RESUMO
BACKGROUND & AIMS: Chronic hepatitis B is a global public health problem, and coinfection with hepatitis delta virus (HDV) worsens disease outcome. Here, we describe a hepatitis B virus (HBV) surface antigen (HBsAg)-targeting monoclonal antibody (mAb) with the potential to treat chronic hepatitis B and chronic hepatitis D. METHODS: HBsAg-specific mAbs were isolated from memory B cells of HBV vaccinated individuals. In vitro neutralization was determined against HBV and HDV enveloped with HBsAg representing eight HBV genotypes. Human liver-chimeric mice were treated twice weekly with a candidate mAb starting 3 weeks post HBV inoculation (spreading phase) or during stable HBV or HBV/HDV coinfection (chronic phase). RESULTS: From a panel of human anti-HBs mAbs, VIR-3434 was selected and engineered for pre-clinical development. VIR-3434 targets a conserved, conformational epitope within the antigenic loop of HBsAg and neutralized HBV and HDV infection with higher potency than hepatitis B immunoglobulins in vitro. Neutralization was pan-genotypic against strains representative of HBV genotypes A-H. In the spreading phase of HBV infection in human liver-chimeric mice, a parental mAb of VIR-3434 (HBC34) prevented HBV dissemination and the increase in intrahepatic HBV RNA and covalently closed circular DNA. In the chronic phase of HBV infection or co-infection with HDV, HBC34 treatment decreased circulating HBsAg by >1 log and HDV RNA by >2 logs. CONCLUSIONS: The potently neutralizing anti-HBs mAb VIR-3434 reduces circulating HBsAg and HBV/HDV viremia in human liver-chimeric mice. VIR-3434 is currently in clinical development for treatment of patients with chronic hepatitis B or D. IMPACT AND IMPLICATIONS: Chronic infection with hepatitis B virus and co-infection with hepatitis D virus place approximately 290 million individuals worldwide at risk of severe liver disease and cancer. Available treatments result in low rates of functional cure or require lifelong therapy that does not eliminate the risk of liver disease. We isolated and characterized a potent human antibody that neutralizes hepatitis B and D viruses and reduces infection in a mouse model. This antibody could provide a new treatment for patients with chronic hepatitis B and D.
RESUMO
The coronavirus spike glycoprotein attaches to host receptors and mediates viral fusion. Using a broad screening approach, we isolated seven monoclonal antibodies (mAbs) that bind to all human-infecting coronavirus spike proteins from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immune donors. These mAbs recognize the fusion peptide and acquire affinity and breadth through somatic mutations. Despite targeting a conserved motif, only some mAbs show broad neutralizing activity in vitro against alpha- and betacoronaviruses, including animal coronaviruses WIV-1 and PDF-2180. Two selected mAbs also neutralize Omicron BA.1 and BA.2 authentic viruses and reduce viral burden and pathology in vivo. Structural and functional analyses showed that the fusion peptide-specific mAbs bound with different modalities to a cryptic epitope hidden in prefusion stabilized spike, which became exposed upon binding of angiotensin-converting enzyme 2 (ACE2) or ACE2-mimicking mAbs.
Assuntos
Enzima de Conversão de Angiotensina 2 , Anticorpos Monoclonais , Anticorpos Antivirais , Anticorpos Amplamente Neutralizantes , COVID-19 , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus , Enzima de Conversão de Angiotensina 2/química , Animais , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/isolamento & purificação , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/isolamento & purificação , Anticorpos Amplamente Neutralizantes/imunologia , COVID-19/imunologia , Humanos , Peptídeos/imunologia , Ligação Proteica , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/imunologiaRESUMO
SARS-CoV-2 infection-which involves both cell attachment and membrane fusion-relies on the angiotensin-converting enzyme 2 (ACE2) receptor, which is paradoxically found at low levels in the respiratory tract1-3, suggesting that there may be additional mechanisms facilitating infection. Here we show that C-type lectin receptors, DC-SIGN, L-SIGN and the sialic acid-binding immunoglobulin-like lectin 1 (SIGLEC1) function as attachment receptors by enhancing ACE2-mediated infection and modulating the neutralizing activity of different classes of spike-specific antibodies. Antibodies to the amino-terminal domain or to the conserved site at the base of the receptor-binding domain, while poorly neutralizing infection of ACE2-overexpressing cells, effectively block lectin-facilitated infection. Conversely, antibodies to the receptor binding motif, while potently neutralizing infection of ACE2-overexpressing cells, poorly neutralize infection of cells expressing DC-SIGN or L-SIGN and trigger fusogenic rearrangement of the spike, promoting cell-to-cell fusion. Collectively, these findings identify a lectin-dependent pathway that enhances ACE2-dependent infection by SARS-CoV-2 and reveal distinct mechanisms of neutralization by different classes of spike-specific antibodies.
Assuntos
Anticorpos Neutralizantes/imunologia , Lectinas/metabolismo , SARS-CoV-2/metabolismo , SARS-CoV-2/patogenicidade , Enzima de Conversão de Angiotensina 2/metabolismo , Animais , Moléculas de Adesão Celular/metabolismo , Fusão Celular , Linhagem Celular , Cricetinae , Feminino , Humanos , Lectinas/imunologia , Lectinas Tipo C/metabolismo , Fusão de Membrana , Receptores de Superfície Celular/metabolismo , SARS-CoV-2/imunologia , Lectina 1 Semelhante a Ig de Ligação ao Ácido Siálico/metabolismo , Glicoproteína da Espícula de Coronavírus/imunologia , Glicoproteína da Espícula de Coronavírus/metabolismoRESUMO
The spillovers of betacoronaviruses in humans and the emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants highlight the need for broad coronavirus countermeasures. We describe five monoclonal antibodies (mAbs) cross-reacting with the stem helix of multiple betacoronavirus spike glycoproteins isolated from COVID-19 convalescent individuals. Using structural and functional studies, we show that the mAb with the greatest breadth (S2P6) neutralizes pseudotyped viruses from three different subgenera through the inhibition of membrane fusion, and we delineate the molecular basis for its cross-reactivity. S2P6 reduces viral burden in hamsters challenged with SARS-CoV-2 through viral neutralization and Fc-mediated effector functions. Stem helix antibodies are rare, oftentimes of narrow specificity, and can acquire neutralization breadth through somatic mutations. These data provide a framework for structure-guided design of pan-betacoronavirus vaccines eliciting broad protection.
Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Betacoronavirus/imunologia , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/imunologia , Vacinas Virais/imunologia , Internalização do Vírus , Animais , Anticorpos Monoclonais/isolamento & purificação , Anticorpos Neutralizantes/isolamento & purificação , Convalescença , Cricetinae , Reações Cruzadas , Humanos , Fragmentos Fab das Imunoglobulinas/imunologia , Fragmentos Fc das Imunoglobulinas/imunologia , Células Jurkat , Pulmão/imunologia , Fusão de Membrana/imunologia , Testes de Neutralização , Mapeamento de Peptídeos , Conformação Proteica em alfa-Hélice , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/genética , Carga Viral/imunologiaRESUMO
A novel variant of concern (VOC) named CAL.20C (B.1.427/B.1.429), which was originally detected in California, carries spike glycoprotein mutations S13I in the signal peptide, W152C in the N-terminal domain (NTD), and L452R in the receptor-binding domain (RBD). Plasma from individuals vaccinated with a Wuhan-1 isolate-based messenger RNA vaccine or from convalescent individuals exhibited neutralizing titers that were reduced 2- to 3.5-fold against the B.1.427/B.1.429 variant relative to wild-type pseudoviruses. The L452R mutation reduced neutralizing activity in 14 of 34 RBD-specific monoclonal antibodies (mAbs). The S13I and W152C mutations resulted in total loss of neutralization for 10 of 10 NTD-specific mAbs because the NTD antigenic supersite was remodeled by a shift of the signal peptide cleavage site and the formation of a new disulfide bond, as revealed by mass spectrometry and structural studies.
Assuntos
COVID-19/virologia , Evasão da Resposta Imune , SARS-CoV-2/imunologia , SARS-CoV-2/patogenicidade , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/imunologia , Vacina de mRNA-1273 contra 2019-nCoV , Substituição de Aminoácidos , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/sangue , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/sangue , Anticorpos Antivirais/imunologia , Antígenos Virais/imunologia , Vacina BNT162 , COVID-19/imunologia , Vacinas contra COVID-19/imunologia , Microscopia Crioeletrônica , Humanos , Modelos Moleculares , Mutação , Testes de Neutralização , Conformação Proteica , Domínios Proteicos , Domínios e Motivos de Interação entre Proteínas , Subunidades Proteicas/química , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/químicaRESUMO
SARS-CoV-2 entry is mediated by the spike (S) glycoprotein which contains the receptor-binding domain (RBD) and the N-terminal domain (NTD) as the two main targets of neutralizing antibodies (Abs). A novel variant of concern (VOC) named CAL.20C (B.1.427/B.1.429) was originally detected in California and is currently spreading throughout the US and 29 additional countries. It is unclear whether antibody responses to SARS-CoV-2 infection or to the prototypic Wuhan-1 isolate-based vaccines will be impacted by the three B.1.427/B.1.429 S mutations: S13I, W152C and L452R. Here, we assessed neutralizing Ab responses following natural infection or mRNA vaccination using pseudoviruses expressing the wildtype or the B.1.427/B.1.429 S protein. Plasma from vaccinated or convalescent individuals exhibited neutralizing titers, which were reduced 3-6 fold against the B.1.427/B.1.429 variant relative to wildtype pseudoviruses. The RBD L452R mutation reduced or abolished neutralizing activity of 14 out of 35 RBD-specific monoclonal antibodies (mAbs), including three clinical-stage mAbs. Furthermore, we observed a complete loss of B.1.427/B.1.429 neutralization for a panel of mAbs targeting the N-terminal domain due to a large structural rearrangement of the NTD antigenic supersite involving an S13I-mediated shift of the signal peptide cleavage site. These data warrant closer monitoring of signal peptide variants and their involvement in immune evasion and show that Abs directed to the NTD impose a selection pressure driving SARS-CoV-2 viral evolution through conventional and unconventional escape mechanisms.
RESUMO
Transmission of SARS-CoV-2 is uncontrolled in many parts of the world; control is compounded in some areas by the higher transmission potential of the B.1.1.7 variant1, which has now been reported in 94 countries. It is unclear whether the response of the virus to vaccines against SARS-CoV-2 on the basis of the prototypic strain will be affected by the mutations found in B.1.1.7. Here we assess the immune responses of individuals after vaccination with the mRNA-based vaccine BNT162b22. We measured neutralizing antibody responses after the first and second immunizations using pseudoviruses that expressed the wild-type spike protein or a mutated spike protein that contained the eight amino acid changes found in the B.1.1.7 variant. The sera from individuals who received the vaccine exhibited a broad range of neutralizing titres against the wild-type pseudoviruses that were modestly reduced against the B.1.1.7 variant. This reduction was also evident in sera from some patients who had recovered from COVID-19. Decreased neutralization of the B.1.1.7 variant was also observed for monoclonal antibodies that target the N-terminal domain (9 out of 10) and the receptor-binding motif (5 out of 31), but not for monoclonal antibodies that recognize the receptor-binding domain that bind outside the receptor-binding motif. Introduction of the mutation that encodes the E484K substitution in the B.1.1.7 background to reflect a newly emerged variant of concern (VOC 202102/02) led to a more-substantial loss of neutralizing activity by vaccine-elicited antibodies and monoclonal antibodies (19 out of 31) compared with the loss of neutralizing activity conferred by the mutations in B.1.1.7 alone. The emergence of the E484K substitution in a B.1.1.7 background represents a threat to the efficacy of the BNT162b2 vaccine.
Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Vacinas contra COVID-19/imunologia , COVID-19/imunologia , COVID-19/terapia , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Vacinas Sintéticas/imunologia , Idoso , Idoso de 80 Anos ou mais , Enzima de Conversão de Angiotensina 2/metabolismo , Anticorpos Monoclonais/imunologia , Anticorpos Monoclonais/isolamento & purificação , Anticorpos Neutralizantes/isolamento & purificação , Anticorpos Antivirais/isolamento & purificação , COVID-19/metabolismo , COVID-19/virologia , Feminino , Células HEK293 , Humanos , Evasão da Resposta Imune/genética , Evasão da Resposta Imune/imunologia , Imunização Passiva , Masculino , Pessoa de Meia-Idade , Modelos Moleculares , Mutação , Testes de Neutralização , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética , Glicoproteína da Espícula de Coronavírus/metabolismo , Vacinas Sintéticas/administração & dosagem , Soroterapia para COVID-19 , Vacinas de mRNARESUMO
The SARS-CoV-2 spike (S) glycoprotein contains an immunodominant receptor-binding domain (RBD) targeted by most neutralizing antibodies (Abs) in COVID-19 patient plasma. Little is known about neutralizing Abs binding to epitopes outside the RBD and their contribution to protection. Here, we describe 41 human monoclonal Abs (mAbs) derived from memory B cells, which recognize the SARS-CoV-2 S N-terminal domain (NTD) and show that a subset of them neutralize SARS-CoV-2 ultrapotently. We define an antigenic map of the SARS-CoV-2 NTD and identify a supersite (designated site i) recognized by all known NTD-specific neutralizing mAbs. These mAbs inhibit cell-to-cell fusion, activate effector functions, and protect Syrian hamsters from SARS-CoV-2 challenge, albeit selecting escape mutants in some animals. Indeed, several SARS-CoV-2 variants, including the B.1.1.7, B.1.351, and P.1 lineages, harbor frequent mutations within the NTD supersite, suggesting ongoing selective pressure and the importance of NTD-specific neutralizing mAbs for protective immunity and vaccine design.
Assuntos
Antígenos Virais/imunologia , SARS-CoV-2/imunologia , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , COVID-19/imunologia , COVID-19/virologia , Cricetinae , Mapeamento de Epitopos , Variação Genética , Modelos Moleculares , Mutação/genética , Testes de Neutralização , Domínios Proteicos , RNA Viral/genética , SARS-CoV-2/isolamento & purificação , SARS-CoV-2/ultraestruturaRESUMO
Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2) transmission is uncontrolled in many parts of the world, compounded in some areas by higher transmission potential of the B1.1.7 variant now seen in 50 countries. It is unclear whether responses to SARS-CoV-2 vaccines based on the prototypic strain will be impacted by mutations found in B.1.1.7. Here we assessed immune responses following vaccination with mRNA-based vaccine BNT162b2. We measured neutralising antibody responses following a single immunization using pseudoviruses expressing the wild-type Spike protein or the 8 amino acid mutations found in the B.1.1.7 spike protein. The vaccine sera exhibited a broad range of neutralising titres against the wild-type pseudoviruses that were modestly reduced against B.1.1.7 variant. This reduction was also evident in sera from some convalescent patients. Decreased B.1.1.7 neutralisation was also observed with monoclonal antibodies targeting the N-terminal domain (9 out of 10), the Receptor Binding Motif (RBM) (5 out of 31), but not in neutralising mAbs binding outside the RBM. Introduction of the E484K mutation in a B.1.1.7 background to reflect newly emerging viruses in the UK led to a more substantial loss of neutralising activity by vaccine-elicited antibodies and mAbs (19 out of 31) over that conferred by the B.1.1.7 mutations alone. E484K emergence on a B.1.1.7 background represents a threat to the vaccine BNT162b.
RESUMO
SARS-CoV-2 entry into host cells is orchestrated by the spike (S) glycoprotein that contains an immunodominant receptor-binding domain (RBD) targeted by the largest fraction of neutralizing antibodies (Abs) in COVID-19 patient plasma. Little is known about neutralizing Abs binding to epitopes outside the RBD and their contribution to protection. Here, we describe 41 human monoclonal Abs (mAbs) derived from memory B cells, which recognize the SARS-CoV-2 S N-terminal domain (NTD) and show that a subset of them neutralize SARS-CoV-2 ultrapotently. We define an antigenic map of the SARS-CoV-2 NTD and identify a supersite recognized by all known NTD-specific neutralizing mAbs. These mAbs inhibit cell-to-cell fusion, activate effector functions, and protect Syrian hamsters from SARS-CoV-2 challenge. SARS-CoV-2 variants, including the 501Y.V2 and B.1.1.7 lineages, harbor frequent mutations localized in the NTD supersite suggesting ongoing selective pressure and the importance of NTD-specific neutralizing mAbs to protective immunity.
RESUMO
Efficient therapeutic options are needed to control the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that has caused more than 922,000 fatalities as of 13 September 2020. We report the isolation and characterization of two ultrapotent SARS-CoV-2 human neutralizing antibodies (S2E12 and S2M11) that protect hamsters against SARS-CoV-2 challenge. Cryo-electron microscopy structures show that S2E12 and S2M11 competitively block angiotensin-converting enzyme 2 (ACE2) attachment and that S2M11 also locks the spike in a closed conformation by recognition of a quaternary epitope spanning two adjacent receptor-binding domains. Antibody cocktails that include S2M11, S2E12, or the previously identified S309 antibody broadly neutralize a panel of circulating SARS-CoV-2 isolates and activate effector functions. Our results pave the way to implement antibody cocktails for prophylaxis or therapy, circumventing or limiting the emergence of viral escape mutants.
Assuntos
Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Betacoronavirus/imunologia , Infecções por Coronavirus/prevenção & controle , Pandemias/prevenção & controle , Peptidil Dipeptidase A/imunologia , Pneumonia Viral/prevenção & controle , Glicoproteína da Espícula de Coronavírus/antagonistas & inibidores , Motivos de Aminoácidos/imunologia , Enzima de Conversão de Angiotensina 2 , Animais , Anticorpos Neutralizantes/administração & dosagem , Anticorpos Neutralizantes/isolamento & purificação , Anticorpos Antivirais/administração & dosagem , Anticorpos Antivirais/isolamento & purificação , Células CHO , COVID-19 , Infecções por Coronavirus/terapia , Cricetinae , Cricetulus , Microscopia Crioeletrônica , Células HEK293 , Humanos , Epitopos Imunodominantes/química , Epitopos Imunodominantes/imunologia , Microscopia Eletrônica , Pneumonia Viral/terapia , Domínios Proteicos/imunologia , SARS-CoV-2 , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/imunologiaRESUMO
SARS-CoV-2 is a newly emerged coronavirus responsible for the current COVID-19 pandemic that has resulted in more than one million infections and 73,000 deaths 1,2 . Vaccine and therapeutic discovery efforts are paramount to curb the pandemic spread of this zoonotic virus. The SARS-CoV-2 spike (S) glycoprotein promotes entry into host cells and is the main target of neutralizing antibodies. Here we describe multiple monoclonal antibodies targeting SARS-CoV-2 S identified from memory B cells of a SARS survivor infected in 2003. One antibody, named S309, potently neutralizes SARS-CoV-2 and SARS-CoV pseudoviruses as well as authentic SARS-CoV-2 by engaging the S receptor-binding domain. Using cryo-electron microscopy and binding assays, we show that S309 recognizes a glycan-containing epitope that is conserved within the sarbecovirus subgenus, without competing with receptor attachment. Antibody cocktails including S309 along with other antibodies identified here further enhanced SARS-CoV-2 neutralization and may limit the emergence of neutralization-escape mutants. These results pave the way for using S309 and S309-containing antibody cocktails for prophylaxis in individuals at high risk of exposure or as a post-exposure therapy to limit or treat severe disease.
RESUMO
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a newly emerged coronavirus that is responsible for the current pandemic of coronavirus disease 2019 (COVID-19), which has resulted in more than 3.7 million infections and 260,000 deaths as of 6 May 20201,2. Vaccine and therapeutic discovery efforts are paramount to curb the pandemic spread of this zoonotic virus. The SARS-CoV-2 spike (S) glycoprotein promotes entry into host cells and is the main target of neutralizing antibodies. Here we describe several monoclonal antibodies that target the S glycoprotein of SARS-CoV-2, which we identified from memory B cells of an individual who was infected with severe acute respiratory syndrome coronavirus (SARS-CoV) in 2003. One antibody (named S309) potently neutralizes SARS-CoV-2 and SARS-CoV pseudoviruses as well as authentic SARS-CoV-2, by engaging the receptor-binding domain of the S glycoprotein. Using cryo-electron microscopy and binding assays, we show that S309 recognizes an epitope containing a glycan that is conserved within the Sarbecovirus subgenus, without competing with receptor attachment. Antibody cocktails that include S309 in combination with other antibodies that we identified further enhanced SARS-CoV-2 neutralization, and may limit the emergence of neutralization-escape mutants. These results pave the way for using S309 and antibody cocktails containing S309 for prophylaxis in individuals at a high risk of exposure or as a post-exposure therapy to limit or treat severe disease.
Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Betacoronavirus/imunologia , Reações Cruzadas/imunologia , Síndrome Respiratória Aguda Grave/imunologia , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Enzima de Conversão de Angiotensina 2 , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/farmacologia , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/farmacologia , Anticorpos Antivirais/química , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/farmacologia , Citotoxicidade Celular Dependente de Anticorpos/efeitos dos fármacos , Citotoxicidade Celular Dependente de Anticorpos/imunologia , Linfócitos B/imunologia , Betacoronavirus/química , Betacoronavirus/efeitos dos fármacos , COVID-19 , Chlorocebus aethiops , Infecções por Coronavirus/imunologia , Infecções por Coronavirus/prevenção & controle , Infecções por Coronavirus/terapia , Infecções por Coronavirus/virologia , Reações Cruzadas/efeitos dos fármacos , Microscopia Crioeletrônica , Epitopos de Linfócito B/química , Epitopos de Linfócito B/imunologia , Células HEK293 , Humanos , Evasão da Resposta Imune/imunologia , Fragmentos Fab das Imunoglobulinas/química , Fragmentos Fab das Imunoglobulinas/imunologia , Fragmentos Fab das Imunoglobulinas/farmacologia , Memória Imunológica/imunologia , Células Matadoras Naturais/efeitos dos fármacos , Células Matadoras Naturais/imunologia , Modelos Moleculares , Testes de Neutralização , Pandemias/prevenção & controle , Peptidil Dipeptidase A/química , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/imunologia , Pneumonia Viral/prevenção & controle , Pneumonia Viral/terapia , Pneumonia Viral/virologia , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/química , Coronavírus Relacionado à Síndrome Respiratória Aguda Grave/efeitos dos fármacos , SARS-CoV-2 , Síndrome Respiratória Aguda Grave/virologia , Glicoproteína da Espícula de Coronavírus/química , Células VeroRESUMO
The respiratory syncytial virus (RSV) fusion (F) glycoprotein is a major target of neutralizing antibodies arising from natural infection, and antibodies that specifically bind to the prefusion conformation of RSV F generally demonstrate the greatest neutralization potency. Prefusion-stabilized RSV F variants have been engineered as vaccine antigens, but crystal structures of these variants have revealed conformational differences in a key antigenic site located at the apex of the trimer, referred to as antigenic site Ø. Currently, it is unclear if flexibility in this region is an inherent property of prefusion RSV F or if it is related to inadequate stabilization of site Ø in the engineered variants. Therefore, we set out to investigate the conformational flexibility of antigenic site Ø, as well as the ability of the human immune system to recognize alternative conformations of this site, by determining crystal structures of prefusion RSV F bound to neutralizing human-derived antibodies AM22 and RSD5. Both antibodies bound with high affinity and were specific for the prefusion conformation of RSV F. Crystal structures of the complexes revealed that the antibodies recognized distinct conformations of antigenic site Ø, each diverging at a conserved proline residue located in the middle of an α-helix. These data suggest that antigenic site Ø exists as an ensemble of conformations, with individual antibodies recognizing discrete states. Collectively, these results have implications for the refolding of pneumovirus and paramyxovirus fusion proteins and should inform development of prefusion-stabilized RSV F vaccine candidates.
Assuntos
Antígenos Virais/química , Vírus Sincicial Respiratório Humano/imunologia , Proteínas Virais de Fusão/química , Proteínas Virais de Fusão/imunologia , Sequência de Aminoácidos , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Complexo Antígeno-Anticorpo/química , Complexo Antígeno-Anticorpo/imunologia , Antígenos Virais/genética , Antígenos Virais/imunologia , Sítios de Ligação/genética , Cristalografia por Raios X , Humanos , Modelos Moleculares , Prolina/química , Conformação Proteica , Vírus Sincicial Respiratório Humano/química , Vírus Sincicial Respiratório Humano/genética , Proteínas Virais de Fusão/genéticaRESUMO
Emerging multidrug-resistant bacteria are a challenge for modern medicine, but how these pathogens are so successful is not fully understood. Robust antibacterial vaccines have prevented and reduced resistance suggesting a pivotal role for immunity in deterring antibiotic resistance. Here, we show the increased prevalence of Klebsiella pneumoniae lipopolysaccharide O2 serotype strains in all major drug resistance groups correlating with a paucity of anti-O2 antibodies in human B cell repertoires. We identify human monoclonal antibodies to O-antigens that are highly protective in mouse models of infection, even against heavily encapsulated strains. These antibodies, including a rare anti-O2 specific antibody, synergistically protect against drug-resistant strains in adjunctive therapy with meropenem, a standard-of-care antibiotic, confirming the importance of immune assistance in antibiotic therapy. These findings support an antibody-based immunotherapeutic strategy even for highly resistant K. pneumoniae infections, and underscore the effect humoral immunity has on evolving drug resistance.
Assuntos
Anticorpos Antibacterianos/uso terapêutico , Anticorpos Monoclonais/uso terapêutico , Infecções por Klebsiella/terapia , Klebsiella pneumoniae/fisiologia , Antígenos O/imunologia , Animais , Antibacterianos/uso terapêutico , Anticorpos Antibacterianos/imunologia , Anticorpos Monoclonais/imunologia , Linhagem Celular , Modelos Animais de Doenças , Farmacorresistência Bacteriana Múltipla/genética , Farmacorresistência Bacteriana Múltipla/imunologia , Humanos , Imunidade Humoral , Fatores Imunológicos/uso terapêutico , Imunoterapia/métodos , Infecções por Klebsiella/imunologia , Infecções por Klebsiella/microbiologia , Infecções por Klebsiella/mortalidade , Klebsiella pneumoniae/efeitos dos fármacos , Meropeném , Camundongos , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Sorogrupo , Taxa de Sobrevida , Tienamicinas/uso terapêuticoRESUMO
Zika virus (ZIKV), a mosquito-borne flavivirus, causes devastating congenital birth defects. We isolated a human monoclonal antibody (mAb), ZKA190, that potently cross-neutralizes multi-lineage ZIKV strains. ZKA190 is highly effective in vivo in preventing morbidity and mortality of ZIKV-infected mice. NMR and cryo-electron microscopy show its binding to an exposed epitope on DIII of the E protein. ZKA190 Fab binds all 180 E protein copies, altering the virus quaternary arrangement and surface curvature. However, ZIKV escape mutants emerged in vitro and in vivo in the presence of ZKA190, as well as of other neutralizing mAbs. To counter this problem, we developed a bispecific antibody (FIT-1) comprising ZKA190 and a second mAb specific for DII of E protein. In addition to retaining high in vitro and in vivo potencies, FIT-1 robustly prevented viral escape, warranting its development as a ZIKV immunotherapy.
Assuntos
Anticorpos Monoclonais/uso terapêutico , Anticorpos Neutralizantes/uso terapêutico , Anticorpos Antivirais/uso terapêutico , Infecção por Zika virus/terapia , Zika virus/química , Sequência de Aminoácidos , Animais , Anticorpos Monoclonais/administração & dosagem , Anticorpos Monoclonais/química , Anticorpos Neutralizantes/administração & dosagem , Anticorpos Neutralizantes/química , Anticorpos Antivirais/administração & dosagem , Anticorpos Antivirais/química , Microscopia Crioeletrônica , Epitopos , Humanos , Espectroscopia de Ressonância Magnética , Camundongos , Modelos Moleculares , Alinhamento de Sequência , Proteínas do Envelope Viral/química , Zika virus/imunologiaRESUMO
Human cytomegalovirus encodes at least 25 membrane glycoproteins that are found in the viral envelope(1). While gB represents the fusion protein, two glycoprotein complexes control the tropism of the virus: the gHgLgO trimer is involved in the infection of fibroblasts, and the gHgLpUL128L pentamer is required for infection of endothelial, epithelial and myeloid cells(2-5). Two reports suggested that gB binds to ErbB1 and PDGFRα (refs 6,7); however, these results do not explain the tropism of the virus and were recently challenged(8,9). Here, we provide a 19â Å reconstruction for the gHgLgO trimer and show that it binds with high affinity through the gO subunit to PDGFRα, which is expressed on fibroblasts but not on epithelial cells. We also provide evidence that the trimer is essential for viral entry in both fibroblasts and epithelial cells. Furthermore, we identify the pentamer, which is essential for infection of epithelial cells, as a trigger for the ErbB pathway. These findings help explain the broad tropism of human cytomegalovirus and indicate that PDGFRα and the viral gO subunit could be targeted by novel anti-viral therapies.
Assuntos
Glicoproteínas de Membrana/metabolismo , Receptor alfa de Fator de Crescimento Derivado de Plaquetas/metabolismo , Receptores Virais/metabolismo , Proteínas do Envelope Viral/metabolismo , Linhagem Celular , Humanos , Glicoproteínas de Membrana/química , Microscopia Eletrônica , Ligação Proteica , Conformação Proteica , Proteínas do Envelope Viral/químicaRESUMO
Zika virus (ZIKV), a mosquito-borne flavivirus with homology to Dengue virus (DENV), has become a public health emergency. By characterizing memory lymphocytes from ZIKV-infected patients, we dissected ZIKV-specific and DENV-cross-reactive immune responses. Antibodies to nonstructural protein 1 (NS1) were largely ZIKV-specific and were used to develop a serological diagnostic tool. In contrast, antibodies against E protein domain I/II (EDI/II) were cross-reactive and, although poorly neutralizing, potently enhanced ZIKV and DENV infection in vitro and lethally enhanced DENV disease in mice. Memory T cells against NS1 or E proteins were poorly cross-reactive, even in donors preexposed to DENV. The most potent neutralizing antibodies were ZIKV-specific and targeted EDIII or quaternary epitopes on infectious virus. An EDIII-specific antibody protected mice from lethal ZIKV infection, illustrating the potential for antibody-based therapy.
Assuntos
Anticorpos Monoclonais/imunologia , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Infecção por Zika virus/imunologia , Zika virus/imunologia , Animais , Anticorpos Monoclonais/química , Anticorpos Monoclonais/uso terapêutico , Anticorpos Neutralizantes/química , Anticorpos Neutralizantes/uso terapêutico , Anticorpos Antivirais/química , Anticorpos Antivirais/uso terapêutico , Especificidade de Anticorpos , Reações Cruzadas , Vírus da Dengue/imunologia , Modelos Animais de Doenças , Humanos , Epitopos Imunodominantes/imunologia , Memória Imunológica , Estrutura Terciária de Proteína , Linfócitos T/imunologia , Proteínas do Envelope Viral/imunologia , Proteínas não Estruturais Virais/imunologia , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/terapiaRESUMO
Influenza virus remains a threat because of its ability to evade vaccine-induced immune responses due to antigenic drift. Here, we describe the isolation, evolution, and structure of a broad-spectrum human monoclonal antibody (mAb), MEDI8852, effectively reacting with all influenza A hemagglutinin (HA) subtypes. MEDI8852 uses the heavy-chain VH6-1 gene and has higher potency and breadth when compared to other anti-stem antibodies. MEDI8852 is effective in mice and ferrets with a therapeutic window superior to that of oseltamivir. Crystallographic analysis of Fab alone or in complex with H5 or H7 HA proteins reveals that MEDI8852 binds through a coordinated movement of CDRs to a highly conserved epitope encompassing a hydrophobic groove in the fusion domain and a large portion of the fusion peptide, distinguishing it from other structurally characterized cross-reactive antibodies. The unprecedented breadth and potency of neutralization by MEDI8852 support its development as immunotherapy for influenza virus-infected humans.