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1.
Cell Host Microbe ; 32(5): 693-709.e7, 2024 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-38670093

RESUMO

A major goal of HIV-1 vaccine development is the induction of broadly neutralizing antibodies (bnAbs). Although success has been achieved in initiating bnAb B cell lineages, design of boosting immunogens that select for bnAb B cell receptors with improbable mutations required for bnAb affinity maturation remains difficult. Here, we demonstrate a process for designing boosting immunogens for a V3-glycan bnAb B cell lineage. The immunogens induced affinity-matured antibodies by selecting for functional improbable mutations in bnAb precursor knockin mice. Moreover, we show similar success in prime and boosting with nucleoside-modified mRNA-encoded HIV-1 envelope trimer immunogens, with improved selection by mRNA immunogens of improbable mutations required for bnAb binding to key envelope glycans. These results demonstrate the ability of both protein and mRNA prime-boost immunogens for selection of rare B cell lineage intermediates with neutralizing breadth after bnAb precursor expansion, a key proof of concept and milestone toward development of an HIV-1 vaccine.


Assuntos
Vacinas contra a AIDS , Anticorpos Neutralizantes , Linfócitos B , Anticorpos Anti-HIV , HIV-1 , Vacinas contra a AIDS/imunologia , Vacinas contra a AIDS/genética , Animais , Anticorpos Anti-HIV/imunologia , HIV-1/imunologia , HIV-1/genética , Camundongos , Anticorpos Neutralizantes/imunologia , Linfócitos B/imunologia , Humanos , Infecções por HIV/imunologia , Infecções por HIV/prevenção & controle , Anticorpos Amplamente Neutralizantes/imunologia , Mutação , Desenvolvimento de Vacinas , Imunização Secundária , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/genética
2.
Sci Adv ; 10(5): eadj0396, 2024 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-38306419

RESUMO

The HIV-1 Envelope (Env) glycoprotein facilitates host cell fusion through a complex series of receptor-induced structural changes. Although remarkable progress has been made in understanding the structures of various Env conformations, microsecond timescale dynamics have not been studied experimentally. Here, we used time-resolved, temperature-jump small-angle x-ray scattering to monitor structural rearrangements in an HIV-1 Env SOSIP ectodomain construct with microsecond precision. In two distinct Env variants, we detected a transition that correlated with known Env structure rearrangements with a time constant in the hundreds of microseconds range. A previously unknown structural transition was also observed, which occurred with a time constant below 10 µs, and involved an order-to-disorder transition in the trimer apex. Using this information, we engineered an Env SOSIP construct that locks the trimer in the prefusion closed state by connecting adjacent protomers via disulfides. Our findings show that the microsecond timescale structural dynamics play an essential role in controlling the Env conformation with impacts on vaccine design.


Assuntos
HIV-1 , Produtos do Gene env do Vírus da Imunodeficiência Humana , Produtos do Gene env do Vírus da Imunodeficiência Humana/química , Anticorpos Anti-HIV , Conformação Molecular , Multimerização Proteica , Conformação Proteica
3.
bioRxiv ; 2024 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-38405707

RESUMO

A recombinant lineage of the SARS-CoV-2 Omicron variant, named XBB, appeared in late 2022 and evolved descendants that successively swept local and global populations. XBB lineage members were noted for their improved immune evasion and transmissibility. Here, we determine cryo-EM structures of XBB.1.5, XBB.1.16, EG.5 and EG.5.1 spike (S) ectodomains to reveal reinforced 3-RBD-down receptor inaccessible closed states mediated by interprotomer receptor binding domain (RBD) interactions previously observed in BA.1 and BA.2. Improved XBB.1.5 and XBB.1.16 RBD stability compensated for stability loss caused by early Omicron mutations, while the F456L substitution reduced EG.5 RBD stability. S1 subunit mutations had long-range impacts on conformation and epitope presentation in the S2 subunit. Our results reveal continued S protein evolution via simultaneous optimization of multiple parameters including stability, receptor binding and immune evasion, and the dramatic effects of relatively few residue substitutions in altering the S protein conformational landscape.

4.
Cell ; 187(1): 79-94.e24, 2024 01 04.
Artigo em Inglês | MEDLINE | ID: mdl-38181743

RESUMO

The CD4-binding site (CD4bs) is a conserved epitope on HIV-1 envelope (Env) that can be targeted by protective broadly neutralizing antibodies (bnAbs). HIV-1 vaccines have not elicited CD4bs bnAbs for many reasons, including the occlusion of CD4bs by glycans, expansion of appropriate naive B cells with immunogens, and selection of functional antibody mutations. Here, we demonstrate that immunization of macaques with a CD4bs-targeting immunogen elicits neutralizing bnAb precursors with structural and genetic features of CD4-mimicking bnAbs. Structures of the CD4bs nAb bound to HIV-1 Env demonstrated binding angles and heavy-chain interactions characteristic of all known human CD4-mimicking bnAbs. Macaque nAb were derived from variable and joining gene segments orthologous to the genes of human VH1-46-class bnAb. This vaccine study initiated in primates the B cells from which CD4bs bnAbs can derive, accomplishing the key first step in the development of an effective HIV-1 vaccine.


Assuntos
Vacinas contra a AIDS , HIV-1 , Animais , Humanos , Anticorpos Amplamente Neutralizantes , Antígenos CD4 , Moléculas de Adesão Celular , HIV-1/fisiologia , Macaca , Vacinas contra a AIDS/imunologia
5.
bioRxiv ; 2023 May 18.
Artigo em Inglês | MEDLINE | ID: mdl-37292605

RESUMO

The HIV-1 Envelope (Env) glycoprotein facilitates host cell fusion through a complex series of receptor-induced structural changes. Although significant progress has been made in understanding the structures of various Env conformations and transition intermediates that occur within the millisecond timescale, faster transitions in the microsecond timescale have not yet been observed. In this study, we employed time-resolved, temperature-jump small angle X-ray scattering to monitor structural rearrangements in an HIV-1 Env ectodomain construct with microsecond precision. We detected a transition correlated with Env opening that occurs in the hundreds of microseconds range and another more rapid transition that preceded this opening. Model fitting indicated that the early rapid transition involved an order-to-disorder transition in the trimer apex loop contacts, suggesting that conventional conformation-locking design strategies that target the allosteric machinery may be ineffective in preventing this movement. Utilizing this information, we engineered an envelope that locks the apex loop contacts to the adjacent protomer. This modification resulted in significant angle-of-approach shifts in the interaction of a neutralizing antibody. Our findings imply that blocking the intermediate state could be crucial for inducing antibodies with the appropriate bound state orientation through vaccination.

6.
Nat Commun ; 14(1): 2782, 2023 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-37188681

RESUMO

Antibody affinity maturation enables adaptive immune responses to a wide range of pathogens. In some individuals broadly neutralizing antibodies develop to recognize rapidly mutating pathogens with extensive sequence diversity. Vaccine design for pathogens such as HIV-1 and influenza has therefore focused on recapitulating the natural affinity maturation process. Here, we determine structures of antibodies in complex with HIV-1 Envelope for all observed members and ancestral states of the broadly neutralizing HIV-1 V3-glycan targeting DH270 antibody clonal B cell lineage. These structures track the development of neutralization breadth from the unmutated common ancestor and define affinity maturation at high spatial resolution. By elucidating contacts mediated by key mutations at different stages of antibody development we identified sites on the epitope-paratope interface that are the focus of affinity optimization. Thus, our results identify bottlenecks on the path to natural affinity maturation and reveal solutions for these that will inform immunogen design aimed at eliciting a broadly neutralizing immune response by vaccination.


Assuntos
Infecções por HIV , HIV-1 , Humanos , Infecções por HIV/prevenção & controle , HIV-1/genética , Anticorpos Neutralizantes , Anticorpos Anti-HIV , Polissacarídeos
7.
iScience ; 26(1): 105855, 2023 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-36590900

RESUMO

The COVID-19 pandemic, caused by the SARS-CoV-2 virus, has triggered myriad efforts to understand the structure and dynamics of this complex pathogen. The spike glycoprotein of SARS-CoV-2 is a significant target for immunogens as it is the means by which the virus enters human cells, while simultaneously sporting mutations responsible for immune escape. These functional and escape processes are regulated by complex molecular-level interactions. Our study presents quantitative insights on domain and residue contributions to allosteric communication, immune evasion, and local- and global-level control of functions through the derivation of a weighted graph representation from all-atom MD simulations. Focusing on the ancestral form and the D614G-variant, we provide evidence of the utility of our approach by guiding the selection of a mutation that alters the spike's stability. Taken together, the network approach serves as a valuable tool to evaluate communication "hot-spots" in proteins to guide design of stable immunogens.

8.
bioRxiv ; 2023 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-38187726

RESUMO

Immunization with mRNA or viral vectors encoding spike with diproline substitutions (S-2P) has provided protective immunity against severe COVID-19 disease. How immunization with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) spike elicits neutralizing antibodies (nAbs) against difficult-to-neutralize variants of concern (VOCs) remains an area of great interest. Here, we compare immunization of macaques with mRNA vaccines expressing ancestral spike either including or lacking diproline substitutions, and show the diproline substitutions were not required for protection against SARS-CoV-2 challenge or induction of broadly neutralizing B cell lineages. One group of nAbs elicited by the ancestral spike lacking diproline substitutions targeted the outer face of the receptor binding domain (RBD), neutralized all tested SARS-CoV-2 VOCs including Omicron XBB.1.5, but lacked cross-Sarbecovirus neutralization. Structural analysis showed that the macaque broad SARS-CoV-2 VOC nAbs bound to the same epitope as a human broad SARS-CoV-2 VOC nAb, DH1193. Vaccine-induced antibodies that targeted the RBD inner face neutralized multiple Sarbecoviruses, protected mice from bat CoV RsSHC014 challenge, but lacked Omicron variant neutralization. Thus, ancestral SARS-CoV-2 spike lacking proline substitutions encoded by nucleoside-modified mRNA can induce B cell lineages binding to distinct RBD sites that either broadly neutralize animal and human Sarbecoviruses or recent Omicron VOCs.

9.
bioRxiv ; 2023 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-38168268

RESUMO

Vaccine development targeting rapidly evolving pathogens such as HIV-1 requires induction of broadly neutralizing antibodies (bnAbs) with conserved paratopes and mutations, and, in some cases, the same Ig-heavy chains. The current trial-and-error search for immunogen modifications that improve selection for specific bnAb mutations is imprecise. To precisely engineer bnAb boosting immunogens, we used molecular dynamics simulations to examine encounter states that form when antibodies collide with the HIV-1 Envelope (Env). By mapping how bnAbs use encounter states to find their bound states, we identified Env mutations that were predicted to select for specific antibody mutations in two HIV-1 bnAb B cell lineages. The Env mutations encoded antibody affinity gains and selected for desired antibody mutations in vivo. These results demonstrate proof-of-concept that Env immunogens can be designed to directly select for specific antibody mutations at residue-level precision by vaccination, thus demonstrating the feasibility of sequential bnAb-inducing HIV-1 vaccine design.

10.
Cell Rep ; 39(13): 111009, 2022 06 28.
Artigo em Inglês | MEDLINE | ID: mdl-35732171

RESUMO

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron BA.2 sub-lineage has gained in proportion relative to BA.1. Because spike (S) protein variations may underlie differences in their pathobiology, here we determine cryoelectron microscopy (cryo-EM) structures of the BA.2 S ectodomain and compare these with previously determined BA.1 S structures. BA.2 receptor-binding domain (RBD) mutations induce remodeling of the RBD structure, resulting in tighter packing and improved thermostability. Interprotomer RBD interactions are enhanced in the closed (or 3-RBD-down) BA.2 S, while the fusion peptide is less accessible to antibodies than in BA.1. Binding and pseudovirus neutralization assays reveal extensive immune evasion while defining epitopes of two outer RBD face-binding antibodies, DH1044 and DH1193, that neutralize both BA.1 and BA.2. Taken together, our results indicate that stabilization of the closed state through interprotomer RBD-RBD packing is a hallmark of the Omicron variant and show differences in key functional regions in the BA.1 and BA.2 S proteins.


Assuntos
COVID-19 , SARS-CoV-2 , Anticorpos Antivirais , Microscopia Crioeletrônica , Humanos , Receptores Virais/metabolismo , Glicoproteína da Espícula de Coronavírus
11.
Mol Cell ; 82(11): 2050-2068.e6, 2022 06 02.
Artigo em Inglês | MEDLINE | ID: mdl-35447081

RESUMO

Aided by extensive spike protein mutation, the SARS-CoV-2 Omicron variant overtook the previously dominant Delta variant. Spike conformation plays an essential role in SARS-CoV-2 evolution via changes in receptor-binding domain (RBD) and neutralizing antibody epitope presentation, affecting virus transmissibility and immune evasion. Here, we determine cryo-EM structures of the Omicron and Delta spikes to understand the conformational impacts of mutations in each. The Omicron spike structure revealed an unusually tightly packed RBD organization with long range impacts that were not observed in the Delta spike. Binding and crystallography revealed increased flexibility at the functionally critical fusion peptide site in the Omicron spike. These results reveal a highly evolved Omicron spike architecture with possible impacts on its high levels of immune evasion and transmissibility.


Assuntos
COVID-19 , SARS-CoV-2 , Enzima de Conversão de Angiotensina 2 , Humanos , Mutação , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/química
12.
Cell Rep ; 38(11): 110514, 2022 03 15.
Artigo em Inglês | MEDLINE | ID: mdl-35294883

RESUMO

The success of nucleoside-modified mRNAs in lipid nanoparticles (mRNA-LNP) as COVID-19 vaccines heralded a new era of vaccine development. For HIV-1, multivalent envelope (Env) trimer protein nanoparticles are superior immunogens compared with trimers alone for priming of broadly neutralizing antibody (bnAb) B cell lineages. The successful expression of complex multivalent nanoparticle immunogens with mRNAs has not been demonstrated. Here, we show that mRNAs can encode antigenic Env trimers on ferritin nanoparticles that initiate bnAb precursor B cell expansion and induce serum autologous tier 2 neutralizing activity in bnAb precursor VH + VL knock-in mice. Next-generation sequencing demonstrates acquisition of critical mutations, and monoclonal antibodies that neutralize heterologous HIV-1 isolates are isolated. Thus, mRNA-LNP can encode complex immunogens and may be of use in design of germline-targeting and sequential boosting immunogens for HIV-1 vaccine development.


Assuntos
Vacinas contra a AIDS , COVID-19 , HIV-1 , Nanopartículas , Animais , Anticorpos Monoclonais , Anticorpos Neutralizantes , Vacinas contra COVID-19 , Epitopos , Ferritinas/genética , Anticorpos Anti-HIV , Humanos , Lipossomos , Camundongos , RNA Mensageiro , Produtos do Gene env do Vírus da Imunodeficiência Humana/genética
13.
bioRxiv ; 2022 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-35118469

RESUMO

Aided by extensive spike protein mutation, the SARS-CoV-2 Omicron variant overtook the previously dominant Delta variant. Spike conformation plays an essential role in SARS-CoV-2 evolution via changes in receptor binding domain (RBD) and neutralizing antibody epitope presentation affecting virus transmissibility and immune evasion. Here, we determine cryo-EM structures of the Omicron and Delta spikes to understand the conformational impacts of mutations in each. The Omicron spike structure revealed an unusually tightly packed RBD organization with long range impacts that were not observed in the Delta spike. Binding and crystallography revealed increased flexibility at the functionally critical fusion peptide site in the Omicron spike. These results reveal a highly evolved Omicron spike architecture with possible impacts on its high levels of immune evasion and transmissibility.

14.
Cell Rep ; 37(5): 109922, 2021 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-34731616

RESUMO

Recognition of N-linked glycan at residue N276 (glycan276) at the periphery of the CD4-binding site (CD4bs) on the HIV-envelope trimer is a formidable challenge for many CD4bs-directed antibodies. To understand how this glycan can be recognized, here we isolate two lineages of glycan276-dependent CD4bs antibodies. Antibody CH540-VRC40.01 (named for donor-lineage.clone) neutralizes 81% of a panel of 208 diverse strains, while antibody CH314-VRC33.01 neutralizes 45%. Cryo-electron microscopy (cryo-EM) structures of these two antibodies and 179NC75, a previously identified glycan276-dependent CD4bs antibody, in complex with HIV-envelope trimer reveal substantially different modes of glycan276 recognition. Despite these differences, binding of glycan276-dependent antibodies maintains a glycan276 conformation similar to that observed in the absence of glycan276-binding antibodies. By contrast, glycan276-independent CD4bs antibodies, such as VRC01, displace glycan276 upon binding. These results provide a foundation for understanding antibody recognition of glycan276 and suggest its presence may be crucial for priming immunogens seeking to initiate broad CD4bs recognition.


Assuntos
Vacinas contra a AIDS/imunologia , Anticorpos Amplamente Neutralizantes/imunologia , Epitopos , HIV-1/imunologia , Polissacarídeos/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Vacinas contra a AIDS/metabolismo , Especificidade de Anticorpos , Sítios de Ligação de Anticorpos , Anticorpos Amplamente Neutralizantes/metabolismo , Anticorpos Amplamente Neutralizantes/ultraestrutura , Antígenos CD4/imunologia , Antígenos CD4/metabolismo , Microscopia Crioeletrônica , Células HEK293 , HIV-1/metabolismo , Humanos , Modelos Moleculares , Polissacarídeos/metabolismo , Ligação Proteica , Conformação Proteica , Imagem Individual de Molécula , Relação Estrutura-Atividade , Produtos do Gene env do Vírus da Imunodeficiência Humana/metabolismo
15.
bioRxiv ; 2021 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-34401876

RESUMO

The success of nucleoside-modified mRNAs in lipid nanoparticles (mRNA-LNP) as COVID-19 vaccines heralded a new era of vaccine development. For HIV-1, multivalent envelope (Env) trimer protein nanoparticles are superior immunogens compared to trimers alone for priming of broadly neutralizing antibody (bnAb) B cell lineages. The successful expression of complex multivalent nanoparticle immunogens with mRNAs has not been demonstrated. Here we show that mRNAs can encode antigenic Env trimers on ferritin nanoparticles that initiate bnAb precursor B cell expansion and induce serum autologous tier 2 neutralizing activity in bnAb precursor VH + VL knock-in mice. Next generation sequencing demonstrated acquisition of critical mutations, and monoclonal antibodies that neutralized heterologous HIV-1 isolates were isolated. Thus, mRNA-LNP can encode complex immunogens and are of use in design of germline-targeting and sequential boosting immunogens for HIV-1 vaccine development.

16.
Viruses ; 13(5)2021 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-34067073

RESUMO

The HIV-1 envelope glycoprotein (Env) mediates host cell fusion and is the primary target for HIV-1 vaccine design. The Env undergoes a series of functionally important conformational rearrangements upon engagement of its host cell receptor, CD4. As the sole target for broadly neutralizing antibodies, our understanding of these transitions plays a critical role in vaccine immunogen design. Here, we review available experimental data interrogating the HIV-1 Env conformation and detail computational efforts aimed at delineating the series of conformational changes connecting these rearrangements. These studies have provided a structural mapping of prefusion closed, open, and transition intermediate structures, the allosteric elements controlling rearrangements, and state-to-state transition dynamics. The combination of these investigations and innovations in molecular modeling set the stage for advanced studies examining rearrangements at greater spatial and temporal resolution.


Assuntos
Proteína gp41 do Envelope de HIV/química , HIV-1/genética , Produtos do Gene env do Vírus da Imunodeficiência Humana/química , Produtos do Gene env do Vírus da Imunodeficiência Humana/metabolismo , Anticorpos Neutralizantes/imunologia , Anticorpos Anti-HIV/imunologia , Proteína gp41 do Envelope de HIV/genética , Proteína gp41 do Envelope de HIV/imunologia , HIV-1/química , HIV-1/imunologia , Modelos Moleculares , Ligação Proteica , Conformação Proteica , Multimerização Proteica , Internalização do Vírus , Produtos do Gene env do Vírus da Imunodeficiência Humana/genética , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia
17.
Science ; 373(6555)2021 08 06.
Artigo em Inglês | MEDLINE | ID: mdl-34168071

RESUMO

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants with multiple spike mutations enable increased transmission and antibody resistance. We combined cryo-electron microscopy (cryo-EM), binding, and computational analyses to study variant spikes, including one that was involved in transmission between minks and humans, and others that originated and spread in human populations. All variants showed increased angiotensin-converting enzyme 2 (ACE2) receptor binding and increased propensity for receptor binding domain (RBD)-up states. While adaptation to mink resulted in spike destabilization, the B.1.1.7 (UK) spike balanced stabilizing and destabilizing mutations. A local destabilizing effect of the RBD E484K mutation was implicated in resistance of the B.1.1.28/P.1 (Brazil) and B.1.351 (South Africa) variants to neutralizing antibodies. Our studies revealed allosteric effects of mutations and mechanistic differences that drive either interspecies transmission or escape from antibody neutralization.


Assuntos
SARS-CoV-2/química , SARS-CoV-2/genética , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética , Substituição de Aminoácidos , Enzima de Conversão de Angiotensina 2/metabolismo , Animais , Anticorpos Neutralizantes/imunologia , Anticorpos Antivirais/imunologia , Antígenos Virais/imunologia , COVID-19/transmissão , COVID-19/veterinária , COVID-19/virologia , Microscopia Crioeletrônica , Adaptação ao Hospedeiro , Humanos , Evasão da Resposta Imune , Vison/virologia , Modelos Moleculares , Mutação , Ligação Proteica , Conformação Proteica , Domínios e Motivos de Interação entre Proteínas , Estrutura Quaternária de Proteína , Subunidades Proteicas/química , Receptores de Coronavírus/metabolismo , SARS-CoV-2/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Glicoproteína da Espícula de Coronavírus/metabolismo
18.
Cell ; 184(11): 2955-2972.e25, 2021 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-34019795

RESUMO

Natural antibodies (Abs) can target host glycans on the surface of pathogens. We studied the evolution of glycan-reactive B cells of rhesus macaques and humans using glycosylated HIV-1 envelope (Env) as a model antigen. 2G12 is a broadly neutralizing Ab (bnAb) that targets a conserved glycan patch on Env of geographically diverse HIV-1 strains using a unique heavy-chain (VH) domain-swapped architecture that results in fragment antigen-binding (Fab) dimerization. Here, we describe HIV-1 Env Fab-dimerized glycan (FDG)-reactive bnAbs without VH-swapped domains from simian-human immunodeficiency virus (SHIV)-infected macaques. FDG Abs also recognized cell-surface glycans on diverse pathogens, including yeast and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike. FDG precursors were expanded by glycan-bearing immunogens in macaques and were abundant in HIV-1-naive humans. Moreover, FDG precursors were predominately mutated IgM+IgD+CD27+, thus suggesting that they originated from a pool of antigen-experienced IgM+ or marginal zone B cells.


Assuntos
Anticorpos Neutralizantes/imunologia , HIV-1/imunologia , Fragmentos Fab das Imunoglobulinas/imunologia , Polissacarídeos/imunologia , SARS-CoV-2/imunologia , Vírus da Imunodeficiência Símia/imunologia , Glicoproteína da Espícula de Coronavírus/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/imunologia , Animais , Linfócitos B/imunologia , Anticorpos Amplamente Neutralizantes/imunologia , COVID-19/imunologia , Dimerização , Epitopos/imunologia , Glicosilação , Anticorpos Anti-HIV/imunologia , Infecções por HIV/imunologia , Humanos , Fragmentos Fab das Imunoglobulinas/química , Macaca mulatta , Polissacarídeos/química , Receptores de Antígenos de Linfócitos B/química , Vírus da Imunodeficiência Símia/genética , Vacinas/imunologia , Produtos do Gene env do Vírus da Imunodeficiência Humana/química , Produtos do Gene env do Vírus da Imunodeficiência Humana/genética
19.
bioRxiv ; 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33758838

RESUMO

New SARS-CoV-2 variants that have accumulated multiple mutations in the spike (S) glycoprotein enable increased transmission and resistance to neutralizing antibodies. Here, we study the antigenic and structural impacts of the S protein mutations from four variants, one that was involved in transmission between minks and humans, and three that rapidly spread in human populations and originated in the United Kingdom, Brazil or South Africa. All variants either retained or improved binding to the ACE2 receptor. The B.1.1.7 (UK) and B.1.1.28 (Brazil) spike variants showed reduced binding to neutralizing NTD and RBD antibodies, respectively, while the B.1.351 (SA) variant showed reduced binding to both NTD- and RBD-directed antibodies. Cryo-EM structural analyses revealed allosteric effects of the mutations on spike conformations and revealed mechanistic differences that either drive inter-species transmission or promotes viral escape from dominant neutralizing epitopes. HIGHLIGHTS: Cryo-EM structures reveal changes in SARS-CoV-2 S protein during inter-species transmission or immune evasion.Adaptation to mink resulted in increased ACE2 binding and spike destabilization.B.1.1.7 S mutations reveal an intricate balance of stabilizing and destabilizing effects that impact receptor and antibody binding.E484K mutation in B.1.351 and B.1.1.28 S proteins drives immune evasion by altering RBD conformation.S protein uses different mechanisms to converge upon similar solutions for altering RBD up/down positioning.

20.
Cell Rep ; 34(2): 108630, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33417835

RESUMO

The severe acute respiratory coronavirus 2 (SARS-CoV-2) spike (S) protein is the target of vaccine design efforts to end the coronavirus disease 2019 (COVID-19) pandemic. Despite a low mutation rate, isolates with the D614G substitution in the S protein appeared early during the pandemic and are now the dominant form worldwide. Here, we explore S conformational changes and the effects of the D614G mutation on a soluble S ectodomain construct. Cryoelectron microscopy (cryo-EM) structures reveal altered receptor binding domain (RBD) disposition; antigenicity and proteolysis experiments reveal structural changes and enhanced furin cleavage efficiency of the G614 variant. Furthermore, furin cleavage alters the up/down ratio of the RBDs in the G614 S ectodomain, demonstrating an allosteric effect on RBD positioning triggered by changes in the SD2 region, which harbors residue 614 and the furin cleavage site. Our results elucidate SARS-CoV-2 S conformational landscape and allostery and have implications for vaccine design.


Assuntos
Peptídeo Hidrolases/metabolismo , SARS-CoV-2/metabolismo , Glicoproteína da Espícula de Coronavírus/metabolismo , COVID-19/patologia , COVID-19/virologia , Microscopia Crioeletrônica , Humanos , Imunogenicidade da Vacina , Simulação de Dinâmica Molecular , Mutação , Domínios Proteicos , Estabilidade Proteica , Estrutura Quaternária de Proteína , Subunidades Proteicas/metabolismo , Proteólise , SARS-CoV-2/isolamento & purificação , Glicoproteína da Espícula de Coronavírus/química , Glicoproteína da Espícula de Coronavírus/genética
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