Project description:Hybrid immunity (vaccination + natural infection) to SARS-CoV-2 provides superior protection to re-infection. We performed immune profiling studies during breakthrough infections in mRNA-vaccinated hamsters to evaluate hybrid immunity induction. Vaccine was dosed to induce binding antibody titers against ancestral spike, but not efficient virus neutralization of ancestral SARS-CoV-2 or variants of concern (VoCs). Vaccination reduced morbidity and controlled lung virus titers for ancestral virus and Alpha but allowed breakthrough infections in Beta, Delta and Mu-challenged hamsters. Vaccination primed for T cell responses that were boosted by infection. Infection back-boosted neutralizing antibody responses against ancestral virus and VoCs. Hybrid immunity resulted in more cross-reactive sera, reflected by smaller antigenic cartography distances. Transcriptomics post infection reflects both vaccination status and disease course, and suggests a role for interstitial macrophages in vaccine-mediated protection. Therefore, protection by vaccination, even in the absence of neutralizing antibodies, correlates with recall of broadly reactive B- and T-cell responses.
Project description:The aim of this study was to compare murine immune responses, particularly CD8+ T cell activation, in acute infection of either Ross River virus (RRV) or lymphocytic choriomeningitis virus (LCMV). LCMV induces a strong CD8+ T cell response that is required for viral clearance. RRV induces CD8+ T cells that only affect viral clearance in certain tissue and do not contribute to prevention of viral RNA persistence in lymphoid and joint-associated tissue. We sequenced cells from the draining lymph node at 5 days post infection to assess activation states of CD8+ T cells at this timepoint.
Project description:Combining variant antigens into a multivalent vaccine is a traditional approach used to provide broad coverage against antigenically variable pathogens, such as polio, human papilloma and influenza viruses. However, strategies for increasing the breadth of antibody coverage beyond the vaccine are not well understood, but may provide more anticipatory protection. Influenza virus hemagglutinin (HA) is a prototypic variant antigen. Vaccines that induce HA-specific neutralizing antibodies lose efficacy as amino acid substitutions accumulate in neutralizing epitopes during influenza virus evolution. Here we studied the effect of a potent combination adjuvant (CpG/MPLA/squalene-in-water emulsion) on the breadth and maturation of the antibody response to a representative variant of HA subtypes H1, H5 and H7. Using HA protein microarrays and antigen-specific B cell labelling, we show when administered individually, each HA elicits a cross-reactive antibody profile for multiple variants within the same subtype and other closely-related subtypes (homosubtypic and heterosubtypic cross-reactivity, respectively). Despite a capacity for each subtype to induce heterosubtypic cross-reactivity, broader coverage was elicited by simply combining the subtypes into a multivalent vaccine. Importantly, multiplexing did not compromise antibody avidity or affinity maturation to the individual HA constituents. The use of adjuvants to increase the breadth of antibody coverage beyond the vaccine antigens may help future-proof vaccines against newly-emerging variants.
Project description:Epitope mapping studies aim to identify the binding sites of antibody-antigen interactions to enhance the development of vaccines, diagnostics and immunotherapeutic compounds. However, mapping is a laborious process employing time- and resource-consuming M-bM-^@M-^Xwet benchM-bM-^@M-^Y techniques or epitope prediction software that are still in their infancy. For polymorphic antigens, another challenge is characterizing cross-reactivity between epitopes, teasing out distinctions between broadly cross-reactive responses, limited cross-reactions among variants and the truly type-specific responses. A refined understanding of cross-reactive antibody binding could guide the selection of the most informative subsets of variants for diagnostics and multivalent subunit vaccines. We explored the antibody binding reactivity of sera from human patients and Peromyscus leucopus rodents infected with Borrelia burgdorferi to the polymorphic outer surface protein C (OspC), an attractive candidate antigen for vaccine and improved diagnostics for Lyme disease. We constructed a protein microarray displaying 23 natural variants of OspC and quantified the degree of cross-reactive antibody binding between all pairs of variants, using Pearson correlation calculated on the reactivity values using three independent transforms of the raw data: (1) logarithmic, (2) rank, and (3) binary indicators. We observed that the global amino acid sequence identity between OspC pairs was a poor predictor of cross-reactive antibody binding. Then we asked if specific regions of the protein would better explain the observed cross-reactive binding and performed in silico screening of the linear sequence and 3-dimensional structure of OspC. This analysis pointed to the C-terminal helix of the structure as a major determinant of type-specific cross-reactive antibody binding. We developed bioinformatics methods to systematically analyze the relationship between local sequence/structure variation and cross-reactive antibody binding patterns among variants of a polymorphic antigen, and this method can be applied to other polymorphic antigens for which immune response data is available for multiple variants. Antibody profiling was performed on sera from Borrelia burgdorferi infected and non-infected humans and Peromyscus leucopus rodents against 23 variants of the surface protein OspC . For infected human serum samples, the OspC type of the infecting B. burgdorferi strain is unknown; for experimentally-infected P. leucopus serum samples, it is known. Of human serum samples, 55 were from infected individuals and 25 from naive controls. Of P. leucopus serum samples, 23 were from infected individuals and 7 were from naive controls.
Project description:Effective vaccines against viruses such as Influenza and SARS-CoV-2 must elicit a diverse repertoire of antibodies against multiple variant virus strains. However, antibody responses to current vaccines often lack cross-reactivity due to immunodominance. Here, we describe the synthesis of a toll-like receptor 7 agonist (TLR7)-nanoparticle adjuvant, TLR7-NP, constructed from TLR7 agonist-initiated ring-opening polymerization of lactide and self-assembly with poly(ethylene glycol)-b-poly(lactic-co-glycolic acid). TLR7-NP can enhance lymph node targeting, leading to persistent activation of immune cells. When mixed with Alum-adsorbed antigens, this TLR7-NP adjuvant elicited cross-reactive antibodies for both dominant and subdominant epitopes, as well as antigen-specific CD8+ T cell responses, in mice. TLR7-NP adjuvanted influenza subunit vaccine successfully protected mice from heterologous viral challenge. TLR7-NP also enhanced the antibody response to a SARS-CoV-2 subunit vaccine against multiple variants and revealed the mobilization of an antiviral response. We further demonstrate enhanced antigen-specific responses in human tonsil organoids with this novel adjuvant.
Project description:Epitope mapping studies aim to identify the binding sites of antibody-antigen interactions to enhance the development of vaccines, diagnostics and immunotherapeutic compounds. However, mapping is a laborious process employing time- and resource-consuming ‘wet bench’ techniques or epitope prediction software that are still in their infancy. For polymorphic antigens, another challenge is characterizing cross-reactivity between epitopes, teasing out distinctions between broadly cross-reactive responses, limited cross-reactions among variants and the truly type-specific responses. A refined understanding of cross-reactive antibody binding could guide the selection of the most informative subsets of variants for diagnostics and multivalent subunit vaccines. We explored the antibody binding reactivity of sera from human patients and Peromyscus leucopus rodents infected with Borrelia burgdorferi to the polymorphic outer surface protein C (OspC), an attractive candidate antigen for vaccine and improved diagnostics for Lyme disease. We constructed a protein microarray displaying 23 natural variants of OspC and quantified the degree of cross-reactive antibody binding between all pairs of variants, using Pearson correlation calculated on the reactivity values using three independent transforms of the raw data: (1) logarithmic, (2) rank, and (3) binary indicators. We observed that the global amino acid sequence identity between OspC pairs was a poor predictor of cross-reactive antibody binding. Then we asked if specific regions of the protein would better explain the observed cross-reactive binding and performed in silico screening of the linear sequence and 3-dimensional structure of OspC. This analysis pointed to the C-terminal helix of the structure as a major determinant of type-specific cross-reactive antibody binding. We developed bioinformatics methods to systematically analyze the relationship between local sequence/structure variation and cross-reactive antibody binding patterns among variants of a polymorphic antigen, and this method can be applied to other polymorphic antigens for which immune response data is available for multiple variants.
Project description:Universal vaccines cross-protecting against sarbecoviruses including SARS-CoV-2 are in great need under continuous emergence of SARS-CoV-2 variants and potential novel coronavirus. Nanoparicle vaccines displaying mosaic receptor-binding domains (RBDs) or spike (S) proteins from SARS-CoV-2 and other sarbecoviruses were used for preparedness to emergent zoonotic outbreak. Here, we describe a self-assembling nanoparticle using lumazine synthase (LuS) as the scaffold to display RBDs from different sarbecoviruses. The mosaic LuS-RBD vaccines induced cross-reactive binding and neutralizing antibody responses to sarbecoviruses. Single B cell sequencing revealed that mosaic LuS-RBD elicited B-cell receptor (BCR) repertoire using an immunodominant germline gene pair of IGHV14-3: IGKV14-111 in mice. Most of the tested IGHV14-3: IGKV14-111 monoclonal antibodies (mAbs) are broadly cross-reactive to the clade 1a, 1b and 3 sarbecoviruses. By antibody binning and cryo-electron microscopy, we determined a reprensentative IGHV14-3: IGKV14-111 mAb, M2-7, bound to an conserved epitope on RBD largely overlapping with a pan-sarbecovirus mAb S2H97, which suggested that mosaic nanoparticles expended B cells recognizing the common epitopes shared by different clades of sarbecoviruses. These results provide immunological insights into the cross-reactive responses elicited by mosaic nanoparticle against emerging sarbecoviruses.
Project description:Influenza virus vaccination remains the best strategy for combating virus infection, but vaccine efficacy is highly variable. An ideal influenza vaccine must have two attributes: one, it should be capable of inducing broadly cross-reactive antibodies that can neutralize diverse influenza virus strains; and two, it must induce long-lived antibody responses to maintain protective immunity for extended periods. Germinal center (GC) reactions are the major sites where diversification and affinity maturation of B cells occur. Whether a persistent GC response could expand the breadth of responding B cell clones following influenza vaccination in humans remains unknown. Here, we show that influenza virus vaccine-specific GC B cells persist for over nine weeks post vaccination in two out of seven individuals. These late vaccine-specific GC B cells exhibited increased somatic hypermutation (SHM) of their B cell receptors compared to early vaccine-specific GC B cells. After re-immunization with seasonal influenza virus vaccine, individuals with a persistent GC engaged vaccine-specific plasmablasts (PBs) with higher SHM frequency. Tracking the maturation of three clonally related GC B cell lineages over time revealed that late GC B cells had receptors that recognized and neutralized heterologous influenza virus strains. Thus, SHM induced by persistent GCs can broaden the antibody response to influenza virus vaccination. This indicates that seasonal influenza virus vaccination in humans can induce broadly cross-reactive antibodies that target diverse influenza virus strains.
Project description:Influenza virus vaccination remains the best strategy for combating virus infection, but vaccine efficacy is highly variable. An ideal influenza vaccine must have two attributes: one, it should be capable of inducing broadly cross-reactive antibodies that can neutralize diverse influenza virus strains; and two, it must induce long-lived antibody responses to maintain protective immunity for extended periods. Germinal center (GC) reactions are the major sites where diversification and affinity maturation of B cells occur. Whether a persistent GC response could expand the breadth of responding B cell clones following influenza vaccination in humans remains unknown. Here, we show that influenza virus vaccine-specific GC B cells persist for over nine weeks post vaccination in two out of seven individuals. These late vaccine-specific GC B cells exhibited increased somatic hypermutation (SHM) of their B cell receptors compared to early vaccine-specific GC B cells. After re-immunization with seasonal influenza virus vaccine, individuals with a persistent GC engaged vaccine-specific plasmablasts (PBs) with higher SHM frequency. Tracking the maturation of three clonally related GC B cell lineages over time revealed that late GC B cells had receptors that recognized and neutralized heterologous influenza virus strains. Thus, SHM induced by persistent GCs can broaden the antibody response to influenza virus vaccination. This indicates that seasonal influenza virus vaccination in humans can induce broadly cross-reactive antibodies that target diverse influenza virus strains.
Project description:Recent exposure to seasonal coronaviruses (sCoVs) may stimulate cross-reactive antibody responses against SARS-CoV-2. Previous studies have shown divergent results regarding protective or damaging immunity induced by prior exposure to sCoVs. It is still unknown whether pre-existing humoral immunity may play a role in the vaccine-induced neutralization and antibody responses. In this study, we collected 36 paired sera in healthy volunteers before and after immunization with inactivated SARS-CoV-2 vaccines, and analyzed the distribution and intensity of pre-existing antibody responses at the epitope level before vaccine immunization, as well as the relationship between pre-existing sCoVs immunity and vaccine-induced neutralization.