Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 4.227
Filtrar
1.
Ann Agric Environ Med ; 26(3): 392-395, 2019 Sep 19.
Artigo em Inglês | MEDLINE | ID: mdl-31559791

RESUMO

Existing research for using the protective antigen (PA) of Bacillus anthracis as a vaccine component shows that protection against anthrax may be obtained using fragments of this protein. The aim of the research is to check whether the selected protein fragment of the protective antigen (domain 4) encoded by an appropriate nucleotide sequence of gene pag of B. anthracis, was expressed in the bacterial system of E. coli. In order to examine the selected sequence of the pag gene, a PCR reaction and a highly effective TOPO cloning strategy were used, followed by purification of the recombinant proteins and their detection by a western-blot method. In the planning of the PA4 antigen expression a higher level of effectiveness in production of small protein - domain 4 - was anticipated. As a result, the 139 amino acids protein fragment of B. anthracis PA (domain 4) was isolated. The research may have found the basis for in vivo research aimed at finding potential anthrax vaccine components.


Assuntos
Vacinas contra Antraz/imunologia , Antraz/microbiologia , Antígenos de Bactérias/imunologia , Bacillus anthracis/imunologia , Toxinas Bacterianas/imunologia , Animais , Antraz/imunologia , Antraz/prevenção & controle , Vacinas contra Antraz/administração & dosagem , Vacinas contra Antraz/genética , Vacinas contra Antraz/isolamento & purificação , Anticorpos Antibacterianos/imunologia , Anticorpos Neutralizantes/imunologia , Antígenos de Bactérias/administração & dosagem , Antígenos de Bactérias/genética , Antígenos de Bactérias/isolamento & purificação , Bacillus anthracis/química , Bacillus anthracis/genética , Toxinas Bacterianas/administração & dosagem , Toxinas Bacterianas/genética , Toxinas Bacterianas/isolamento & purificação , Western Blotting , Escherichia coli/genética , Escherichia coli/metabolismo , Expressão Gênica , Humanos , Imunização , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Domínios Proteicos
2.
Mem Inst Oswaldo Cruz ; 114: e190098, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31411310

RESUMO

BACKGROUND: Dengue virus (DENV) has circulated in Brazil for over 30 years. During this time, one serotype has cyclically replaced the other, until recently, when all four distinct serotypes began to circulate together. Persistent circulation of DENV for long time periods makes sequential infections throughout a person's life possible. After primary DENV infection, life-long immunity is developed for the infecting serotype. Since DENV and Zika virus (ZIKV) are antigenically similar, the possibility of cross-reactions has attracted attention and has been demonstrated in vitro. OBJECTIVE: The aim of this study was to investigate whether immune-sera from DENV and ZIKV infected patients would cross-react in vitro with other Flaviviridae family members. METHODS: Cross-reaction of the studied samples with yellow fever virus (YFV), West Nile virus (WNV), Rocio virus (ROCV), Saint Louis virus (SLEV) and Ilheus virus (ILHV) has been investigated by plaque reduction neutralisation test (PRNT) and the antibody-dependent enhancement (ADE) by flow-cytometry. FINDINGS: Antibodies against ZIKV and DENV virus cross-reacted with other flaviviruses either neutralising or enhancing the infection. Thus, viral entrance into FcRFcɣRII-expressing cells were influenced by the cross-reactive antibodies. ZIKV or DENV immune sera enhanced cellular infection by WNV, ILHV, ROCV and SLEV. Finally, DENV immune sera presented higher neutralising activity for YFV and SLEV. While ZIKV immune sera neutralised WNV, ILHV and ROCV with high frequencies of positivity. MAIN CONCLUSIONS: The co-circulation of those viruses in the same area represents a risk for the development of severe infections if they spread throughout the country. Successive flavivirus infections may have an impact on disease pathogenesis, as well as on the development of safe vaccine strategies.


Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Vírus da Dengue/imunologia , Zika virus/imunologia , Reações Cruzadas/imunologia , Flavivirus/classificação , Flavivirus/imunologia , Citometria de Fluxo , Humanos , Testes de Neutralização
3.
Nat Commun ; 10(1): 2898, 2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31263112

RESUMO

The HIV-1 envelope (Env) is the target for neutralizing antibodies and exists on the surface of virions in open or closed conformations. Difficult-to-neutralize viruses (tier 2) express Env in a closed conformation antigenic for broadly neutralizing antibodies (bnAbs) but not for third variable region (V3) antibodies. Here we show that select V3 macaque antibodies elicited by Env vaccination can neutralize 26% of otherwise tier 2 HIV-1 isolates in standardized virus panels. The V3 antibodies only bound to Env in its open conformation. Thus, Envs on tier 2 viruses sample a state where the V3 loop is not in its closed conformation position. Envelope second variable region length, glycosylation sites and V3 amino acids were signatures of neutralization sensitivity. This study determined that open conformations of Env with V3 exposed are present on a subset of otherwise neutralization-resistant virions, therefore neutralization of tier 2 HIV-1 does not always indicate bnAb induction.


Assuntos
Anticorpos Anti-HIV/imunologia , Infecções por HIV/imunologia , HIV-1/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Motivos de Aminoácidos , Animais , Anticorpos Neutralizantes/imunologia , Glicosilação , Infecções por HIV/virologia , HIV-1/química , HIV-1/genética , Humanos , Macaca mulatta , Testes de Neutralização , Conformação Proteica , Produtos do Gene env do Vírus da Imunodeficiência Humana/química
4.
Nat Commun ; 10(1): 2699, 2019 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-31221976

RESUMO

Human cytomegalovirus (CMV) causes a wide array of disease to diverse populations of immune-compromised individuals. Thus, a more comprehensive understanding of how CMV enters numerous host cell types is necessary to further delineate the complex nature of CMV pathogenesis and to develop targeted therapeutics. To that end, we establish a vaccination strategy utilizing membrane vesicles derived from epithelial cells to generate a library of monoclonal antibodies (mAbs) targeting cell surface proteins in their native conformation. A high-throughput inhibition assay is employed to screen these antibodies for their ability to limit infection, and mAbs targeting CD46 are identified. In addition, a significant reduction of viral proliferation in CD46-KO epithelial cells confirms a role for CD46 function in viral dissemination. Further, we demonstrate a CD46-dependent entry pathway of virus infection in trophoblasts, but not in fibroblasts, highlighting the complexity of CMV entry and identifying CD46 as an entry factor in congenital infection.


Assuntos
Infecções por Citomegalovirus/imunologia , Citomegalovirus/imunologia , Interações Hospedeiro-Patógeno/imunologia , Proteína Cofatora de Membrana/imunologia , Internalização do Vírus , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/administração & dosagem , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/administração & dosagem , Anticorpos Antivirais/imunologia , Linhagem Celular , Infecções por Citomegalovirus/prevenção & controle , Infecções por Citomegalovirus/virologia , Células Epiteliais/imunologia , Células Epiteliais/virologia , Fibroblastos/imunologia , Fibroblastos/virologia , Técnicas de Inativação de Genes , Humanos , Proteína Cofatora de Membrana/genética , RNA Interferente Pequeno/metabolismo , Trofoblastos/imunologia , Trofoblastos/virologia , Vacinas Virais/administração & dosagem , Vacinas Virais/imunologia
5.
Arch Virol ; 164(8): 2165-2170, 2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31154511

RESUMO

Zika virus (ZIKV) circulation occurs between non-human primates (NHPs) in a sylvatic transmission cycle. To investigate evidence of flavivirus infection in NHPs in Zambia, we performed a plaque reduction neutralization test (PRNT) to quantify neutralizing antibodies. PRNT revealed that sera from NHPs (African green monkeys and baboons) exhibited neutralizing activity against ZIKV (34.4%; 33/96), whereas a PRNT for yellow fever virus using NHP sera showed no neutralization activity. ZIKV genomic RNA was not detected in splenic tissues from NHPs, suggesting that the presence of anti-ZIKV neutralizing antibodies represented resolved infections. Our evidence suggests that ZIKV is maintained in NHP reservoirs in Zambia.


Assuntos
Infecção por Zika virus/imunologia , Infecção por Zika virus/virologia , Zika virus/imunologia , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Reações Cruzadas/imunologia , Vírus da Dengue/imunologia , Infecções por Flavivirus/imunologia , Infecções por Flavivirus/virologia , Primatas , Testes Sorológicos/métodos , Zâmbia
6.
Dokl Biochem Biophys ; 485(1): 126-128, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31201631

RESUMO

We generated a novel human neutralizing human mAb RabD4 against rabies virus glycoprotein using in vitro stimulation of human peripheral B cells produced by immunized donor. The human mAb RabD4 showed a high antigen-binding activity and virus-neutralizing activity in the FAVN test with the CVS-11 rabies virus.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Vírus da Raiva/imunologia , Proteínas Virais/imunologia , Humanos
7.
Nat Commun ; 10(1): 2073, 2019 05 06.
Artigo em Inglês | MEDLINE | ID: mdl-31061402

RESUMO

Isolation of broadly neutralizing human monoclonal antibodies (HmAbs) targeting the E2 glycoprotein of Hepatitis C virus (HCV) has sparked hope for effective vaccine development. Nonetheless, escape mutations have been reported. Ideally, a potent vaccine should elicit HmAbs that target regions of E2 that are most difficult to escape. Here, aimed at addressing this challenge, we develop a predictive in-silico evolutionary model for E2 that identifies one such region, a specific antigenic domain, making it an attractive target for a robust antibody response. Specific broadly neutralizing HmAbs that appear difficult to escape from are also identified. By providing a framework for identifying vulnerable regions of E2 and for assessing the potency of specific antibodies, our results can aid the rational design of an effective prophylactic HCV vaccine.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Hepacivirus/imunologia , Hepatite C/imunologia , Proteínas do Envelope Viral/imunologia , Simulação por Computador , Desenho de Drogas , Mapeamento de Epitopos/métodos , Epitopos/genética , Epitopos/imunologia , Evolução Molecular , Hepacivirus/genética , Hepatite C/prevenção & controle , Hepatite C/virologia , Humanos , Modelos Biológicos , Proteínas do Envelope Viral/genética , Vacinas contra Hepatite Viral/imunologia
8.
Nat Commun ; 10(1): 2105, 2019 05 08.
Artigo em Inglês | MEDLINE | ID: mdl-31068578

RESUMO

The respiratory syncytial virus (RSV) F glycoprotein is a class I fusion protein that mediates viral entry and is a major target of neutralizing antibodies. Structures of prefusion forms of RSV F, as well as other class I fusion proteins, have revealed compact trimeric arrangements, yet whether these trimeric forms can transiently open remains unknown. Here, we perform structural and biochemical studies on a recently isolated antibody, CR9501, and demonstrate that it enhances the opening of prefusion-stabilized RSV F trimers. The 3.3 Å crystal structure of monomeric RSV F bound to CR9501, combined with analysis of over 25 previously determined RSV F structures, reveals a breathing motion of the prefusion conformation. We also demonstrate that full-length RSV F trimers transiently open and dissociate on the cell surface. Collectively, these findings have implications for the function of class I fusion proteins, as well as antibody prophylaxis and vaccine development for RSV.


Assuntos
Anticorpos Neutralizantes/metabolismo , Anticorpos Antivirais/metabolismo , Vírus Sincicial Respiratório Humano/fisiologia , Proteínas Virais de Fusão/metabolismo , Animais , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/química , Anticorpos Antivirais/imunologia , Linfócitos B/virologia , Cercopithecus aethiops , Simulação por Computador , Cristalografia por Raios X , Desenvolvimento de Medicamentos , Células HEK293 , Células HeLa , Humanos , Modelos Moleculares , Multimerização Proteica/fisiologia , Infecções por Vírus Respiratório Sincicial/imunologia , Infecções por Vírus Respiratório Sincicial/prevenção & controle , Infecções por Vírus Respiratório Sincicial/virologia , Vacinas contra Vírus Sincicial Respiratório/imunologia , Vírus Sincicial Respiratório Humano/isolamento & purificação , Células Vero , Proteínas Virais de Fusão/química , Proteínas Virais de Fusão/imunologia
9.
J Immunol Res ; 2019: 6491738, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31089478

RESUMO

Middle East respiratory syndrome coronavirus (MERS-CoV) first emerged in late 2012. Since its emergence, a total of 2279 patients from 27 countries have been infected across the globe according to a World Health Organization (WHO) report (Feb. 12th, 2019). Approximately 806 patients have died. The virus uses its spike proteins as adhesive factors that are proinflammatory for host entry through a specific receptor called dipeptidyl peptidase-4 (DPP4). This receptor is considered a key factor in the signaling and activation of the acquired and innate immune responses in infected patients. Using potent antigens in combination with strong adjuvants may effectively trigger the activation of specific MERS-CoV cellular responses as well as the production of neutralizing antibodies. Unfortunately, to date, there is no effective approved treatment or vaccine for MERS-CoV. Thus, there are urgent needs for the development of novel MERS-CoV therapies as well as vaccines to help minimize the spread of the virus from infected patients, thereby mitigating the risk of any potential pandemics. Our main goals are to highlight and describe the current knowledge of both the innate and adaptive immune responses to MERS-CoV and the current state of MERS-CoV vaccine development. We believe this study will increase our understanding of the mechanisms that enhance the MERS-CoV immune response and subsequently contribute to the control of MERS-CoV infections.


Assuntos
Imunidade Adaptativa , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/prevenção & controle , Imunidade Inata , Coronavírus da Síndrome Respiratória do Oriente Médio/imunologia , Vacinas Virais/imunologia , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Antivirais/uso terapêutico , Infecções por Coronavirus/tratamento farmacológico , Dipeptidil Peptidase 4/metabolismo , Humanos , Camundongos , Receptores Virais/metabolismo
10.
Nat Commun ; 10(1): 2190, 2019 05 16.
Artigo em Inglês | MEDLINE | ID: mdl-31097697

RESUMO

HIV-infected infants develop broadly neutralizing plasma responses with more rapid kinetics than adults, suggesting the ontogeny of infant responses could better inform a path to achievable vaccine targets. Here we reconstruct the developmental lineage of BF520.1, an infant-derived HIV-specific broadly neutralizing antibody (bnAb), using computational methods developed specifically for this purpose. We find that the BF520.1 inferred naive precursor binds HIV Env. We also show that heterologous cross-clade neutralizing activity evolved in the infant within six months of infection and that, ultimately, only 2% SHM is needed to achieve the full breadth of the mature antibody. Mutagenesis and structural analyses reveal that, for this infant bnAb, substitutions in the kappa chain were critical for activity, particularly in CDRL1. Overall, the developmental pathway of this infant antibody includes features distinct from adult antibodies, including several that may be amenable to better vaccine responses.


Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , Infecções por HIV/prevenção & controle , HIV-1/imunologia , Cadeias kappa de Imunoglobulina/imunologia , Vacinas contra a AIDS/imunologia , Fatores Etários , Anticorpos Neutralizantes/genética , Anticorpos Neutralizantes/isolamento & purificação , Anticorpos Neutralizantes/metabolismo , Biologia Computacional/métodos , Reações Cruzadas/imunologia , Desenho de Drogas , Anticorpos Anti-HIV/genética , Anticorpos Anti-HIV/isolamento & purificação , Anticorpos Anti-HIV/metabolismo , Infecções por HIV/sangue , Infecções por HIV/imunologia , Infecções por HIV/virologia , Humanos , Cadeias kappa de Imunoglobulina/genética , Cadeias kappa de Imunoglobulina/metabolismo , Lactente , Leucócitos Mononucleares , Mutagênese , Análise de Sequência de DNA , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia
11.
Nat Commun ; 10(1): 2355, 2019 05 29.
Artigo em Inglês | MEDLINE | ID: mdl-31142746

RESUMO

Stabilized HIV-1 envelope glycoproteins (Env) that resemble the native Env are utilized in vaccination strategies aimed at inducing broadly neutralizing antibodies (bNAbs). To limit the exposure of rare isolate-specific antigenic residues/determinants we generated a SOSIP trimer based on a consensus sequence of all HIV-1 group M isolates (ConM). The ConM trimer displays the epitopes of most known bNAbs and several germline bNAb precursors. The crystal structure of the ConM trimer at 3.9 Å resolution resembles that of the native Env trimer and its antigenic surface displays few rare residues. The ConM trimer elicits strong NAb responses against the autologous virus in rabbits and macaques that are significantly enhanced when it is presented on ferritin nanoparticles. The dominant NAb specificity is directed against an epitope at or close to the trimer apex. Immunogens based on consensus sequences might have utility in engineering vaccines against HIV-1 and other viruses.


Assuntos
Vacinas contra a AIDS/imunologia , Anticorpos Neutralizantes/imunologia , Epitopos/imunologia , Anticorpos Anti-HIV/imunologia , HIV-1/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Animais , Sequência Consenso , Macaca , Multimerização Proteica , Coelhos
12.
PLoS Comput Biol ; 15(4): e1006954, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-30970017

RESUMO

HIV is a highly mutable virus for which all attempts to develop a vaccine have been unsuccessful. Nevertheless, few long-infected patients develop antibodies, called broadly neutralizing antibodies (bnAbs), that have a high breadth and can neutralize multiple variants of the virus. This suggests that a universal HIV vaccine should be possible. A measure of the efficacy of a HIV vaccine is the neutralization breadth of the antibodies it generates. The breadth is defined as the fraction of viruses in the Seaman panel that are neutralized by the antibody. Experimentally the neutralization ability is measured as the half maximal inhibitory concentration of the antibody (IC50). To avoid such time-consuming experimental measurements, we developed a computational approach to estimate the IC50 and use it to determine the antibody breadth. Given that no direct method exists for calculating IC50 values, we resort to a combination of atomistic modeling and machine learning. For each antibody/virus complex, an all-atoms model is built using the amino acid sequence and a known structure of a related complex. Then a series of descriptors are derived from the atomistic models, and these are used to train a Multi-Layer Perceptron (an Artificial Neural Network) to predict the value of the IC50 (by regression), or if the antibody binds or not to the virus (by classification). The neural networks are trained by use of experimental IC50 values collected in the CATNAP database. The computed breadths obtained by regression and classification are reported and the importance of having some related information in the data set for obtaining accurate predictions is analyzed. This approach is expected to prove useful for the design of HIV bnAbs, where the computation of the potency must be accompanied by a computation of the breadth, and for evaluating the efficiency of potential vaccination schemes developed through modeling and simulation.


Assuntos
Biologia Computacional/métodos , Anticorpos Anti-HIV/classificação , Anticorpos Anti-HIV/imunologia , Vacinas contra a AIDS/imunologia , Sequência de Aminoácidos , Anticorpos Neutralizantes/genética , Anticorpos Neutralizantes/imunologia , Antígenos CD4/imunologia , Contagem de Linfócito CD4/métodos , Epitopos/imunologia , Anticorpos Anti-HIV/genética , Infecções por HIV/virologia , HIV-1/imunologia , Humanos , Concentração Inibidora 50 , Aprendizado de Máquina
13.
Nat Commun ; 10(1): 1953, 2019 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-31028254

RESUMO

Malaria vaccine design and prioritization has been hindered by the lack of a mechanistic correlate of protection. We previously demonstrated a strong association between protection and merozoite-neutralizing antibody responses following vaccination of non-human primates against Plasmodium falciparum reticulocyte binding protein homolog 5 (PfRH5). Here, we test the mechanism of protection. Using mutant human IgG1 Fc regions engineered not to engage complement or FcR-dependent effector mechanisms, we produce merozoite-neutralizing and non-neutralizing anti-PfRH5 chimeric monoclonal antibodies (mAbs) and perform a passive transfer-P. falciparum challenge study in Aotus nancymaae monkeys. At the highest dose tested, 6/6 animals given the neutralizing PfRH5-binding mAb c2AC7 survive the challenge without treatment, compared to 0/6 animals given non-neutralizing PfRH5-binding mAb c4BA7 and 0/6 animals given an isotype control mAb. Our results address the controversy regarding whether merozoite-neutralizing antibody can cause protection against P. falciparum blood-stage infections, and highlight the quantitative challenge of achieving such protection.


Assuntos
Malária Falciparum/imunologia , Malária Falciparum/prevenção & controle , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Neutralizantes/uso terapêutico , Anticorpos Antiprotozoários/imunologia , Humanos , Imunoglobulina G/genética , Imunoglobulina G/metabolismo , Vacinas Antimaláricas/uso terapêutico , Malária Falciparum/metabolismo , Plasmodium falciparum/imunologia , Plasmodium falciparum/patogenicidade , Primatas
14.
Nat Commun ; 10(1): 1788, 2019 04 17.
Artigo em Inglês | MEDLINE | ID: mdl-30996276

RESUMO

Three Ebolavirus genus viruses cause lethal disease and lack targeted therapeutics: Ebola virus, Sudan virus and Bundibugyo virus. Monoclonal antibody (mAb) cocktails against the surface glycoprotein (GP) present a potential therapeutic strategy. Here we report two crystal structures of the antibody BDBV223, alone and complexed with its GP2 stalk epitope, an interesting site for therapeutic/vaccine design due to its high sequence conservation among ebolaviruses. BDBV223, identified in a human survivor of Bundibugyo virus disease, neutralizes both Bundibugyo virus and Ebola virus, but not Sudan virus. Importantly, the structure suggests that BDBV223 binding interferes with both the trimeric bundle assembly of GP and the viral membrane by stabilizing a conformation in which the monomers are separated by GP lifting or bending. Targeted mutagenesis of BDBV223 to enhance SUDV GP recognition indicates that additional determinants of antibody binding likely lie outside the visualized interactions, and perhaps involve quaternary assembly or membrane-interacting regions.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Ebolavirus/efeitos dos fármacos , Doença pelo Vírus Ebola/imunologia , Anticorpos Monoclonais/química , Anticorpos Monoclonais/isolamento & purificação , Anticorpos Monoclonais/metabolismo , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/isolamento & purificação , Anticorpos Neutralizantes/metabolismo , Anticorpos Antivirais/química , Anticorpos Antivirais/isolamento & purificação , Anticorpos Antivirais/metabolismo , Reações Cruzadas/imunologia , Cristalografia por Raios X , Ebolavirus/imunologia , Epitopos/química , Epitopos/imunologia , Doença pelo Vírus Ebola/sangue , Doença pelo Vírus Ebola/virologia , Humanos , Hibridomas , Mutagênese , Sobreviventes , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/imunologia , Proteínas do Envelope Viral/metabolismo
15.
Nat Microbiol ; 4(7): 1231-1241, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-30936489

RESUMO

Rift Valley fever virus (RVFV) is a mosquito-borne pathogen that causes substantial morbidity and mortality in livestock and humans. To date, there are no licensed human vaccines or therapeutics available. Here, we report the isolation of monoclonal antibodies from a convalescent patient, targeting the RVFV envelope proteins Gn and Gc. The Gn-specific monoclonal antibodies exhibited much higher neutralizing activities in vitro and protection efficacies in mice against RVFV infection, compared to the Gc-specific monoclonal antibodies. The Gn monoclonal antibodies were found to interfere with soluble Gn binding to cells and prevent infection by blocking the attachment of virions to host cells. Structural analysis of Gn complexed with four Gn-specific monoclonal antibodies resulted in the definition of three antigenic patches (A, B and C) on Gn domain I. Both patches A and B are major neutralizing epitopes. Our results highlight the potential of antibody-based therapeutics and provide a structure-based rationale for designing vaccines against RVFV.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Febre do Vale de Rift/prevenção & controle , Vírus da Febre do Vale do Rift/imunologia , Animais , Anticorpos Monoclonais/administração & dosagem , Anticorpos Neutralizantes/administração & dosagem , Anticorpos Antivirais/administração & dosagem , Cercopithecus aethiops , Cristalografia por Raios X , Epitopos , Feminino , Humanos , Camundongos Endogâmicos BALB C , Testes de Neutralização , Domínios Proteicos , Febre do Vale de Rift/imunologia , Células Vero , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/imunologia , Proteínas do Envelope Viral/metabolismo , Ligação Viral
16.
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
17.
Virol Sin ; 34(2): 168-174, 2019 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-31020573

RESUMO

As we know more about Zika virus (ZIKV), as well as its linkage to birth defects (microcephaly) and autoimmune neurological syndromes, we realize the importance of developing an efficient vaccine against it. Zika virus disease has affected many countries and is becoming a major public health concern. To deal with the infection of ZIKV, plenty of experiments have been done on selection of neutralizing antibodies that can target the envelope (E) protein on the surface of the virion. However, the existence of antibody-dependent enhancement (ADE) effect might limit the use of them as therapeutic candidates. In this review, we classify the neutralizing antibodies against ZIKV based on the epitopes and summarize the resolved structural information on antibody/antigen complex from X-ray crystallography and cryo-electron microscopy (cryo-EM), which might be useful for further development of potent neutralizing antibodies and vaccines toward clinical use.


Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Proteínas do Envelope Viral/química , Proteínas do Envelope Viral/imunologia , Zika virus/imunologia , Animais , Complexo Antígeno-Anticorpo/química , Complexo Antígeno-Anticorpo/ultraestrutura , Microscopia Crioeletrônica , Cristalografia por Raios X , Epitopos/imunologia , Humanos , Camundongos
18.
Emerg Microbes Infect ; 8(1): 516-530, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30938227

RESUMO

The Middle-East respiratory syndrome coronavirus (MERS-CoV) is a zoonotic virus that causes severe and often fatal respiratory disease in humans. Efforts to develop antibody-based therapies have focused on neutralizing antibodies that target the receptor binding domain of the viral spike protein thereby blocking receptor binding. Here, we developed a set of human monoclonal antibodies that target functionally distinct domains of the MERS-CoV spike protein. These antibodies belong to six distinct epitope groups and interfere with the three critical entry functions of the MERS-CoV spike protein: sialic acid binding, receptor binding and membrane fusion. Passive immunization with potently as well as with poorly neutralizing antibodies protected mice from lethal MERS-CoV challenge. Collectively, these antibodies offer new ways to gain humoral protection in humans against the emerging MERS-CoV by targeting different spike protein epitopes and functions.


Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Antivirais/imunologia , Infecções por Coronavirus/prevenção & controle , Coronavírus da Síndrome Respiratória do Oriente Médio/imunologia , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/imunologia , Animais , Anticorpos Neutralizantes/imunologia , Infecções por Coronavirus/genética , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/virologia , Epitopos/química , Epitopos/genética , Epitopos/imunologia , Humanos , Imunização Passiva , Camundongos , Coronavírus da Síndrome Respiratória do Oriente Médio/química , Coronavírus da Síndrome Respiratória do Oriente Médio/genética , Domínios Proteicos , Receptores Virais/genética , Receptores Virais/imunologia , Glicoproteína da Espícula de Coronavírus/genética
19.
J Immunol Res ; 2019: 9804584, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31019982

RESUMO

The design of immunogens susceptible to elicit potent and broadly neutralizing antibodies against the human immunodeficiency virus type 1 (HIV-1) remains a veritable challenge in the course of vaccine development. Viral envelope proteins adopt different conformational states during the entry process, allowing the presentation of transient neutralizing epitopes. We focused on the highly conserved 3S motif of gp41, which is exposed to the surface envelope in its trimeric prefusion state. Vaccination with a W614A-modified 3S peptide induces in animals neutralizing anti-HIV-1 antibodies among which we selected clone F8. We used F8 as bait to select for W614A-3S phage-peptide mimics. Binding and molecular docking studies revealed that F8 interacts similarly with W614A-3S and a Mim_F8-1 mimotope, despite their lack of sequence homology, suggesting structural mimicry. Finally, vaccination of mice with the purified Mim_F8-1 phage elicited HIV-1-neutralizing antibodies that bound to the cognate W614A-3S motif. Collectively, our findings provide new insights into the molecular design of immunogens to elicit antibodies with neutralizing properties.


Assuntos
Anticorpos Neutralizantes/imunologia , Mapeamento de Epitopos/métodos , Epitopos/imunologia , Anticorpos Anti-HIV/imunologia , Proteína gp41 do Envelope de HIV/imunologia , Animais , Anticorpos Monoclonais/imunologia , Bacteriófagos/imunologia , HIV-1 , Camundongos , Camundongos Endogâmicos BALB C , Modelos Moleculares , Simulação de Acoplamento Molecular , Testes de Neutralização , Peptídeos/administração & dosagem , Peptídeos/imunologia , Ligação Proteica/efeitos dos fármacos
20.
Virus Res ; 266: 58-68, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31004621

RESUMO

Respiratory syncytial virus (RSV) is a leading cause of infant hospitalization worldwide each year and there is presently no licensed vaccine to prevent severe RSV infections. Two major RSV glycoproteins, attachment (G) and fusion (F) protein, regulate viral replication and both proteins contain potential glycosylation sites which are highly variable for the G protein and conserved for the F protein among virus isolates. The RSV F sequence possesses five N-glycosylation sites located in the F2 subunit (N27 and N70), the p27 peptide (N116 and N126) and the F1 subunit (N500). The importance of RSV F N-glycosylation in virus replication and immunogenicity is not yet fully understood, and a better understanding may provide new insights for vaccine development. By using a BAC-based reverse genetics system, recombinant viruses expressing F proteins with loss of N-glycosylation sites were made. Mutant viruses with single N-glycosylation sites removed could be recovered, while this was not possible with the mutant with all N-glycosylation sites removed. Although the individual RSV F N-glycosylation sites were shown not to be essential for viral replication, they do contribute to the efficiency of in vitro and in vivo viral infection. To evaluate the role of N-glycosylation sites on RSV F antigenicity, serum antibody titers were determined after infection of BALB/c mice with RSV expressing the glycomutant F proteins. Infection with recombinant virus lacking the N-glycosylation site at position N116 (RSV F N116Q) resulted in significant higher neutralizing antibody titers compared to RSV F WT infection, which is surprising since this N-glycan is present in the p27 peptide which is assumed to be absent from the mature F protein in virions. Thus, single or combined RSV F glycomutations which affect virus replication and fusogenicity, and which may induce enhanced antibody responses upon immunization could have the potential to improve the efficacy of RSV LAV approaches.


Assuntos
Infecções por Vírus Respiratório Sincicial/virologia , Vírus Sincicial Respiratório Humano/fisiologia , Vírus Sincicial Respiratório Humano/patogenicidade , Proteínas Virais de Fusão/metabolismo , Animais , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Linhagem Celular Tumoral , Cercopithecus aethiops , Feminino , Células Gigantes/virologia , Glicosilação , Humanos , Imunização , Imunogenicidade da Vacina , Camundongos Endogâmicos BALB C , Mutação , Infecções por Vírus Respiratório Sincicial/metabolismo , Infecções por Vírus Respiratório Sincicial/patologia , Vírus Sincicial Respiratório Humano/crescimento & desenvolvimento , Vírus Sincicial Respiratório Humano/imunologia , Células Vero , Proteínas Virais de Fusão/genética , Proteínas Virais de Fusão/imunologia , Replicação Viral
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA