RESUMEN
Coronavirus disease 2019 (COVID-19) exhibits variable symptom severity ranging from asymptomatic to life-threatening, yet the relationship between severity and the humoral immune response is poorly understood. We examined antibody responses in 113 COVID-19 patients and found that severe cases resulting in intubation or death exhibited increased inflammatory markers, lymphopenia, pro-inflammatory cytokines, and high anti-receptor binding domain (RBD) antibody levels. Although anti-RBD immunoglobulin G (IgG) levels generally correlated with neutralization titer, quantitation of neutralization potency revealed that high potency was a predictor of survival. In addition to neutralization of wild-type SARS-CoV-2, patient sera were also able to neutralize the recently emerged SARS-CoV-2 mutant D614G, suggesting cross-protection from reinfection by either strain. However, SARS-CoV-2 sera generally lacked cross-neutralization to a highly homologous pre-emergent bat coronavirus, WIV1-CoV, which has not yet crossed the species barrier. These results highlight the importance of neutralizing humoral immunity on disease progression and the need to develop broadly protective interventions to prevent future coronavirus pandemics.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , Biomarcadores/análisis , COVID-19/inmunología , COVID-19/fisiopatología , Adulto , Anticuerpos Neutralizantes/análisis , Anticuerpos Antivirales/análisis , Anticuerpos Antivirales/sangre , Biomarcadores/sangre , COVID-19/sangre , COVID-19/epidemiología , Comorbilidad , Coronavirus/clasificación , Coronavirus/fisiología , Reacciones Cruzadas , Citocinas/sangre , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Inmunoglobulina A/análisis , Inmunoglobulina G/sangre , Inmunoglobulina G/inmunología , Inmunoglobulina M/sangre , Inmunoglobulina M/inmunología , Masculino , Massachusetts/epidemiología , Persona de Mediana Edad , Dominios Proteicos , SARS-CoV-2/química , SARS-CoV-2/fisiología , Índice de Severidad de la Enfermedad , Glicoproteína de la Espiga del Coronavirus/química , Análisis de Supervivencia , Resultado del TratamientoRESUMEN
SARS-CoV-2-neutralizing antibodies (NAbs) protect against COVID-19. A concern regarding SARS-CoV-2 antibodies is whether they mediate disease enhancement. Here, we isolated NAbs against the receptor-binding domain (RBD) or the N-terminal domain (NTD) of SARS-CoV-2 spike from individuals with acute or convalescent SARS-CoV-2 or a history of SARS-CoV infection. Cryo-electron microscopy of RBD and NTD antibodies demonstrated function-specific modes of binding. Select RBD NAbs also demonstrated Fc receptor-γ (FcγR)-mediated enhancement of virus infection in vitro, while five non-neutralizing NTD antibodies mediated FcγR-independent in vitro infection enhancement. However, both types of infection-enhancing antibodies protected from SARS-CoV-2 replication in monkeys and mice. Three of 46 monkeys infused with enhancing antibodies had higher lung inflammation scores compared to controls. One monkey had alveolar edema and elevated bronchoalveolar lavage inflammatory cytokines. Thus, while in vitro antibody-enhanced infection does not necessarily herald enhanced infection in vivo, increased lung inflammation can rarely occur in SARS-CoV-2 antibody-infused macaques.
Asunto(s)
Anticuerpos Neutralizantes/inmunología , SARS-CoV-2/fisiología , Glicoproteína de la Espiga del Coronavirus/inmunología , Animales , Anticuerpos Antivirales/inmunología , Líquido del Lavado Bronquioalveolar/química , COVID-19/patología , COVID-19/virología , Citocinas/metabolismo , Femenino , Haplorrinos , Humanos , Pulmón/patología , Pulmón/virología , Masculino , Ratones , Ratones Endogámicos BALB C , Dominios Proteicos , ARN Guía de Kinetoplastida/metabolismo , Receptores de IgG/metabolismo , SARS-CoV-2/aislamiento & purificación , Glicoproteína de la Espiga del Coronavirus/química , Carga Viral , Replicación ViralRESUMEN
Antibodies are key immune effectors that confer protection against pathogenic threats. The nature and longevity of the antibody response to SARS-CoV-2 infection are not well defined. We charted longitudinal antibody responses to SARS-CoV-2 in 92 subjects after symptomatic COVID-19. Antibody responses to SARS-CoV-2 are unimodally distributed over a broad range, with symptom severity correlating directly with virus-specific antibody magnitude. Seventy-six subjects followed longitudinally to â¼100 days demonstrated marked heterogeneity in antibody duration dynamics. Virus-specific IgG decayed substantially in most individuals, whereas a distinct subset had stable or increasing antibody levels in the same time frame despite similar initial antibody magnitudes. These individuals with increasing responses recovered rapidly from symptomatic COVID-19 disease, harbored increased somatic mutations in virus-specific memory B cell antibody genes, and had persistent higher frequencies of previously activated CD4+ T cells. These findings illuminate an efficient immune phenotype that connects symptom clearance speed to differential antibody durability dynamics.
Asunto(s)
Anticuerpos Antivirales/inmunología , Formación de Anticuerpos , Linfocitos T CD4-Positivos/inmunología , COVID-19 , Inmunoglobulina G/inmunología , Activación de Linfocitos , Mutación , COVID-19/genética , COVID-19/inmunología , Humanos , SARS-CoV-2/genética , SARS-CoV-2/inmunologíaRESUMEN
We show that SARS-CoV-2 spike protein interacts with both cellular heparan sulfate and angiotensin-converting enzyme 2 (ACE2) through its receptor-binding domain (RBD). Docking studies suggest a heparin/heparan sulfate-binding site adjacent to the ACE2-binding site. Both ACE2 and heparin can bind independently to spike protein in vitro, and a ternary complex can be generated using heparin as a scaffold. Electron micrographs of spike protein suggests that heparin enhances the open conformation of the RBD that binds ACE2. On cells, spike protein binding depends on both heparan sulfate and ACE2. Unfractionated heparin, non-anticoagulant heparin, heparin lyases, and lung heparan sulfate potently block spike protein binding and/or infection by pseudotyped virus and authentic SARS-CoV-2 virus. We suggest a model in which viral attachment and infection involves heparan sulfate-dependent enhancement of binding to ACE2. Manipulation of heparan sulfate or inhibition of viral adhesion by exogenous heparin presents new therapeutic opportunities.
Asunto(s)
Betacoronavirus/fisiología , Heparitina Sulfato/metabolismo , Peptidil-Dipeptidasa A/metabolismo , Glicoproteína de la Espiga del Coronavirus/metabolismo , Secuencia de Aminoácidos , Enzima Convertidora de Angiotensina 2 , Betacoronavirus/aislamiento & purificación , Sitios de Unión , COVID-19 , Línea Celular , Infecciones por Coronavirus/patología , Infecciones por Coronavirus/virología , Heparina/química , Heparina/metabolismo , Heparitina Sulfato/química , Humanos , Riñón/metabolismo , Pulmón/metabolismo , Simulación de Dinámica Molecular , Pandemias , Peptidil-Dipeptidasa A/química , Neumonía Viral/patología , Neumonía Viral/virología , Unión Proteica , Dominios Proteicos , Proteínas Recombinantes/biosíntesis , Proteínas Recombinantes/química , Proteínas Recombinantes/aislamiento & purificación , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus/química , Glicoproteína de la Espiga del Coronavirus/genética , Internalización del VirusRESUMEN
Humoral responses in coronavirus disease 2019 (COVID-19) are often of limited durability, as seen with other human coronavirus epidemics. To address the underlying etiology, we examined post mortem thoracic lymph nodes and spleens in acute SARS-CoV-2 infection and observed the absence of germinal centers and a striking reduction in Bcl-6+ germinal center B cells but preservation of AID+ B cells. Absence of germinal centers correlated with an early specific block in Bcl-6+ TFH cell differentiation together with an increase in T-bet+ TH1 cells and aberrant extra-follicular TNF-α accumulation. Parallel peripheral blood studies revealed loss of transitional and follicular B cells in severe disease and accumulation of SARS-CoV-2-specific "disease-related" B cell populations. These data identify defective Bcl-6+ TFH cell generation and dysregulated humoral immune induction early in COVID-19 disease, providing a mechanistic explanation for the limited durability of antibody responses in coronavirus infections, and suggest that achieving herd immunity through natural infection may be difficult.
Asunto(s)
Infecciones por Coronavirus/inmunología , Centro Germinal/inmunología , Neumonía Viral/inmunología , Linfocitos T Colaboradores-Inductores/inmunología , Anciano , Anciano de 80 o más Años , Linfocitos B/inmunología , COVID-19 , Femenino , Centro Germinal/patología , Humanos , Masculino , Persona de Mediana Edad , Pandemias , Proteínas Proto-Oncogénicas c-bcl-6/genética , Proteínas Proto-Oncogénicas c-bcl-6/metabolismo , Bazo/inmunología , Bazo/patología , Factor de Necrosis Tumoral alfa/metabolismoRESUMEN
Vaccines to generate durable humoral immunity against antigenically evolving pathogens such as the influenza virus must elicit antibodies that recognize conserved epitopes. Analysis of single memory B cells from immunized human donors has led us to characterize a previously unrecognized epitope of influenza hemagglutinin (HA) that is immunogenic in humans and conserved among influenza subtypes. Structures show that an unrelated antibody from a participant in an experimental infection protocol recognized the epitope as well. IgGs specific for this antigenic determinant do not block viral infection in vitro, but passive administration to mice affords robust IgG subtype-dependent protection against influenza infection. The epitope, occluded in the pre-fusion form of HA, is at the contact surface between HA head domains; reversible molecular "breathing" of the HA trimer can expose the interface to antibody and B cells. Antigens that present this broadly immunogenic HA epitope may be good candidates for inclusion in "universal" flu vaccines.
Asunto(s)
Anticuerpos Antivirales/inmunología , Epítopos/inmunología , Glicoproteínas Hemaglutininas del Virus de la Influenza/inmunología , Inmunoglobulina G/inmunología , Virus de la Influenza A/inmunología , Vacunas contra la Influenza/inmunología , Infecciones por Orthomyxoviridae , Adulto , Animales , Perros , Femenino , Humanos , Células de Riñón Canino Madin Darby , Masculino , Ratones , Persona de Mediana Edad , Infecciones por Orthomyxoviridae/inmunología , Infecciones por Orthomyxoviridae/patología , Infecciones por Orthomyxoviridae/prevención & controlRESUMEN
A safe and effective vaccine for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may be required to end the coronavirus disease 2019 (COVID-19) pandemic1-8. For global deployment and pandemic control, a vaccine that requires only a single immunization would be optimal. Here we show the immunogenicity and protective efficacy of a single dose of adenovirus serotype 26 (Ad26) vector-based vaccines expressing the SARS-CoV-2 spike (S) protein in non-human primates. Fifty-two rhesus macaques (Macaca mulatta) were immunized with Ad26 vectors that encoded S variants or sham control, and then challenged with SARS-CoV-2 by the intranasal and intratracheal routes9,10. The optimal Ad26 vaccine induced robust neutralizing antibody responses and provided complete or near-complete protection in bronchoalveolar lavage and nasal swabs after SARS-CoV-2 challenge. Titres of vaccine-elicited neutralizing antibodies correlated with protective efficacy, suggesting an immune correlate of protection. These data demonstrate robust single-shot vaccine protection against SARS-CoV-2 in non-human primates. The optimal Ad26 vector-based vaccine for SARS-CoV-2, termed Ad26.COV2.S, is currently being evaluated in clinical trials.
Asunto(s)
Betacoronavirus/inmunología , Infecciones por Coronavirus/inmunología , Infecciones por Coronavirus/prevención & control , Macaca mulatta , Pandemias/prevención & control , Neumonía Viral/inmunología , Neumonía Viral/prevención & control , Vacunas Virales/administración & dosificación , Vacunas Virales/inmunología , Animales , COVID-19 , Vacunas contra la COVID-19 , Modelos Animales de Enfermedad , Femenino , Inmunidad Celular , Inmunidad Humoral , Macaca mulatta/inmunología , Macaca mulatta/virología , Masculino , SARS-CoV-2 , Vacunación , Carga ViralRESUMEN
The predominant approach for antibody generation remains animal immunization, which can yield exceptionally selective and potent antibody clones owing to the powerful evolutionary process of somatic hypermutation. However, animal immunization is inherently slow, not always accessible and poorly compatible with many antigens. Here, we describe 'autonomous hypermutation yeast surface display' (AHEAD), a synthetic recombinant antibody generation technology that imitates somatic hypermutation inside engineered yeast. By encoding antibody fragments on an error-prone orthogonal DNA replication system, surface-displayed antibody repertoires continuously mutate through simple cycles of yeast culturing and enrichment for antigen binding to produce high-affinity clones in as little as two weeks. We applied AHEAD to generate potent nanobodies against the SARS-CoV-2 S glycoprotein, a G-protein-coupled receptor and other targets, offering a template for streamlined antibody generation at large.
Asunto(s)
Formación de Anticuerpos/inmunología , Ingeniería de Proteínas/métodos , Proteínas Recombinantes/biosíntesis , Anticuerpos/inmunología , Antígenos , COVID-19/inmunología , Humanos , Biblioteca de Péptidos , Proteínas Recombinantes/metabolismo , SARS-CoV-2/inmunología , SARS-CoV-2/patogenicidad , Saccharomyces cerevisiae/metabolismo , Anticuerpos de Dominio Único/genética , Anticuerpos de Dominio Único/metabolismo , Glicoproteína de la Espiga del Coronavirus/inmunologíaRESUMEN
The diagnosis of COVID-19 requires integration of clinical and laboratory data. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) diagnostic assays play a central role in diagnosis and have fixed technical performance metrics. Interpretation becomes challenging because the clinical sensitivity changes as the virus clears and the immune response emerges. Our goal was to examine the clinical sensitivity of two most common SARS-CoV-2 diagnostic test modalities, polymerase chain reaction (PCR) and serology, over the disease course to provide insight into their clinical interpretation in patients presenting to the hospital. We conducted a single-center, retrospective study. To derive clinical sensitivity of PCR, we identified 209 PCR-positive SARS-CoV-2 patients with multiple PCR test results (624 total PCR tests) and calculated daily sensitivity from date of symptom onset or first positive test. Clinical sensitivity of PCR decreased with days post symptom onset with >90% clinical sensitivity during the first 5 days after symptom onset, 70%-71% from Days 9 to 11, and 30% at Day 21. To calculate daily clinical sensitivity by serology, we utilized 157 PCR-positive patients with a total of 197 specimens tested by enzyme-linked immunosorbent assay for IgM, IgG, and IgA anti-SARS-CoV-2 antibodies. In contrast to PCR, serological sensitivity increased with days post symptom onset with >50% of patients seropositive by at least one antibody isotype after Day 7, >80% after Day 12, and 100% by Day 21. Taken together, PCR and serology are complimentary modalities that require time-dependent interpretation. Superimposition of sensitivities over time indicate that serology can function as a reliable diagnostic aid indicating recent or prior infection.
Asunto(s)
Prueba de Ácido Nucleico para COVID-19 , Prueba Serológica para COVID-19 , COVID-19/diagnóstico , SARS-CoV-2 , Anticuerpos Antivirales/sangre , COVID-19/sangre , Femenino , Hospitales , Humanos , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Sensibilidad y EspecificidadRESUMEN
SARS-CoV-2 antibody testing allows quantitative determination of disease prevalence, which is especially important in high-risk communities. We performed anonymized convenience sampling of 200 currently asymptomatic residents of Chelsea, the epicenter of COVID-19 illness in Massachusetts, by BioMedomics SARS-CoV-2 combined IgM-IgG point-of-care lateral flow immunoassay. The seroprevalence was 31.5% (17.5% IgM+IgG+, 9.0% IgM+IgG-, and 5.0% IgM-IgG+). Of the 200 participants, 50.5% reported no symptoms in the preceding 4 weeks, of which 24.8% (25/101) were seropositive, and 60% of these were IgM+IgG-. These data are the highest seroprevalence rates observed to date and highlight the significant burden of asymptomatic infection.
Asunto(s)
Anticuerpos Antivirales/sangre , COVID-19/diagnóstico , Sistemas de Atención de Punto , Adulto , Especificidad de Anticuerpos , COVID-19/epidemiología , COVID-19/virología , Ensayo de Inmunoadsorción Enzimática , Femenino , Humanos , Inmunoensayo , Inmunoglobulina G/sangre , Inmunoglobulina M/sangre , Masculino , Massachusetts/epidemiología , Persona de Mediana Edad , Análisis Multivariante , Análisis de Regresión , Estudios SeroepidemiológicosRESUMEN
To study factors that affect WPD-loop motion in protein tyrosine phosphatases (PTPs), a chimera of PTP1B and YopH was created by transposing the WPD loop from PTP1B to YopH. Several subsequent mutations proved to be necessary to obtain a soluble, active enzyme. That chimera, termed chimera 3, retains productive WPD-loop motions and general acid catalysis with a pH dependency similar to that of the native enzymes. Kinetic isotope effects show the mechanism and transition state for phosphoryl transfer are unaltered. Catalysis of the chimera is slower than that of either of its parent enzymes, although its rate is comparable to those of most native PTPs. X-ray crystallography and nuclear magnetic resonance were used to probe the structure and dynamics of chimera 3. The chimera's structure was found to sample an unproductive hyper-open conformation of its WPD loop, a geometry that has not been observed in either of the parents or in other native PTPs. The reduced catalytic rate is attributed to the protein's sampling of this conformation in solution, reducing the fraction in the catalytically productive loop-closed conformation.
Asunto(s)
Proteínas de la Membrana Bacteriana Externa/química , Proteínas de la Membrana Bacteriana Externa/metabolismo , Proteína Tirosina Fosfatasa no Receptora Tipo 1/química , Proteína Tirosina Fosfatasa no Receptora Tipo 1/metabolismo , Proteínas Tirosina Fosfatasas/química , Proteínas Tirosina Fosfatasas/metabolismo , Proteínas Recombinantes de Fusión/química , Proteínas Recombinantes de Fusión/metabolismo , Yersinia/enzimología , Secuencia de Aminoácidos , Proteínas de la Membrana Bacteriana Externa/genética , Sitios de Unión , Catálisis , Dominio Catalítico , Cristalografía por Rayos X , Humanos , Modelos Moleculares , Conformación Proteica , Dominios Proteicos , Proteína Tirosina Fosfatasa no Receptora Tipo 1/genética , Proteínas Tirosina Fosfatasas/genética , Proteínas Recombinantes de Fusión/genética , Homología de SecuenciaRESUMEN
Immunogens that elicit broadly neutralizing antibodies targeting the conserved receptor-binding site (RBS) on influenza hemagglutinin may serve as candidates for a universal influenza vaccine. Here, we develop a computational model to interrogate antibody evolution by affinity maturation after immunization with two types of immunogens: a heterotrimeric "chimera" hemagglutinin that is enriched for the RBS epitope relative to other B cell epitopes and a cocktail composed of three non-epitope-enriched homotrimers of the monomers that comprise the chimera. Experiments in mice find that the chimera outperforms the cocktail for eliciting RBS-directed antibodies. We show that this result follows from an interplay between how B cells engage these antigens and interact with diverse helper T cells and requires T cell-mediated selection of germinal center B cells to be a stringent constraint. Our results shed light on antibody evolution and highlight how immunogen design and T cells modulate vaccination outcomes.
Asunto(s)
Vacunas contra la Influenza , Gripe Humana , Animales , Ratones , Humanos , Anticuerpos Antivirales , Anticuerpos Neutralizantes , Hemaglutininas , Glicoproteínas Hemaglutininas del Virus de la Influenza , VacunaciónRESUMEN
Low affinity is common for germline B cell receptors (BCR) seeding development of broadly neutralizing antibodies (bnAbs) that engage hypervariable viruses, including HIV. Antibody affinity selection is also non-homogenizing, insuring the survival of low affinity B cell clones. To explore whether this provides a natural window for expanding human B cell lineages against conserved vaccine targets, we deploy transgenic mice mimicking human antibody diversity and somatic hypermutation (SHM) and immunize with simple monomeric HIV glycoprotein envelope immunogens. We report an immunization regimen that focuses B cell memory upon the conserved CD4 binding site (CD4bs) through both conventional affinity maturation and reproducible expansion of low affinity BCR clones with public patterns in SHM. In the latter instance, SHM facilitates target acquisition by decreasing binding strength. This suggests that permissive B cell selection enables the discovery of antibody epitopes, in this case an HIV bnAb site.
Asunto(s)
Vacunas contra el SIDA , Infecciones por VIH , Humanos , Animales , Ratones , Linfocitos B , Células B de Memoria , Receptores de Antígenos de Linfocitos B/genética , Anticuerpos ampliamente neutralizantes , Antígenos VIH , Ratones Transgénicos , Infecciones por VIH/prevención & controlRESUMEN
Enveloped viruses co-opt host glycosylation pathways to decorate their surface proteins. As viruses evolve, emerging strains can modify their glycosylation patterns to influence host interactions and subvert immune recognition. Still, changes in viral glycosylation or their impact on antibody protection cannot be predicted from genomic sequences alone. Using the highly glycosylated SARS-CoV-2 Spike protein as a model system, we present a lectin fingerprinting method that rapidly reports on changes in variant glycosylation state, which are linked to antibody neutralization. In the presence of antibodies or convalescent and vaccinated patient sera, unique lectin fingerprints emerge that distinguish neutralizing versus non-neutralizing antibodies. This information could not be inferred from direct binding interactions between antibodies and the Spike receptor-binding domain (RBD) binding data alone. Comparative glycoproteomics of the Spike RBD of wild-type (Wuhan-Hu-1) and Delta (B.1.617.2) variants reveal O-glycosylation differences as a key determinant of immune recognition differences. These data underscore the interplay between viral glycosylation and immune recognition and reveal lectin fingerprinting to be a rapid, sensitive, and high-throughput assay to distinguish the neutralization potential of antibodies that target critical viral glycoproteins.
RESUMEN
Development of SARS-CoV-2 vaccines that protect vulnerable populations is a public health priority. Here, we took a systematic and iterative approach by testing several adjuvants and SARS-CoV-2 antigens to identify a combination that elicits antibodies and protection in young and aged mice. While demonstrating superior immunogenicity to soluble receptor-binding domain (RBD), RBD displayed as a protein nanoparticle (RBD-NP) generated limited antibody responses. Comparison of multiple adjuvants including AddaVax, AddaS03, and AS01B in young and aged mice demonstrated that an oil-in-water emulsion containing carbohydrate fatty acid monosulphate derivative (CMS:O/W) most effectively enhanced RBD-NP-induced cross-neutralizing antibodies and protection across age groups. CMS:O/W enhanced antigen retention in the draining lymph node, induced injection site, and lymph node cytokines, with CMS inducing MyD88-dependent Th1 cytokine polarization. Furthermore, CMS and O/W synergistically induced chemokine production from human PBMCs. Overall, CMS:O/W adjuvant may enhance immunogenicity and protection of vulnerable populations against SARS-CoV-2 and other infectious pathogens.
RESUMEN
Eliciting antibodies to surface-exposed viral glycoproteins can generate protective responses that control and prevent future infections. Targeting conserved sites may reduce the likelihood of viral escape and limit the spread of related viruses with pandemic potential. Here we leverage rational immunogen design to focus humoral responses on conserved epitopes. Using glycan engineering and epitope scaffolding in boosting immunogens, we focus murine serum antibody responses to conserved receptor binding motif (RBM) and receptor binding domain (RBD) epitopes following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike imprinting. Although all engineered immunogens elicit a robust SARS-CoV-2-neutralizing serum response, RBM-focusing immunogens exhibit increased potency against related sarbecoviruses, SARS-CoV, WIV1-CoV, RaTG13-CoV, and SHC014-CoV; structural characterization of representative antibodies defines a conserved epitope. RBM-focused sera confer protection against SARS-CoV-2 challenge. Thus, RBM focusing is a promising strategy to elicit breadth across emerging sarbecoviruses without compromising SARS-CoV-2 protection. These engineering strategies are adaptable to other viral glycoproteins for targeting conserved epitopes.
Asunto(s)
COVID-19 , Proteínas del Envoltorio Viral , Animales , Ratones , Ratones Endogámicos BALB C , SARS-CoV-2 , Glicoproteína de la Espiga del CoronavirusRESUMEN
Pathogens evade host humoral responses by accumulating mutations in surface antigens. While variable, there are conserved regions that cannot mutate without compromising fitness. Antibodies targeting these conserved epitopes are often broadly protective but remain minor components of the repertoire. Rational immunogen design leverages a structural understanding of viral antigens to modulate humoral responses to favor these responses. Here, we report an epitope-enriched immunogen presenting a higher copy number of the influenza hemagglutinin (HA) receptor-binding site (RBS) epitope relative to other B cell epitopes. Immunization in a partially humanized murine model imprinted with an H1 influenza shows H1-specific serum and >99% H1-specific B cells being RBS-directed. Single B cell analyses show a genetically restricted response that structural analysis defines as RBS-directed antibodies engaging the RBS with germline-encoded contacts. These data show how epitope enrichment expands B cell responses toward conserved epitopes and advances immunogen design approaches for next-generation viral vaccines.
Asunto(s)
Vacunas contra la Influenza , Gripe Humana , Humanos , Ratones , Animales , Glicoproteínas Hemaglutininas del Virus de la Influenza/química , Anticuerpos Antivirales , Epítopos de Linfocito BRESUMEN
Global deployment of vaccines that can provide protection across several age groups is still urgently needed to end the COVID-19 pandemic, especially in low- and middle-income countries. Although vaccines against SARS-CoV-2 based on mRNA and adenoviral vector technologies have been rapidly developed, additional practical and scalable SARS-CoV-2 vaccines are required to meet global demand. Protein subunit vaccines formulated with appropriate adjuvants represent an approach to address this urgent need. The receptor binding domain (RBD) is a key target of SARS-CoV-2 neutralizing antibodies but is poorly immunogenic. We therefore compared pattern recognition receptor (PRR) agonists alone or formulated with aluminum hydroxide (AH) and benchmarked them against AS01B and AS03-like emulsion-based adjuvants for their potential to enhance RBD immunogenicity in young and aged mice. We found that an AH and CpG adjuvant formulation (AH:CpG) produced an 80-fold increase in anti-RBD neutralizing antibody titers in both age groups relative to AH alone and protected aged mice from the SARS-CoV-2 challenge. The AH:CpG-adjuvanted RBD vaccine elicited neutralizing antibodies against both wild-type SARS-CoV-2 and the B.1.351 (beta) variant at serum concentrations comparable to those induced by the licensed Pfizer-BioNTech BNT162b2 mRNA vaccine. AH:CpG induced similar cytokine and chemokine gene enrichment patterns in the draining lymph nodes of both young adult and aged mice and enhanced cytokine and chemokine production in human mononuclear cells of younger and older adults. These data support further development of AH:CpG-adjuvanted RBD as an affordable vaccine that may be effective across multiple age groups.
Asunto(s)
Hidróxido de Aluminio , COVID-19 , Anciano , Animales , Anticuerpos Neutralizantes , Anticuerpos Antivirales , Vacuna BNT162 , Vacunas contra la COVID-19 , Humanos , Ratones , Pandemias , SARS-CoV-2 , Glicoproteína de la Espiga del Coronavirus , Vacunas Sintéticas , Vacunas de ARNmRESUMEN
Antibody immunodominance refers to the preferential and asymmetric elicitation of antibodies against specific epitopes on a complex protein antigen. Traditional vaccination approaches for rapidly evolving pathogens have had limited success in part because of this phenomenon, as elicited antibodies preferentially target highly variable regions of antigens, and thus do not confer long lasting protection. While antibodies targeting functionally conserved epitopes have the potential to be broadly protective, they often make up a minority of the overall repertoire. Here, we discuss recent protein engineering strategies used to favorably alter patterns of immunodominance, and selectively focus antibody responses toward broadly protective epitopes in the pursuit of next-generation vaccines for rapidly evolving pathogens.