Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 64
Filtrar
1.
Virus Res ; 345: 199376, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38643856

RESUMO

Zika virus (ZIKV) and Japanese encephalitis virus (JEV) are antigenically related flaviviruses that co-circulate in many countries/territories. The interaction between the two viruses needs to be determined. Recent findings by ourselves and other labs showed that JEV-elicited antibodies (Abs) and CD8+T cells exacerbate and protect against subsequent ZIKV infection, respectively. However, the impact of JEV envelope (E) protein domain III (EDIII)-induced immune responses on ZIKV infection is unclear. We show here that sera from JEV-EDIII-vaccinated mice cross-react with ZIKV-EDIII in vitro, and transfer of the same sera to mice significantly decreases death upon lethal ZIKV infection at a dose-dependent manner. Maternally acquired anti-JEV-EDIII Abs also significantly reduce the mortality of neonatal mice born to JEV-EDIII-immune mothers post ZIKV challenge. Similarly, transfer of ZIKV-EDIII-reactive IgG purified from JEV-vaccinated humans increases the survival of ZIKV-infected mice. Notably, transfer of an extremely low volume of JEV-EDIII-immune sera or ZIKV-EDIII-reactive IgG does not mediate the Ab-mediated enhancement (ADE) of ZIKV infection. Similarly, transfer of JEV-EDIII-elicited CD8+T cells protects recipient mice against ZIKV challenge. These results demonstrate that JEV-EDIII-induced immune components including Abs and T cells have protective roles in ZIKV infection, suggesting EDIII is a promising immunogen for developing effective and safety JEV vaccine.


Assuntos
Anticorpos Antivirais , Linfócitos T CD8-Positivos , Proteção Cruzada , Vírus da Encefalite Japonesa (Espécie) , Proteínas do Envelope Viral , Infecção por Zika virus , Zika virus , Animais , Infecção por Zika virus/prevenção & controle , Infecção por Zika virus/imunologia , Linfócitos T CD8-Positivos/imunologia , Zika virus/imunologia , Anticorpos Antivirais/imunologia , Anticorpos Antivirais/sangue , Proteínas do Envelope Viral/imunologia , Camundongos , Vírus da Encefalite Japonesa (Espécie)/imunologia , Proteção Cruzada/imunologia , Feminino , Reações Cruzadas , Encefalite Japonesa/prevenção & controle , Encefalite Japonesa/imunologia , Humanos , Imunoglobulina G/imunologia , Imunoglobulina G/sangue , Modelos Animais de Doenças , Imunização
2.
Front Cell Infect Microbiol ; 14: 1351993, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38524182

RESUMO

Acinetobacter baumannii (A. baumannii) is a popular clinical pathogen worldwide. Biofilm-associated antibiotic-resistant A. baumannii infection poses a great threat to human health. Bacteria in biofilms are highly resistant to antibiotics and disinfectants. Furthermore, inhibition or eradication of biofilms in husbandry, the food industry and clinics are almost impossible. Phages can move across the biofilm matrix and promote antibiotic penetration. In the present study, a lytic A. baumannii phage vB_AbaM-SHI, belonging to family Straboviridae, was isolated from sauce chop factory drain outlet in Wuxi, China. The DNA genome consists of 44,180 bp which contain 93 open reading frames, and genes encoding products morphogenesis are located at the end of the genome. The amino acid sequence of vB_AbaM-SHI endolysin is different from those of previously reported A. baumannii phages in NCBI. Phage vB_AbaM-SHI endolysin has two additional ß strands due to the replacement of a lysine (K) (in KU510289.1, NC_041857.1, JX976549.1 and MH853786.1) with an arginine (R) (SHI) at position 21 of A. baumannii phage endolysin. Spot test showed that phage vB_AbaM-SHI is able to lyse some antibiotic-resistant bacteria, such as A. baumannii (SL, SL1, and SG strains) and E. coli BL21 strain. Additionally, phage vB_AbaM-SHI independently killed bacteria and inhibited bacterial biofilm formation, and synergistically exerted strong antibacterial effects with antibiotics. This study provided a new perspective into the potential application value of phage vB_AbaM-SHI as an antimicrobial agent.


Assuntos
Acinetobacter baumannii , Bacteriófagos , Humanos , Bacteriófagos/genética , Escherichia coli , Antibacterianos/farmacologia , Biofilmes
3.
Nat Commun ; 14(1): 6093, 2023 Sep 29.
Artigo em Inglês | MEDLINE | ID: mdl-37773159

RESUMO

Magnon polarons are novel elementary excitations possessing hybrid magnonic and phononic signatures, and are responsible for many exotic spintronic and magnonic phenomena. Despite long-term sustained experimental efforts in chasing for magnon polarons, direct spectroscopic evidence of their existence is hardly observed. Here, we report the direct observation of magnon polarons using neutron spectroscopy on a multiferroic Fe2Mo3O8 possessing strong magnon-phonon coupling. Specifically, below the magnetic ordering temperature, a gap opens at the nominal intersection of the original magnon and phonon bands, leading to two separated magnon-polaron bands. Each of the bands undergoes mixing, interconverting and reversing between its magnonic and phononic components. We attribute the formation of magnon polarons to the strong magnon-phonon coupling induced by Dzyaloshinskii-Moriya interaction. Intriguingly, we find that the band-inverted magnon polarons are topologically nontrivial. These results uncover exotic elementary excitations arising from the magnon-phonon coupling, and offer a new route to topological states by considering hybridizations between different types of fundamental excitations.

4.
Adv Mater ; 35(36): e2302568, 2023 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-37285053

RESUMO

Fe3 GeTe2 have proven to be of greatly intrigue. However, the underlying mechanism behind the varying Curie temperature (Tc ) values remains a puzzle. This study explores the atomic structure of Fe3 GeTe2 crystals exhibiting Tc values of 160, 210, and 230 K. The elemental mapping reveals a Fe-intercalation on the interstitial sites within the van der Waals gap of the high-Tc (210 and 230 K) samples, which are observed to have an exchange bias effect by electrical transport measurements, while Fe intercalation or the bias effect is absent in the low-Tc (160 K) samples. First-principles calculations further suggest that the Fe-intercalation layer may be responsible for the local antiferromagnetic coupling that gives rise to the exchange bias effect, and that the interlayer exchange paths greatly contribute to the enhancement of Tc . This discovery of the Fe-intercalation layer elucidates the mechanism behind the hidden antiferromagnetic ordering that underlies the enhancement of Tc in Fe3 GeTe2 .

5.
Nano Lett ; 23(11): 5164-5170, 2023 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-37263581

RESUMO

Topological defects are fundamental concepts in physics, but little is known about the transition between distinct types across different dimensionalities. In topological magnetism, as in field theory, the transition between 1D strings and 0D monopoles is a key process whose observation has remained elusive. Here, we introduce a novel mechanism that allows for the controlled stabilization of emergent monopoles and show that magnetic skyrmion strings can be folded into monopoles. Conversely, they act as seeds out of which the entire string structure can unfold, containing its complete information. In chiral magnets, this process can be observed by resonant elastic X-ray scattering when the objects are in proximity to a polarized ferromagnet, whereby a pure monopole lattice is emerging on the surface. Our experimental proof of the reversible evolution from monopole to string sheds new light on topological defects and establishes the emergent monopole lattice as a new 3D topological phase.

6.
Nat Nanotechnol ; 18(8): 854-860, 2023 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-37169899

RESUMO

Hysteretic switching of domain states is a salient characteristic of all ferroic materials and the foundation for their multifunctional applications. Ferro-rotational order is emerging as a type of ferroic order that features structural rotations, but control over state switching remains elusive due to its invariance under both time reversal and spatial inversion. Here we demonstrate electrical switching of ferro-rotational domain states in the charge-density-wave phases of nanometre-thick 1T-TaS2 crystals. Cooling from the high-symmetry phase to the ferro-rotational phase under an external electric field induces domain state switching and domain wall formation, which is realized in a simple two-terminal configuration using a volt-scale bias. Although the electric field does not couple with the order due to symmetry mismatch, it drives domain wall propagation to give rise to reversible, durable and non-volatile isothermal state switching at room temperature. These results offer a route to the manipulation of ferro-rotational order and its nanoelectronic applications.

7.
Journal of Preventive Medicine ; (12): 677-681, 2023.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-980300

RESUMO

@#There are more than 70 species of flaviviruses, including Zika virus, Dengue virus and Japanese encephalitis virus, and more than 33 species are known to be capable of infecting humans. Only three flavivirus vaccines have been approved, and there is a lack of safe and effective vaccines for most flaviviruses. Adenovirus-vectored vaccines have high safety, low cost, and convenience to store and transport. Currently, two adenovirus-vectored Zika vaccines are under early clinical trials, and adenovirus-vectored vaccines for Dengue virus, Japanese encephalitis virus, West Nile virus and yellow fever virus are still in the phase of animal experiment. In the development of adenovirus-vectored flavivirus vaccines, there are still problems of pre-existing immunity to adenovirus, the insufficient immunogenicity of adenovirus vectors and the antibody-dependent enhancement effects among flavivirus. Based on relevant publications from January 2006 to June 2023, this article reviews the current status, challenges and solutions of the research into adenovirus-vectored flavivirus vaccines, so as to provide the reference for the development of relevant vaccines.

8.
Nano Lett ; 22(9): 3737-3743, 2022 May 11.
Artigo em Inglês | MEDLINE | ID: mdl-35451843

RESUMO

A major challenge in topological magnetism lies in the three-dimensional (3D) exploration of their magnetic textures. A recent focus has been the question of how 2D skyrmion sheets vertically stack to form distinct types of 3D topological strings. Being able to manipulate the vertical coupling should therefore provide a route to the engineering of topological states. Here, we present a new type of axially bound magnetic skyrmion string state in which the strings in two distinct materials are glued together across their interface. With quasi-tomographic resonant elastic X-ray scattering, the 3D skyrmion profiles before and after their binding across the interface were unambiguously determined and compared. Their attractive binding is accompanied by repulsive twisting; i.e., the coupled skyrmions mutually affect each other via a compensating twisting. This state exists in chiral magnet-magnetic thin film heterostructures, providing a new arena for the engineering of 3D topological phases.

9.
Nat Commun ; 11(1): 5631, 2020 Nov 06.
Artigo em Inglês | MEDLINE | ID: mdl-33159081

RESUMO

The Berezinskii-Kosterlitz-Thouless (BKT) mechanism, building upon proliferation of topological defects in 2D systems, is the first example of phase transition beyond the Landau-Ginzburg paradigm of symmetry breaking. Such a topological phase transition has long been sought yet undiscovered directly in magnetic materials. Here, we pin down two transitions that bound a BKT phase in an ideal 2D frustrated magnet TmMgGaO4, via nuclear magnetic resonance under in-plane magnetic fields, which do not disturb the low-energy electronic states and allow BKT fluctuations to be detected sensitively. Moreover, by applying out-of-plane fields, we find a critical scaling behavior of the magnetic susceptibility expected for the BKT transition. The experimental findings can be explained by quantum Monte Carlo simulations applied on an accurate triangular-lattice Ising model of the compound which hosts a BKT phase. These results provide a concrete example for the BKT phase and offer an ideal platform for future investigations on the BKT physics in magnetic materials.

12.
J Exp Med ; 217(9)2020 09 07.
Artigo em Inglês | MEDLINE | ID: mdl-32501510

RESUMO

Cross-reactive anti-flaviviral immunity can influence the outcome of infections with heterologous flaviviruses. However, it is unclear how the interplay between cross-reactive antibodies and T cells tilts the balance toward pathogenesis versus protection during secondary Zika virus (ZIKV) and Japanese encephalitis virus (JEV) infections. We show that sera and IgG from JEV-vaccinated humans and JEV-inoculated mice cross-reacted with ZIKV, exacerbated lethal ZIKV infection upon transfer to mice, and promoted viral replication and mortality upon ZIKV infection of the neonates born to immune mothers. In contrast, transfer of CD8+ T cells from JEV-exposed mice was protective, reducing the viral burden and mortality of ZIKV-infected mice and abrogating the lethal effects of antibody-mediated enhancement of ZIKV infection in mice. Conversely, cross-reactive anti-ZIKV antibodies or CD8+ T cells displayed the same pathogenic or protective effects upon JEV infection, with the exception that maternally acquired anti-ZIKV antibodies had no effect on JEV infection of the neonates. These results provide clues for developing safe anti-JEV/ZIKV vaccines.


Assuntos
Anticorpos Antivirais/imunologia , Anticorpos Facilitadores/imunologia , Linfócitos T CD8-Positivos/imunologia , Vírus da Encefalite Japonesa (Espécie)/imunologia , Zika virus/imunologia , Zika virus/patogenicidade , Sequência de Aminoácidos , Animais , Animais Recém-Nascidos , Anticorpos Neutralizantes/imunologia , Linhagem Celular , Criança , Reações Cruzadas/imunologia , Encefalite Japonesa/sangue , Encefalite Japonesa/imunologia , Encefalite Japonesa/virologia , Epitopos/química , Epitopos/imunologia , Humanos , Soros Imunes , Imunoglobulina G/sangue , Imunoglobulina G/imunologia , Lactente , Camundongos Endogâmicos C57BL , Adulto Jovem , Infecção por Zika virus/sangue , Infecção por Zika virus/imunologia , Infecção por Zika virus/virologia
13.
Nat Commun ; 11(1): 2406, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32415071

RESUMO

Charge density wave (CDW) is a startling quantum phenomenon, distorting a metallic lattice into an insulating state with a periodically modulated charge distribution. Astonishingly, such modulations appear in various patterns even within the same family of materials. Moreover, this phenomenon features a puzzling diversity in its dimensional evolution. Here, we propose a general framework, unifying distinct trends of CDW ordering in an isoelectronic group of materials, 2H-MX2 (M = Nb, Ta and X = S, Se). We show that while NbSe2 exhibits a strongly enhanced CDW order in two dimensions, TaSe2 and TaS2 behave oppositely, with CDW being absent in NbS2 entirely. Such a disparity is demonstrated to arise from a competition of ionic charge transfer, electron-phonon coupling, and electron correlation. Despite its simplicity, our approach can, in principle, explain dimensional dependence of CDW in any material, thereby shedding new light on this intriguing quantum phenomenon and its underlying mechanisms.

14.
Cell Rep ; 31(4): 107566, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32348763

RESUMO

The underlying mechanisms by which prior immunity to dengue virus (DENV) affords cross-protection against the related flavivirus Zika virus (ZIKV) are poorly understood. Here, we examine the ability of DENV/ZIKV-cross-reactive CD4+ T cells to protect against versus exacerbate ZIKV infection by using a histocompatibility leukocyte antigen (HLA)-DRB1∗0101 transgenic, interferon α/ß receptor-deficient mouse model that supports robust DENV and ZIKV replication. By mapping the HLA-DRB1∗0101-restricted T cell response, we identify DENV/ZIKV-cross-reactive CD4+ T cell epitopes that stimulate interferon gamma (IFNγ) and/or tumor necrosis factor (TNF) production. Vaccination of naive HLA-DRB1∗0101 transgenic mice with these peptides induces a CD4+ T cell response sufficient to reduce tissue viral burden following ZIKV infection. Notably, this protective response requires IFNγ and/or TNF secretion but not anti-ZIKV immunoglobulin G (IgG) production. Thus, DENV/ZIKV-cross-reactive CD4+ T cells producing canonical Th1 cytokines can suppress ZIKV replication in an antibody-independent manner. These results may have important implications for increasing the efficacy and safety of DENV/ZIKV vaccines and for developing pan-flavivirus vaccines.


Assuntos
Linfócitos T CD4-Positivos/imunologia , Reações Cruzadas/imunologia , Vírus da Dengue/imunologia , Zika virus/imunologia , Animais , Dengue/imunologia , Dengue/virologia , Modelos Animais de Doenças , Humanos , Camundongos , Infecção por Zika virus/imunologia , Infecção por Zika virus/virologia
15.
Virus Res ; 278: 197882, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31981774

RESUMO

Dengue virus (DENV) and Zika virus (ZIKV) are antigenically related mosquito-transmitted viruses which represent a big public health problem. Although the antigenic cross-reactivity between two viruses were intensively investigated at the antibody and T cell levels, how DENV envelope protein domain III (EDIII)-elicited antibodies (Abs) impact the outcome of ZIKV infection is uncertain. Here, our results show that the sera isolated from DENV-EDIII-immunized wild-type mice recognized ZIKV-EDIII and cross-neutralized ZIKV in vitro. Passive transfer of DENV-EDIII-immune sera protected 1-day-old mice against lethal ZIKV challenge. Finally, maternally acquired anti-DENV-EDIII Abs significantly increased the survival of 1-day-old mice born to DENV-EDIII-immunized mothers post ZIKV challenge. These results reveal that DENV-EDIII-induced Abs provide cross-protection against ZIKV and may not mediate the Ab-dependent enhancement of ZIKV infection at the concentration used here. The present study would contribute to the development and application of DENV-EDIII-based vaccines.


Assuntos
Anticorpos Antivirais/imunologia , Proteção Cruzada , Imunização Passiva , Proteínas do Envelope Viral/imunologia , Infecção por Zika virus/prevenção & controle , Animais , Animais Recém-Nascidos/imunologia , Animais Recém-Nascidos/virologia , Anticorpos Neutralizantes/imunologia , Chlorocebus aethiops , Vírus da Dengue/imunologia , Modelos Animais de Doenças , Feminino , Imunidade Materno-Adquirida , Imunização , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Testes de Neutralização , Domínios Proteicos/imunologia , Células Vero , Zika virus/imunologia , Infecção por Zika virus/imunologia
16.
Phys Rev Lett ; 123(20): 206405, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31809103

RESUMO

Metallization of 1T-TaS_{2} is generally initiated at the domain boundary of a charge density wave (CDW), at the expense of its long-range order. However, we demonstrate in this study that the metallization of 1T-TaS_{2} can be also realized without breaking the long-range CDW order upon surface alkali doping. By using scanning tunneling microscopy, we find the long-range CDW order is always persisting, and the metallization is instead associated with additional in-gap excitations. Interestingly, the in-gap excitation is near the top of the lower Hubbard band, in contrast to a conventional electron-doped Mott insulator where it is beneath the upper Hubbard band. In combination with the numerical calculations, we suggest that the appearance of the in-gap excitations near the lower Hubbard band is mainly due to the effectively reduced on-site Coulomb energy by the adsorbed alkali ions.

17.
Phys Rev Lett ; 123(2): 027002, 2019 Jul 12.
Artigo em Inglês | MEDLINE | ID: mdl-31386520

RESUMO

In the electronic nematic state, an electronic system has a lower symmetry than the crystal structure of the same system. Electronic nematic states have been observed in various unconventional superconductors such as cuprate, iron-based, heavy-fermion, and topological superconductors. The relation between nematicity and superconductivity is a major unsolved problem in condensed matter physics. By angle-resolved specific heat measurements, we report bulk quasiparticle evidence of nematicity in the topological superconductor Sr_{x}Bi_{2}Se_{3}. The specific heat exhibited a clear twofold symmetry despite the threefold symmetric lattice. Most importantly, the twofold symmetry appeared in the normal state above the superconducting transition temperature. This is explained by the angle-dependent Zeeman effect due to the anisotropic density of states in the nematic phase. Such results highlight the interrelation between nematicity and unconventional superconductivity.

18.
Nat Commun ; 10(1): 2802, 2019 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-31243284

RESUMO

Superconductivity mediated by phonons is typically conventional, exhibiting a momentum-independent s-wave pairing function, due to the isotropic interactions between electrons and phonons along different crystalline directions. Here, by performing inelastic neutron scattering measurements on a superconducting single crystal of Sr0.1Bi2Se3, a prime candidate for realizing topological superconductivity by doping the topological insulator Bi2Se3, we find that there exist highly anisotropic phonons, with the linewidths of the acoustic phonons increasing substantially at long wavelengths, but only for those along the [001] direction. This observation indicates a large and singular electron-phonon coupling at small momenta, which we propose to give rise to the exotic p-wave nematic superconducting pairing in the MxBi2Se3 (M = Cu, Sr, Nb) superconductor family. Therefore, we show these superconductors to be example systems where electron-phonon interaction can induce more exotic superconducting pairing than the s-wave, consistent with the topological superconductivity.

20.
Nat Commun ; 10(1): 1603, 2019 04 08.
Artigo em Inglês | MEDLINE | ID: mdl-30962440

RESUMO

The superconducting state is formed by the condensation of Cooper pairs and protected by the superconducting gap. The pairing interaction between the two electrons of a Cooper pair determines the gap function. Thus, it is pivotal to detect the gap structure for understanding the mechanism of superconductivity. In cuprate superconductors, it has been well established that the gap may have a d-wave function. This gap function has an alternative sign change in the momentum space. It is however hard to visualize this sign change. Here we report the measurements of scanning tunneling spectroscopy in Bi2Sr2CaCu2O8+δ and conduct the analysis of phase-referenced quasiparticle interference (QPI). We see the seven basic scattering vectors that connect the octet ends of the banana-shaped contour of Fermi surface. The phase-referenced QPI clearly visualizes the sign change of the d-wave gap. Our results illustrate an effective way for determining the sign change of unconventional superconductors.

SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...