary responses.

Influenza Virus Vaccination Elicits Poorly Adapted B Cell Responses in Elderly Individuals.

Influenza is a leading cause of death in the elderly, and the vaccine protects only a fraction of this population. A key aspect of antibody-mediated anti-influenza virus immunity is adaptation to antigenically distinct epitopes on emerging strains. We examined factors contributing to reduced influenza vaccine efficacy in the elderly and uncovered a dramatic reduction in the accumulation of de novo immunoglobulin gene somatic mutations upon vaccination.

Immune history profoundly affects broadly protective B cell responses to influenza.

Generating a broadly protective influenza vaccine is critical to global health. Understanding how immune memory influences influenza immunity is central to this goal. We undertook an in-depth study of the B cell response to the pandemic 2009 H1N1 vaccine over consecutive years.

High Affinity Antibodies against Influenza Characterize the Plasmablast Response in SLE Patients After Vaccination.

Breakdown of B cell tolerance is a cardinal feature of systemic lupus erythematosus (SLE). Increased numbers of autoreactive mature naïve B cells have been described in SLE patients and autoantibodies have been shown to arise from autoreactive and non-autoreactive precursors. How these defects, in the regulation of B cell tolerance and selection, influence germinal center (GC) reactions that are directed towards foreign antigens has yet to be investigated.

Preexisting human antibodies neutralize recently emerged H7N9 influenza strains.

The emergence and seasonal persistence of pathogenic H7N9 influenza viruses in China have raised concerns about the pandemic potential of this strain, which, if realized, would have a substantial effect on global health and economies. H7N9 viruses are able to bind to human sialic acid receptors and are also able to develop resistance to neuraminidase inhibitors without a loss in fitness. It is not clear whether prior exposure to circulating human influenza viruses or influenza vaccination confers immunity to H7N9 strains.

High preexisting serological antibody levels correlate with diversification of the influenza vaccine response.

Unlabelled: Reactivation of memory B cells allows for a rapid and robust immune response upon challenge with the same antigen. Variant influenza virus strains generated through antigenic shift or drift are encountered multiple times over the lifetime of an individual. One might predict, then, that upon vaccination with the trivalent influenza vaccine across multiple years, the antibody response would become more and more dominant toward strains consistently present in the vaccine at the expense of more divergent strains.

Staphylococcus aureus infection induces protein A-mediated immune evasion in humans.

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.

Complement-dependent lysis of influenza a virus-infected cells by broadly cross-reactive human monoclonal antibodies.

We characterized human monoclonal antibodies (MAbs) cloned from influenza virus-infected patients and from influenza vaccine recipients by complement-dependent lysis (CDL) assay. Most MAbs active in CDL were neutralizing, but not all neutralizing MAbs can mediate CDL. Two of the three stalk-specific neutralizing MAbs tested were able to mediate CDL and were more cross-reactive to temporally distant H1N1 strains than the conventional hemagglutination-inhibiting and neutralizing MAbs.

Targeting B cell responses in universal influenza vaccine design.

Since its first administration in the 1940s, the influenza vaccine has provided tremendous relief against influenza infections. However, time has revealed the ultimate limit of the vaccine and the call for its reinvention has now come, just as we are beginning to appreciate the antibody immune responses vital in preventing infections. New strategies to design the influenza vaccine rely on selectively inducing broadly neutralizing antibodies that are specific for highly conserved viral epitopes.

Harnessing the immune system's arsenal: producing human monoclonal antibodies for therapeutics and investigating immune responses.

Monoclonal antibody technology has undergone rapid and innovative reinvention over the last 30 years. Application of these technologies to human samples revealed valuable therapeutic and experimental insights. These technologies, each with their own benefits and flaws, have proven indispensable for immunological research and in our fight to provide new treatments and improved vaccines for infectious disease.

Broadly cross-reactive antibodies dominate the human B cell response against 2009 pandemic H1N1 influenza virus infection.

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 H1N1 infection were broadly cross-reactive against epitopes in the hemagglutinin (HA) stalk and head domain of multiple influenza strains.

Targeting hepatitis B virus-infected cells with a T-cell receptor-like antibody.

Virus-specific CD8 T cells are activated when their T-cell receptors (TCRs) recognize the specific viral peptide/major histocompatibility complex (MHC) class I (pMHC) complexes present on the surface of infected cells. Antibodies able to recognize the specific pMHC can mimic TCR specificity and both represent a valuable biological tool to visualize pMHC complexes on infected cells and serve as a delivery system for highly targeted therapies. To evaluate these possibilities, we created a monoclonal antibody able to specifically recognize a hepatitis B virus (HBV) envelope epitope (Env at positions 183 to 91 [Env183-91]) presented by the HLA-A201 molecule, and we tested its ability to recognize HBV-infected hepatocytes and to deliver a cargo to a specific target.