scholarly journals Conformational dynamics of the Beta and Kappa SARS-CoV-2 spike proteins and their complexes with ACE2 receptor revealed by cryo-EM

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yifan Wang ◽  
Cong Xu ◽  
Yanxing Wang ◽  
Qin Hong ◽  
Chao Zhang ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Biochemical Analysis ◽  
Conformational Dynamics ◽  
Viral Fusion ◽  
Immune Evasion Mechanism ◽  
Binding Surface ◽  
Structural Nature ◽  
Conformational Landscape ◽  
Population Shift ◽  
Kinetics Of

AbstractThe emergence of SARS-CoV-2 Kappa and Beta variants with enhanced transmissibility and resistance to neutralizing antibodies has created new challenges for the control of the ongoing COVID-19 pandemic. Understanding the structural nature of Kappa and Beta spike (S) proteins and their association with ACE2 is of significant importance. Here we present two cryo-EM structures for each of the Kappa and Beta spikes in the open and open-prone transition states. Compared with wild-type (WT) or G614 spikes, the two variant spikes appear more untwisted/open especially for Beta, and display a considerable population shift towards the open state as well as more pronounced conformational dynamics. Moreover, we capture four conformational states of the S-trimer/ACE2 complex for each of the two variants, revealing an enlarged conformational landscape for the Kappa and Beta S-ACE2 complexes and pronounced population shift towards the three RBDs up conformation. These results implicate that the mutations in Kappa and Beta may modify the kinetics of receptor binding and viral fusion to improve virus fitness. Combined with biochemical analysis, our structural study shows that the two variants are enabled to efficiently interact with ACE2 receptor despite their sensitive ACE2 binding surface is modified to escape recognition by some potent neutralizing MAbs. Our findings shed new light on the pathogenicity and immune evasion mechanism of the Beta and Kappa variants.

scholarly journals Real-Time Analysis of Individual Ebola Virus Glycoproteins Reveals Pre-Fusion, Entry-Relevant Conformational Dynamics

Viruses ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 103 ◽  
Author(s):  
Natasha D. Durham ◽  
Angela R. Howard ◽  
Ramesh Govindan ◽  
Fernando Senjobe ◽  
J. Maximilian Fels ◽  
...  
Keyword(s):  
Single Molecule ◽  
Conformational Changes ◽  
Neutralizing Antibodies ◽  
Ebola Virus ◽  
Transmembrane Protein ◽  
Conformational Dynamics ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Target Cells ◽  
Viral Fusion

The Ebola virus (EBOV) envelope glycoprotein (GP) mediates the fusion of the virion membrane with the membrane of susceptible target cells during infection. While proteolytic cleavage of GP by endosomal cathepsins and binding of the cellular receptor Niemann-Pick C1 protein (NPC1) are essential steps for virus entry, the detailed mechanisms by which these events promote membrane fusion remain unknown. Here, we applied single-molecule Förster resonance energy transfer (smFRET) imaging to investigate the structural dynamics of the EBOV GP trimeric ectodomain, and the functional transmembrane protein on the surface of pseudovirions. We show that in both contexts, pre-fusion GP is dynamic and samples multiple conformations. Removal of the glycan cap and NPC1 binding shift the conformational equilibrium, suggesting stabilization of conformations relevant to viral fusion. Furthermore, several neutralizing antibodies enrich alternative conformational states. This suggests that these antibodies neutralize EBOV by restricting access to GP conformations relevant to fusion. This work demonstrates previously unobserved dynamics of pre-fusion EBOV GP and presents a platform with heightened sensitivity to conformational changes for the study of GP function and antibody-mediated neutralization.

scholarly journals Kinetics of Neutralizing Antibodies of COVID-19 Patients Tested Using Clinical D614G, B.1.1.7 and B 1.351 Isolates in Microneutralization Assays

Viruses ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 996
Author(s):  
Jenni Virtanen ◽  
Ruut Uusitalo ◽  
Essi M. Korhonen ◽  
Kirsi Aaltonen ◽  
Teemu Smura ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Acute Infection ◽  
Clinical Isolates ◽  
Wild Type Virus ◽  
Type Virus ◽  
Wild Type ◽  
Kinetics Of

Increasing evidence suggests that some newly emerged SARS-CoV-2 variants of concern (VoCs) resist neutralization by antibodies elicited by the early-pandemic wild-type virus. We applied neutralization tests to paired recoveree sera (n = 38) using clinical isolates representing the first wave (D614G), VoC1, and VoC2 lineages (B.1.1.7 and B 1.351). Neutralizing antibodies inhibited contemporary and VoC1 lineages, whereas inhibition of VoC2 was reduced 8-fold, with 50% of sera failing to show neutralization. These results provide evidence for the increased potential of VoC2 to reinfect previously SARS-CoV-infected individuals. The kinetics of NAbs in different patients showed similar decline against all variants, with generally low initial anti-B.1.351 responses becoming undetectable, but with anti-B.1.1.7 NAbs remaining detectable (>20) for months after acute infection.

scholarly journals Kinetics of Anti-SARS-CoV-2 Antibody Responses 3 Months Post Complete Vaccination with BNT162b2; A Prospective Study in 283 Health Workers

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 1942
Author(s):  
Evangelos Terpos ◽  
Ioannis P. Trougakos ◽  
Vangelis Karalis ◽  
Ioannis Ntanasis-Stathopoulos ◽  
Sentiljana Gumeni ◽  
...  
Keyword(s):  
Neutralizing Antibodies ◽  
Health Workers ◽  
Antibody Responses ◽  
Healthy Individuals ◽  
Younger Age ◽  
Constant Rate ◽  
Rate Of Decline ◽  
A Prospective Study ◽  
Kinetics Of ◽  
Over Time

The aim of this study was to investigate the kinetics of neutralizing antibodies (NAbs) and anti-SARS-CoV-2 anti-S-RBD IgGs up to three months after the second vaccination dose with the BNT162b2 mRNA vaccine. NAbs and anti-S-RBD levels were measured on days 1 (before the first vaccine shot), 8, 22 (before the second shot), 36, 50, and three months after the second vaccination (D111) (NCT04743388). 283 health workers were included in this study. NAbs showed a rapid increase from D8 to D36 at a constant rate of about 3% per day and reached a median (SD) of 97.2% (4.7) at D36. From D36 to D50, a slight decrease in NAbs values was detected and it became more prominent between D50 and D111 when the rate of decline was determined at −0.11 per day. The median (SD) NAbs value at D111 was 92.7% (11.8). A similar pattern was also observed for anti-S-RBD antibodies. Anti-S-RBDs showed a steeper increase during D22–D36 and a lower decline rate during D36–D111. Prior COVID-19 infection and younger age were associated with superior antibody responses over time. In conclusion, we found a persistent but declining anti-SARS-CoV-2 humoral immunity at 3 months following full vaccination with BNT162b2 in healthy individuals.

Conformational dynamics and pre-steady-state kinetics of DNA glycosylases

2010 ◽  
Vol 75 (10) ◽  
pp. 1225-1239 ◽  
Author(s):  
O. S. Fedorova ◽  
N. A. Kuznetsov ◽  
V. V. Koval ◽  
D. G. Knorre
Keyword(s):  
Steady State ◽  
Conformational Dynamics ◽  
Dna Glycosylases ◽  
Steady State Kinetics ◽  
Kinetics Of

scholarly journals Declining Levels of Neutralizing Antibodies Against SARS-CoV-2 in Convalescent COVID-19 Patients One Year Post Symptom Onset

2021 ◽  
Vol 12 ◽  
Author(s):  
Tiandan Xiang ◽  
Boyun Liang ◽  
Yaohui Fang ◽  
Sihong Lu ◽  
Sumeng Li ◽  
...  
Keyword(s):  
Symptom Onset ◽  
Neutralizing Antibodies ◽  
Natural Infection ◽  
Protein S ◽  
Igg Antibodies ◽  
Neutralizing Activity ◽  
Specific Igg ◽  
One Year ◽  
Kinetics Of

Major advances have been made in understanding the dynamics of humoral immunity briefly after the acute coronavirus disease 2019 (COVID-19). However, knowledge concerning long-term kinetics of antibody responses in convalescent patients is limited. During a one-year period post symptom onset, we longitudinally collected 162 samples from 76 patients and quantified IgM and IgG antibodies recognizing the nucleocapsid (N) protein or the receptor binding domain (RBD) of the spike protein (S). After one year, approximately 90% of recovered patients still had detectable SARS-CoV-2-specific IgG antibodies recognizing N and RBD-S. Intriguingly, neutralizing activity was only detectable in ~43% of patients. When neutralization tests against the E484K-mutated variant of concern (VOC) B.1.351 (initially identified in South Africa) were performed among patients who neutralize the original virus, the capacity to neutralize was even further diminished to 22.6% of donors. Despite declining N- and S-specific IgG titers, a considerable fraction of recovered patients had detectable neutralizing activity one year after infection. However, neutralizing capacities, in particular against an E484K-mutated VOC were only detectable in a minority of patients one year after symptomatic COVID-19. Our findings shed light on the kinetics of long-term immune responses after natural SARS-CoV-2 infection and argue for vaccinations of individuals who experienced a natural infection to protect against emerging VOC.

scholarly journals Oversized galactosides as a probe for conformational dynamics in LacY

2018 ◽  
Vol 115 (16) ◽  
pp. 4146-4151 ◽  
Author(s):  
Irina Smirnova ◽  
Vladimir Kasho ◽  
Xiaoxu Jiang ◽  
Hong-Ming Chen ◽  
Stephen G. Withers ◽  
...  
Keyword(s):  
Binding Site ◽  
Conformational Dynamics ◽  
Dissociation Rate ◽  
Binding Kinetics ◽  
Lactose Permease ◽  
E Coli ◽  
Open Conformation ◽  
Dissociation Rate Constants ◽  
Kinetics Of ◽  
Micromolar Range

Binding kinetics of α-galactopyranoside homologs with fluorescent aglycones of different sizes and shapes were determined with the lactose permease (LacY) of Escherichia coli by FRET from Trp151 in the binding site of LacY to the fluorophores. Fast binding was observed with LacY stabilized in an outward-open conformation (kon = 4–20 μM−1·s−1), indicating unobstructed access to the binding site even for ligands that are much larger than lactose. Dissociation rate constants (koff) increase with the size of the aglycone so that Kd values also increase but remain in the micromolar range for each homolog. Phe27 (helix I) forms an apparent constriction in the pathway for sugar by protruding into the periplasmic cavity. However, replacement of Phe27 with a bulkier Trp does not create an obstacle in the pathway even for large ligands, since binding kinetics remain unchanged. High accessibility of the binding site is also observed in a LacY/nanobody complex with partially blocked periplasmic opening. Remarkably, E. coli expressing WT LacY catalyzes transport of α- or β-galactopyranosides with oversized aglycones such as bodipy or Aldol518, which may require an extra space within the occluded intermediate. The results confirm that LacY specificity is strictly directed toward the galactopyranoside ring and also clearly indicate that the opening on the periplasmic side is sufficiently wide to accommodate the large galactoside derivatives tested here. We conclude that the actual pathway for the substrate entering from the periplasmic side is wider than the pore diameter calculated in the periplasmic-open X-ray structures.

Keratinocyte growth regulation in fibroblast cocultures via a double paracrine mechanism

1999 ◽  
Vol 112 (12) ◽  
pp. 1843-1853 ◽  
Author(s):  
N. Maas-Szabowski ◽  
A. Shimotoyodome ◽  
N.E. Fusenig
Keyword(s):  
Neutralizing Antibodies ◽  
Growth Regulation ◽  
Keratinocyte Growth Factor ◽  
Dermal Fibroblasts ◽  
Tissue Homeostasis ◽  
Epidermal Keratinocytes ◽  
Human Epidermal Keratinocytes ◽  
Keratinocyte Proliferation ◽  
Normal Human ◽  
Kinetics Of

Epithelial-mesenchymal interactions play an important role in regulating tissue homeostasis and repair. For skin, the regulatory mechanisms of epidermal-dermal interactions were studied in cocultures of normal human epidermal keratinocytes (NEK) and dermal fibroblasts (HDF) rendered postmitotic by alpha-irradiation (HDFi). The expression kinetics of different cytokines and their receptors with presumed signalling function in skin were determined at the RNA and protein level in mono- and cocultured NEK and HDFi. In cocultured HDFi, mRNA and protein synthesis of keratinocyte growth factor (KGF) (FGF-7) was strongly enhanced, whereas in cocultured keratinocytes interleukin (IL)-1alpha and -1beta mRNA expression increased compared to monocultures. Thus we postulated that IL-1, which had no effect on keratinocyte proliferation, induced in fibroblasts the expression of factors stimulating keratinocyte proliferation, such as KGF. The functional significance of this reciprocal modulation was substantiated by blocking experiments. Both IL-1alpha and -1beta-neutralizing antibodies and IL-1 receptor antagonist significantly reduced keratinocyte proliferation supposedly through abrogation of KGF production, because IL-1 antibodies blocked the induced KGF production. These data indicate a regulation of keratinocyte growth by a double paracrine mechanism through release of IL-1 which induces KGF in cocultured fibroblasts. Thus IL-1, in addition to its proinflammatory function in skin, may play an essential role in regulating tissue homeostasis.

HTLV-II down-regulates HIV-1 replication in IL-2–stimulated primary PBMC of coinfected individuals through expression of MIP-1α

Blood ◽  
2000 ◽  
Vol 95 (9) ◽  
pp. 2760-2769 ◽  
Author(s):  
Claudio Casoli ◽  
Elisa Vicenzi ◽  
Andrea Cimarelli ◽  
Giacomo Magnani ◽  
Paolo Ciancianaini ◽  
...  
Keyword(s):  
T Cells ◽  
Neutralizing Antibodies ◽  
Ex Vivo ◽  
Interleukin 2 ◽  
Peripheral Blood Mononuclear ◽  
Human T Cell ◽  
Cc Chemokines ◽  
Kinetics Of ◽  
Hiv 1

The influence of human T-cell leukemia/lymphoma virus type II (HTLV-II) in individuals also infected with HIV-1 is poorly understood. To evaluate the reciprocal influence of HTLV-II and HIV-1 infection, primary peripheral blood mononuclear cell (PBMC) cultures from coinfected individuals were established in the presence of interleukin 2 (IL-2). In these cultures, the kinetics of HTLV-II replication always preceded those of HIV-1. Noteworthy, the kinetics of HIV-1 production were inversely correlated to the HTLV-II proviral load in vivo and its replication ex vivo. These observations suggested a potential interaction between the 2 retroviruses. In this regard, the levels of IL-2, IL-6, and tumor necrosis factor- (TNF-) were measured in the same coinfected PBMC cultures. Endogenous IL-2 was not produced, whereas IL-6 and TNF- were secreted at levels compatible with their known ability to up-regulate HIV-1 expression. The HIV-suppressive CC-chemokines RANTES, macrophage inflammatory protein-1 (MIP-1), and MIP-1β were also determined in IL-2–stimulated PBMC cultures. Of interest, their kinetics and concentrations were inversely related to those of HIV-1 replication. Experiments were performed in which CD8+ T cells or PBMCs from HTLV-II monoinfected individuals were cocultivated with CD4+ T cells from HIV-1 monoinfected individuals separated by a semipermeable membrane in the presence or absence of antichemokine neutralizing antibodies. The results indicate that HTLV-II can interfere with the replicative potential of HIV-1 by up-regulating viral suppressive CC-chemokines and, in particular, MIP-1. This study is the first report indicating that HTLV-II can influence HIV replication, at least in vitro, via up-regulation of HIV-suppressive chemokines.

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