Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 211
Filtrar
Filtros adicionais











Intervalo de ano
1.
JCI Insight ; 4(17)2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31484826

RESUMO

Broadly neutralizing antibodies (bNAbs) against HIV-1 are under evaluation for both prevention and therapy. HIV-1 sequence diversity observed in most HIV-infected individuals and archived variations in critical bNAb epitopes present a major challenge for the clinical application of bNAbs, as preexistent resistant viral strains can emerge, resulting in bNAb failure to control HIV. In order to identify viral resistance in patients prior to antibody therapy and to guide the selection of effective bNAb combination regimens, we developed what we believe to be a novel Bayesian machine-learning model that uses HIV-1 envelope protein sequences and foremost approximated glycan occupancy information as variables to quantitatively predict the half-maximal inhibitory concentrations (IC50) of 126 neutralizing antibodies against a variety of cross clade viruses. We then applied this model to peripheral blood mononuclear cell-derived proviral Env sequences from 25 HIV-1-infected individuals mapping the landscape of neutralization resistance within each individual's reservoir and determined the predicted ideal bNAb combination to achieve 100% neutralization at IC50 values <1 µg/ml. Furthermore, predicted cellular viral reservoir neutralization signatures of individuals before an analytical antiretroviral treatment interruption were consistent with the measured neutralization susceptibilities of the respective plasma rebound viruses, validating our model as a potentially novel tool to facilitate the advancement of bNAbs into the clinic.

2.
Cell ; 178(6): 1313-1328.e13, 2019 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-31491384

RESUMO

Emerging evidence indicates a central role for the microbiome in immunity. However, causal evidence in humans is sparse. Here, we administered broad-spectrum antibiotics to healthy adults prior and subsequent to seasonal influenza vaccination. Despite a 10,000-fold reduction in gut bacterial load and long-lasting diminution in bacterial diversity, antibody responses were not significantly affected. However, in a second trial of subjects with low pre-existing antibody titers, there was significant impairment in H1N1-specific neutralization and binding IgG1 and IgA responses. In addition, in both studies antibiotics treatment resulted in (1) enhanced inflammatory signatures (including AP-1/NR4A expression), observed previously in the elderly, and increased dendritic cell activation; (2) divergent metabolic trajectories, with a 1,000-fold reduction in serum secondary bile acids, which was highly correlated with AP-1/NR4A signaling and inflammasome activation. Multi-omics integration revealed significant associations between bacterial species and metabolic phenotypes, highlighting a key role for the microbiome in modulating human immunity.

3.
Immunity ; 2019 Aug 23.
Artigo em Inglês | MEDLINE | ID: mdl-31492649

RESUMO

Immunity that controls parasitemia and inflammation during Plasmodium falciparum (Pf) malaria can be acquired with repeated infections. A limited understanding of this complex immune response impedes the development of vaccines and adjunctive therapies. We conducted a prospective systems biology study of children who differed in their ability to control parasitemia and fever following Pf infection. By integrating whole-blood transcriptomics, flow-cytometric analysis, and plasma cytokine and antibody profiles, we demonstrate that a pre-infection signature of B cell enrichment, upregulation of T helper type 1 (Th1) and Th2 cell-associated pathways, including interferon responses, and p53 activation associated with control of malarial fever and coordinated with Pf-specific immunoglobulin G (IgG) and Fc receptor activation to control parasitemia. Our hypothesis-generating approach identified host molecules that may contribute to differential clinical outcomes during Pf infection. As a proof of concept, we have shown that enhanced p53 expression in monocytes attenuated Plasmodium-induced inflammation and predicted protection from fever.

4.
Sci Transl Med ; 11(507)2019 Aug 28.
Artigo em Inglês | MEDLINE | ID: mdl-31462510

RESUMO

Current HIV vaccines are only partially efficacious, presenting an opportunity to identify correlates of protection and, thereby, potential insight into mechanisms that prevent HIV acquisition. Two independent preclinical challenge studies in nonhuman primates (NHPs) previously showed partial efficacy of a mosaic adenovirus 26 (Ad26)-based HIV-1 vaccine candidate. To investigate the basis of this protection, we performed whole transcriptomics profiling by RNA sequencing (RNA-seq) in sorted lymphocytes from peripheral blood samples taken during these studies at different time points after vaccination but before challenge. We observed a transcriptional signature in B cells that associated with protection from acquisition of simian immunodeficiency virus (SIV) or the simian-human immunodeficiency virus (SHIV) in both studies. Strong antibody responses were elicited, and genes from the signature for which expression was enriched specifically associated with higher magnitude of functional antibody responses. The same gene expression signature also associated with protection in RV144 in the only human HIV vaccine trial to date that has shown efficacy and in two additional NHP studies that evaluated similar canarypox-based vaccine regimens. A composite gene expression score derived from the gene signature was one of the top-ranked correlates of protection in the NHP vaccine studies. This study aims to bridge preclinical and clinical data with the identification of a gene signature in B cells that is associated with protection from SIV and HIV infection by providing a new approach for evaluating future vaccine candidates.

5.
Front Immunol ; 10: 1851, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31456799

RESUMO

Antibodies serve as the primary correlate of protection following most clinically approved vaccines and are thought to confer protection in part through their ability to block (neutralize) infection. Increasingly, studies have shown that beyond their blocking activities, the ability of antibodies to leverage the innate immune response may serve a vital role in protection from infection. Specifically, antibodies can drive phagocytosis, complement activation, and cellular cytotoxicity by interacting with Fc-receptors found on all innate immune cells. Measuring the capacity of antibodies to induce these functions has become critical for the identification of correlates of protection in large-scale vaccine trials. Therefore, there is a growing need to develop robust, high throughput assays able to interrogate the functional capacity of innate immune recruiting antibodies. However, in many instances, only small sample volumes are available. Nevertheless, profiling antibody functions across many pathogen-associated antigens or across global intra-pathogen variants is in high demand, making sample sparing approaches to perform this antibody evaluation critical. Here we describe the development of an approach to interrogate the functional activity of antibodies in serum against up to 5 antigen targets simultaneously. A single bead-based cellular assay was adapted to accommodate 5 different fluorescently colored beads, allowing for the concurrent investigation of antibody responses directed against multiple antigens in a single well. The multiplexed assay was as sensitive, specific, and accurate as the single antigen assay and robustly able to assess functional differences mediated by antibodies across different samples. These findings show multiplexing allows for accurate and more efficient analysis of antibody-mediated effector profiles.

6.
J Infect Dis ; 2019 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-31301137

RESUMO

BACKGROUND: Monoclonal antibodies can mediate protection against Ebola virus (EBOV) infection through direct neutralization as well as through the recruitment of innate immune effector functions. However, the antibody functional response following survival of acute EBOV disease has not been well characterized. METHODS: Serum antibodies from EVD survivors from Sierra Leone were profiled to capture variation in overall subclass/isotype abundance, neutralizing activity, and innate immune effector functions. RESULTS: Antibodies from EVD survivors exhibit robust innate immune effector functions, mediated primarily by IgG1 and IgA1. CONCLUSIONS: Development of functional antibodies follows survival of acute EVD.

7.
J Immunol Methods ; 473: 112630, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31301278

RESUMO

The complement system plays a critical role in innate immune defense against pathogens, both via non-specific direct pathogen recognition and killing or via antigen-specific indirect recruitment by complement fixing antibodies. While various assays for measuring complement activation have been developed, few provide a high-throughput, sample-sparing approach to interrogate the qualitative differences in the ability of antibodies to drive complement activation. Here we present a high-throughput, sample-sparing, bead-based assay to evaluate antigen-specific antibody-dependent complement activation against nearly any antigen. Optimization of buffer composition, kinetics of immune complex formation, as well as complement source all contribute critically to the development of a robust, highly flexible and high-throughput approach to analyze antibody-dependent complement deposition (ADCD). Thus, the optimized bead-based, antigen-specific assay represents a simple, highly adaptable platform to profile antibody-dependent complement activation across pathogens and diseases.

8.
J Exp Med ; 2019 Jul 23.
Artigo em Inglês | MEDLINE | ID: mdl-31337735

RESUMO

Despite causing outbreaks of fever and arthritis in multiple countries, no countermeasures exist against Mayaro virus (MAYV), an emerging mosquito-transmitted alphavirus. We generated 18 neutralizing mAbs against MAYV, 11 of which had "elite" activity that inhibited infection with EC50 values of <10 ng/ml. Antibodies with the greatest inhibitory capacity in cell culture mapped to epitopes near the fusion peptide of E1 and in domain B of the E2 glycoproteins. Unexpectedly, many of the elite neutralizing mAbs failed to prevent MAYV infection and disease in vivo. Instead, the most protective mAbs bound viral antigen on the cell surface with high avidity and promoted specific Fc effector functions, including phagocytosis by neutrophils and monocytes. In subclass switching studies, murine IgG2a and humanized IgG1 mAb variants controlled infection better than murine IgG1 and humanized IgG1-N297Q variants. An optimally protective antibody response to MAYV and possibly other alphaviruses may require tandem virus neutralization by the Fab moiety and effector functions of the Fc region.

9.
Cell ; 178(1): 190-201.e11, 2019 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-31204101

RESUMO

The placental transfer of maternal IgG is critical for infant protection against infectious pathogens. However, factors that modulate the placental transfer of IgG remain largely undefined. HIV-infected women have impaired placental IgG transfer, presenting a unique "disruption model" to define factors that modulate placental IgG transfer. We measured the placental transfer efficiency of maternal HIV and pathogen-specific IgG in US and Malawian HIV-infected mothers and their HIV-exposed uninfected and infected infants. We examined the role of maternal HIV disease progression, infant factors, placental Fc receptor expression, IgG subclass, and glycan signatures and their association with placental IgG transfer efficiency. Maternal IgG characteristics, such as binding to placentally expressed Fc receptors FcγRIIa and FcγRIIIa, and Fc region glycan profiles were associated with placental IgG transfer efficiency. Our findings suggest that Fc region characteristics modulate the selective placental transfer of IgG, with implications for maternal vaccine design and infant health.

10.
Proc Natl Acad Sci U S A ; 116(27): 13474-13479, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31213541

RESUMO

A major obstacle to vaccination against antigenically variable viruses is skewing of antibody responses to variable immunodominant epitopes. For influenza virus hemagglutinin (HA), the immunodominance of the variable head impairs responses to the highly conserved stem. Here, we show that head immunodominance depends on the physical attachment of head to stem. Stem immunogenicity is enhanced by immunizing with stem-only constructs or by increasing local HA concentration in the draining lymph node. Surprisingly, coimmunization of full-length HA and stem alters stem-antibody class switching. Our findings delineate strategies for overcoming immunodominance, with important implications for human vaccination.

11.
Nat Med ; 25(7): 1175, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31222179

RESUMO

In the version of this article originally published, there was an error in the abstract. The word disease should not have been included in the sentence "These individuals were highly exposed to Mtb but tested negative disease by IFN-γ release assay and tuberculin skin test, 'resisting' development of classic LTBI". The sentence should have been "These individuals were highly exposed to Mtb but tested negative by IFN-γ release assay and tuberculin skin test, 'resisting' development of classic LTBI." The error has been corrected in the HTML and PDF versions of this article.

12.
Cell ; 178(1): 202-215.e14, 2019 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-31204102

RESUMO

Despite the worldwide success of vaccination, newborns remain vulnerable to infections. While neonatal vaccination has been hampered by maternal antibody-mediated dampening of immune responses, enhanced regulatory and tolerogenic mechanisms, and immune system immaturity, maternal pre-natal immunization aims to boost neonatal immunity via antibody transfer to the fetus. However, emerging data suggest that antibodies are not transferred equally across the placenta. To understand this, we used systems serology to define Fc features associated with antibody transfer. The Fc-profile of neonatal and maternal antibodies differed, skewed toward natural killer (NK) cell-activating antibodies. This selective transfer was linked to digalactosylated Fc-glycans that selectively bind FcRn and FCGR3A, resulting in transfer of antibodies able to efficiently leverage innate immune cells present at birth. Given emerging data that vaccination may direct antibody glycosylation, our study provides insights for the development of next-generation maternal vaccines designed to elicit antibodies that will most effectively aid neonates.

13.
J Virol ; 93(14)2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-31043532

RESUMO

Acute HIV-1 infection is characterized by high viremia and massive depletion of CD4+ T cells throughout all tissue compartments. During this time the latent viral reservoir is established but the dynamics of memory CD4+ T cell subset development, their infectability and influence on disease progression during acute HIV-1 infection has not been carefully described. We therefore investigated the dynamics of CD4+ T cell memory populations in the RV217 (ECHO) cohort during the acute phase of infection. Interestingly, while we found only small changes in central or effector memory compartments, we observed a profound expansion of stem cell-like memory CD4+ T cells (SCM) (2.7-fold; P < 0.0001). Furthermore, we demonstrated that the HIV-1 integration and replication preferentially take place in highly differentiated CD4+ T cells such as transitional memory (TM) and effector memory (EM) CD4+ T cells, while naive and less mature memory cells prove to be more resistant. Despite the relatively low frequency of productively infected SCM, we suggest that their quiescent phenotype, increased susceptibility to HIV-1 integration compared to naive cells and extensive expansion make them one of the key players in establishment and persistence of the HIV-1 reservoir. Moreover, the expansion of SCM in acute HIV-1 infection was a result of Fas upregulation on the surface of naive CD4+ T cells. Interestingly, the upregulation of Fas receptor and expansion of SCM in acute HIV-1 infection was associated with the early viral set point and disease progression (rho = 0.47, P = 0.02, and rho = 0.42, P = 0.041, respectively). Taken together, our data demonstrate an expansion of SCM during early acute HIV-1 infection which is associated with disease outcome.IMPORTANCE Understanding the immunopathology of acute HIV-1 infection will help to develop eradication strategies. We demonstrate here that a CD4+ T cell memory subset expands during acute HIV-1 infection, which is associated with disease progression.

14.
Mol Syst Biol ; 15(5): e8747, 2019 May 02.
Artigo em Inglês | MEDLINE | ID: mdl-31048360

RESUMO

Characterizing the antigen-binding and innate immune-recruiting properties of the humoral response offers the chance to obtain deeper insights into mechanisms of protection than revealed by measuring only overall antibody titer. Here, a high-throughput, multiplexed Fab-Fc Array was employed to profile rhesus macaques vaccinated with a gp120-CD4 fusion protein in combination with different genetically encoded adjuvants, and subsequently subjected to multiple heterologous simian immunodeficiency virus (SIV) challenges. Systems analyses modeling protection and adjuvant differences using Fab-Fc Array measurements revealed a set of correlates yielding strong and robust predictive performance, while models based on measurements of response magnitude alone exhibited significantly inferior performance. At the same time, rendering Fab-Fc measurements mathematically independent of titer had relatively little impact on predictive performance. Similar analyses for a distinct SIV vaccine study also showed that Fab-Fc measurements performed significantly better than titer. These results suggest that predictive modeling with measurements of antibody properties can provide detailed correlates with robust predictive power, suggest directions for vaccine improvement, and potentially enable discovery of mechanistic associations.

15.
Front Immunol ; 10: 996, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31143177

RESUMO

Tuberculosis infects one quarter of the world's population and is the leading cause of death by a single infectious agent, responsible for a reported 1.3 million deaths in 2017. While Mycobacterium tuberculosis is treatable with antibiotic therapy, the increased prevalence of drug resistance, coupled with the variable efficacy of the only widely approved vaccine, has highlighted the need for creative approaches to therapeutic and vaccine development. Historically, a productive immune response to M. tuberculosis has been thought to be nearly entirely cell-mediated, with humoral immunity being largely dismissed. However, in this review, we will discuss the historical skepticism surrounding the role of the humoral immune response to M. tuberculosis, and examine more recent evidence suggesting that antibodies may play a valuable role in host defense against the pathogen. Despite the amount of data portraying antibodies in a negative light, emerging data have begun to highlight the unexpected role of antibodies in M. tuberculosis control. Specifically, it has become clear that antibody features of both the variable and constant domain (Fc) ultimately determine the extent to which antibodies modulate disease. Thus, a more precise definition of the antigen-binding and innate immune recruiting functions of antibodies that contribute to M. tuberculosis restriction, are sure to help guide the development of next-generation therapeutics and vaccines to curb this global epidemic.

16.
J Immunol Methods ; 471: 46-56, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31132351

RESUMO

Neutrophils, the most abundant white blood cell, play a critical role in anti-pathogen immunity via phagocytic clearance, secretion of enzymes and immunomodulators, and the release of extracellular traps. Neutrophils non-specifically sense infection through an array of innate immune receptors and inflammatory sensors, but are also able to respond in a pathogen/antigen-specific manner when leveraged by antibodies via Fc-receptors. Among neutrophil functions, antibody-dependent neutrophil phagocytosis (ADNP) results in antibody-mediated opsonization, enabling neutrophils to sense and respond to infection in a pathogen-appropriate manner. Here, we describe a high-throughput flow cytometric approach to effectively visualize and quantify ADNP and its downstream consequences. The assay is easily adaptable, supporting both the use of purified neutrophils or white blood cells, the use of purified Ig or serum, and the broad utility of any target antigen. Thus, this ADNP assay represents a high-throughput platform for the in-depth characterization of neutrophil function.

17.
Nat Med ; 25(6): 977-987, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31110348

RESUMO

Exposure to Mycobacterium tuberculosis (Mtb) results in heterogeneous clinical outcomes including primary progressive tuberculosis and latent Mtb infection (LTBI). Mtb infection is identified using the tuberculin skin test and interferon-γ (IFN-γ) release assay IGRA, and a positive result may prompt chemoprophylaxis to prevent progression to tuberculosis. In the present study, we report on a cohort of Ugandan individuals who were household contacts of patients with TB. These individuals were highly exposed to Mtb but tested negative disease by IFN-γ release assay and tuberculin skin test, 'resisting' development of classic LTBI. We show that 'resisters' possess IgM, class-switched IgG antibody responses and non-IFN-γ T cell responses to the Mtb-specific proteins ESAT6 and CFP10, immunologic evidence of exposure to Mtb. Compared to subjects with classic LTBI, 'resisters' display enhanced antibody avidity and distinct Mtb-specific IgG Fc profiles. These data reveal a distinctive adaptive immune profile among Mtb-exposed subjects, supporting an expanded definition of the host response to Mtb exposure, with implications for public health and the design of clinical trials.


Assuntos
Tuberculose Latente/imunologia , Mycobacterium tuberculosis/imunologia , Tuberculose/imunologia , Adulto , Anticorpos Antibacterianos/sangue , Antígenos de Bactérias/imunologia , Biomarcadores/metabolismo , Linfócitos T CD4-Positivos/imunologia , Criança , Estudos de Coortes , Feminino , Humanos , Interferon gama/imunologia , Testes de Liberação de Interferon-gama , Masculino , Teste Tuberculínico , Uganda , Adulto Jovem
18.
Front Immunol ; 10: 440, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30949165

RESUMO

While neutralizing antibody titers measured by hemagglutination inhibition have been proposed as a correlate of protection following influenza vaccination, neutralization alone is a modest predictor of protection against seasonal influenza. Instead, emerging data point to a critical role for additional extra-neutralizing functions of antibodies in protection from infection. Specifically, beyond binding and neutralization, antibodies mediate a variety of additional immune functions via their ability to recruit and deploy innate immune effector function. Along these lines, antibody-dependent cellular cytotoxicity, antibody-mediated macrophage phagocytosis and activation, antibody-driven neutrophil activation, antibody-dependent complement deposition, and non-classical Fc-receptor antibody trafficking have all been implicated in protection from influenza infection. However, the precise mechanism(s) by which the immune system actively tunes antibody functionality to drive protective immunity has been poorly characterized. Here we review the data related to Fc-effector functional protection from influenza and discuss prospects to leverage this humoral immune activity for the development of a universal influenza vaccine.

19.
PLoS Comput Biol ; 15(4): e1006952, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30933973

RESUMO

The broadly neutralizing antibody (bnAb) VRC01 is being evaluated for its efficacy to prevent HIV-1 infection in the Antibody Mediated Prevention (AMP) trials. A secondary objective of AMP utilizes sieve analysis to investigate how VRC01 prevention efficacy (PE) varies with HIV-1 envelope (Env) amino acid (AA) sequence features. An exhaustive analysis that tests how PE depends on every AA feature with sufficient variation would have low statistical power. To design an adequately powered primary sieve analysis for AMP, we modeled VRC01 neutralization as a function of Env AA sequence features of 611 HIV-1 gp160 pseudoviruses from the CATNAP database, with objectives: (1) to develop models that best predict the neutralization readouts; and (2) to rank AA features by their predictive importance with classification and regression methods. The dataset was split in half, and machine learning algorithms were applied to each half, each analyzed separately using cross-validation and hold-out validation. We selected Super Learner, a nonparametric ensemble-based cross-validated learning method, for advancement to the primary sieve analysis. This method predicted the dichotomous resistance outcome of whether the IC50 neutralization titer of VRC01 for a given Env pseudovirus is right-censored (indicating resistance) with an average validated AUC of 0.868 across the two hold-out datasets. Quantitative log IC50 was predicted with an average validated R2 of 0.355. Features predicting neutralization sensitivity or resistance included 26 surface-accessible residues in the VRC01 and CD4 binding footprints, the length of gp120, the length of Env, the number of cysteines in gp120, the number of cysteines in Env, and 4 potential N-linked glycosylation sites; the top features will be advanced to the primary sieve analysis. This modeling framework may also inform the study of VRC01 in the treatment of HIV-infected persons.


Assuntos
Anticorpos Monoclonais/farmacologia , Proteína gp160 do Envelope de HIV/genética , Proteína gp160 do Envelope de HIV/imunologia , Sequência de Aminoácidos , Anticorpos Monoclonais/genética , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Sítios de Ligação , Antígenos CD4 , Simulação por Computador , Previsões/métodos , Glicosilação , Anticorpos Anti-HIV/imunologia , Infecções por HIV/virologia , HIV-1/imunologia , Humanos , Ligação Proteica
20.
Curr HIV/AIDS Rep ; 16(2): 169-179, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-30903381

RESUMO

PURPOSE OF REVIEW: The design of an HIV vaccine remains an elusive but top priority. Data from the non-human primate model and the first moderately protective HIV vaccine trial (RV144) point to a role for qualitative changes in humoral immune functions in protection from infection. Here, we review the current understanding of the antibody response throughout HIV infection, the known correlates of protection, and current strategies to manipulate antibodies to put an end to the epidemic. RECENT FINDINGS: Recent studies point to innate immune-recruiting antibody function in preventing infection as well as controlling viremia following infection. These data have begun to inform next-generation design of HIV vaccines and antibody therapies by uncovering new viral targets and antibody architectures to improve potency and breadth. Emerging data illustrate a role for innate immune recruiting-antibodies in conferring protection against HIV infection as well as promoting viral control and clearance, offering an unprecedented opportunity to modulate and improve antibody function to fight HIV more effectively.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA