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1.
Sci Rep ; 11(1): 616, 2021 Jan 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436670

RESUMO

Riemerella anatipestifer is a major pathogenic microorganism in poultry causing serositis with significant mortality. Serotype 1 and 2 were most pathogenic, prevalent, and liable over the world. In this study, the intracellular metabolites in R. anatipestifer strains RA-CH-1 (serotype 1) and RA-CH-2 (serotype 2) were identified by gas chromatography-mass spectrometer (GC-MS). The metabolic profiles were performed using hierarchical clustering and partial least squares discriminant analysis (PLS-DA). The results of hierarchical cluster analysis showed that the amounts of the detected metabolites were more abundant in RA-CH-2. RA-CH-1 and RA-CH-2 were separated by the PLS-DA model. 24 potential biomarkers participated in nine metabolisms were contributed predominantly to the separation. Based on the complete genome sequence database and metabolite data, the first large-scale metabolic models of iJL463 (RA-CH-1) and iDZ470 (RA-CH-2) were reconstructed. In addition, we explained the change of purine metabolism combined with the transcriptome and metabolomics data. The study showed that it is possible to detect and differentiate between these two organisms based on their intracellular metabolites using GC-MS. The present research fills a gap in the metabolomics characteristics of R. anatipestifer.

3.
Poult Sci ; 100(1): 26-38, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33357689

RESUMO

Duck enteritis virus (DEV) multifunctional tegument protein UL13 is predicted to be a conserved herpesvirus protein kinase; however, little is known about its subcellular localization signal. In this study, through transfection of 2 predicted nuclear signals of DEV UL13 fused to enhanced green fluorescent protein, 2 bipartite nuclear localization signals (NLS) were identified. We found that ivermectin blocked the NLS-mediated nuclear import of DEV UL13, showing that the nuclear localization signal of DEV UL13 is a classical importin α- and ß-dependent process. We constructed a DEV UL13 mutant strain in which the NLS of DEV UL13 was deleted to explore whether deletion of the NLS affects viral replication. Amino acids 4 to 7 and 90 to 96 were predicted to be NLSs, further proving that nuclear import occurs via a classical importin α- and ß-dependent process. We also found that the NLS of pUL13 had no effect on DEV replication in cell culture. Our study enhances the understanding of DEV pUL13. Taken together, these results provide significant information regarding the biological function of pUL13 during DEV infection.

4.
Vaccine ; 39(3): 588-595, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33341307

RESUMO

Salmonella enterica serovar Typhimurium is a major food-borne pathogen that can cause self-limited gastroenteritis or life-threatening invasive diseases in humans. There is no licensed S. Typhimurium vaccine for humans to date. In this study, we attempted to construct a live attenuated vaccine strain of S. Typhimurium based on three genes, namely, the two global regulator genes fnr and arcA and the flagellin subunit gene fliC. The S. Typhimurium three-gene mutant, named SLT39 (ΔfnrΔarcAΔfliC), exhibited a high level of attenuation with a colonization defect in mouse tissues and approximately 104-fold decreased virulence compared with that of the wild-type strain. To evaluate the immunogenicity and protection efficacy of STL39, mice were inoculated twice with a dose of 107 CFU or 108 CFU at a 28-day interval, and the immunized mice were challenged with a lethal dose of the wild-type S. Typhimurium strain one month post second immunization. Compared with mock immunization, SLT39 immunization with either dose elicited significant serum total IgG, IgG1 and IgG2a and faecal IgA responses against inactivated S. Typhimurium antigens at a comparable level post second immunization, whereas the 108 CFU group induced higher levels of duodenal and caecal IgA than the 107 CFU group. Furthermore, the bacterial loads in mouse tissues, including Peyer's patches, spleen and liver, significantly decreased in the two SLT39 immunization groups compared to those in the control group post challenge. Additionally, all mice in the SLT39 (108 CFU) group and 80% of the mice in the SLT39 (107 CFU) group survived the lethal challenge, suggesting full protection and 80% protection efficacy, respectively. Thus, the S. Typhimurium fnr, arcA and fliC mutant proved to be a potential attenuated live vaccine candidate for prevention of homologous infection.

5.
Transbound Emerg Dis ; 2020 Dec 27.
Artigo em Inglês | MEDLINE | ID: mdl-33369177

RESUMO

Duck hepatitis A virus 1 (DHAV-1) is a highly prevalent pathogen within adult ducks causing acute as well as chronic hepatitis which closely emulates the progression of human hepatitis. However, the underlying mechanisms of DHAV-1 persistence and the pathogenesis of chronic liver disease are not well defined. The association between hematopoietic reservoirs of virus and persistent infection is increasingly concerning. Here, we explored the ability of lymphoid replication of DHAV-1 and the effect on immunity. We found that DHAV-1 was able to infect and replicate productively in the lymphoid organs of model ducks, persisting over 6 months. Moreover, a significant correlation of viral loads between these organs and blood was found, documenting a major contribution of lymphoid replication to DHAV-1 viraemia. Along with viral replication, the mRNA of PRRs and immune-related cytokines was up-regulated in these organs during the early phase of infection, showing tissue-dependent expression patterns but all inclining towards Th2 responses due to the consistently higher level of IL-4 than IL-2 and IFN-γ. Additionally, the expression of CCL19, CCL21, MHC-I and MHC-II, which are involved in T cell homing to the periphery and priming, was dysmodulated. Our data indicate that DHAV-1 possesses lymphoid tissue tropism, contributing to persistent infection and chronic hepatitis via altering the early endogenous transcription of immune-related genes and thereby perturbing organic immunity. These results may be useful to develop novel strategies to treat chronic viral hepatitis based on stimulation of the early innate system and regulation of T-cell trafficking.

6.
Sci Total Environ ; : 143142, 2020 Oct 16.
Artigo em Inglês | MEDLINE | ID: mdl-33168253

RESUMO

Modifying the surface of an anode can improve electroactive bacteria (EAB) enrichment, thereby enhancing the performance of the associated microbial electrochemical systems (MESs). In this study, biosynthetic FeS nanoparticles were used to modify the anode in MESs. The experimental results demonstrated that the stable maximum voltage of the FeS composited biochar (FeS/BC)-modified anode reached 0.72 V, which is 20% higher than that of the control. The maximum power density with the FeS/BC anode was 793 mW/m2, which is 46.31% higher than that obtained with the control (542 mW/m2). According to cyclic voltammetry (CV) analysis, FeS/BC facilitates the direct electron transfer between bacteria and the electrode. The biomass protein concentration of the FeS/BC anode was 841.75 µg/cm2, which is almost 1.5 times higher than that of the carbon cloth anode (344.25 µg/cm2); hence, FeS/BC modification can promote biofilm formation. The composition of Geobacter species on the FeS/BC anode (75.16%) was much higher than that on the carbon cloth anode (4.81%). All the results demonstrated that the use of the biosynthetic FeS/BC anode is an environmentally friendly and efficient strategy for enhancing the electroactive biofilm formation and EAB enrichment in MESs.

7.
Vet Res ; 51(1): 135, 2020 Nov 11.
Artigo em Inglês | MEDLINE | ID: mdl-33176874

RESUMO

Duck enteritis virus (DEV) is a member of the Alphaherpesvirinae subfamily. The characteristics of some DEV genes have been reported. However, information regarding the DEV UL47 gene is limited. In this study, we identified the DEV UL47 gene encoding a late structural protein located in the nucleus of infected cells. We further found that two domains of DEV pUL47, amino acids (aa) 40 to 50 and 768 to 777, could function as nuclear localization sequence (NLS) to guide the nuclear localization of pUL47 and nuclear translocation of heterologous proteins, including enhanced green fluorescent protein (EGFP) and beta-galactosidase (ß-Gal). Moreover, pUL47 significantly inhibited polyriboinosinic:polyribocytidylic acid [poly(I:C)]-induced interferon beta (IFN-ß) production and downregulated interferon-stimulated gene (ISG) expression, such as Mx and oligoadenylate synthetase-like (OASL), by interacting with signal transducer and activator of transcription-1 (STAT1).

8.
Poult Sci ; 99(12): 6647-6652, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33248580

RESUMO

To determine the role of glycoprotein I (gI) in duck plague virus (DPV), a gI-deleted mutant (BAC-CHv-ΔgI) and a gI-revertant virus (BAC-CHv-ΔgI Rev) were constructed by using a markerless two-step Red recombination system implemented on the DPV genome cloned into a bacterial artificial chromosome (BAC). Mutants were characterized on duck embryo fibroblast (DEF) cells compared with wild-type virus. BAC-CHv-ΔgI produced viral plaques on DEF cells that were on average approximately 57.2% smaller than those produced by BAC-CHv-ΔgI Rev and wild-type virus. Electron microscopy confirmed that deleting of gI resulted in nucleocapsids accumulated around the cytoplasm vesicles and few of them could complete the final envelopment process. These results clearly indicated that DPV gI plays significant roles in viral cell-cell spread and viral final envelopment process.

9.
Front Immunol ; 11: 558341, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33072096

RESUMO

The host immune system has multiple innate immune receptors that can identify, distinguish and react to viral infections. In innate immune response, the host recognizes pathogen-associated molecular patterns (PAMP) in nucleic acids or viral proteins through pathogen recognition receptors (PRRs), especially toll-like receptors (TLRs) and induces immune cells or infected cells to produce type I Interferons (IFN-I) and pro-inflammatory cytokines, thus when the virus invades the host, innate immunity is the earliest immune mechanism. Besides, cytokine-mediated cell communication is necessary for the proper regulation of immune responses. Therefore, the appropriate activation of innate immunity is necessary for the normal life activities of cells. The suppressor of the cytokine signaling proteins (SOCS) family is one of the main regulators of the innate immune response induced by microbial pathogens. They mainly participate in the negative feedback regulation of cytokine signal transduction through Janus kinase signal transducer and transcriptional activator (JAK/STAT) and other signal pathways. Taken together, this paper reviews the SOCS proteins structures and the function of each domain, as well as the latest knowledge of the role of SOCS proteins in innate immune caused by viral infections and the mechanisms by which SOCS proteins assist viruses to escape host innate immunity. Finally, we discuss potential values of these proteins in future targeted therapies.

10.
Front Microbiol ; 11: 1910, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33013729

RESUMO

The protein encoded by the UL48 gene of alphaherpesviruses is named VP16 or alpha-gene-transactivating factor (α-TIF). In the early stage of viral replication, VP16 is an important transactivator that can activate the transcription of viral immediate-early genes, and in the late stage of viral replication, VP16, as a tegument, is involved in viral assembly. This review will explain the mechanism of VP16 acting as α-TIF to activate the transcription of viral immediate-early genes, its role in the transition from viral latency to reactivation, and its effects on viral assembly and maturation. In addition, this review also provides new insights for further research on the life cycle of alphaherpesviruses and the role of VP16 in the viral life cycle.

11.
Front Microbiol ; 11: 1817, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32973693

RESUMO

Enteroviral replication reorganizes the cellular membrane. Upon infection, viral proteins and hijacked host factors generate unique structures called replication organelles (ROs) to replicate their viral genomes. ROs promote efficient viral genome replication, coordinate the steps of the viral replication cycle, and protect viral RNA from host immune responses. More recent researches have focused on the ultrastructure structures, formation mechanism, and functions in the virus life cycle of ROs. Dynamic model of enterovirus ROs structure is proposed, and the secretory pathway, the autophagy pathway, and lipid metabolism are found to be associated in the formation of ROs. With deeper understanding of ROs, some compounds have been found to show inhibitory effects on viral replication by targeting key proteins in the process of ROs formation. Here, we review the recent findings concerning the role, morphology, biogenesis, formation mechanism, and inhibitors of enterovirus ROs.

12.
Artigo em Inglês | MEDLINE | ID: mdl-32974223

RESUMO

The 3' untranslated region (3' UTR) of positive-sense single-stranded RNA [ssRNA(+)] viruses is highly structured. Multiple elements in the region interact with other nucleotides and proteins of viral and cellular origin to regulate various aspects of the virus life cycle such as replication, translation, and the host-cell response. This review attempts to summarize the primary and higher order structures identified in the 3'UTR of ssRNA(+) viruses and their functional roles.

13.
Aging (Albany NY) ; 12(17): 17503-17527, 2020 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-32897243

RESUMO

Duck Tembusu virus (DTMUV) is an emerging pathogenic flavivirus that has caused enormous economic losses in Southeast Asia. However, the pathogenic mechanism and host's responses after DTMUV infection remain poorly understood. During this study, total mRNA sequencing (RNA-Seq) analysis was used to detect the global gene expression in DEFs at various time points after DTMUV infection. We identified 326 genes altered significantly at all time points, and these genes were dynamically enriched in multifarious biological processes, including apoptosis, innate immune response, DNA replication, cell cycle arrest and DNA repair. Next, the results showed that apoptosis was induced and the proportion of apoptosis increased with time, and pro-apoptotic molecules caspases were activated. The RNA-seq data analysis further revealed that most pro-apoptosis and anti-apoptosis genes were early continually responsive, and the genes involved in both intrinsic and extrinsic apoptotic pathways were initiated. Further, the considerably enriched immune-relevant pathways were involved in apoptosis process, and protein-protein interactions (PPIs) analysis showed that IL6, STAT1, TNFAIP3, CFLAR and PTGS2 may be key regulators of DEFs apoptosis. In conclusion, this study not only contributes to understanding the underlying mechanism of DEFs infection with DTMUV, but also provides new insights into targets screening for antiviral therapy.

14.
Front Microbiol ; 11: 1908, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32849477

RESUMO

Alphaherpesviruses are zoonotic pathogens that can cause a variety of diseases in humans and animals and severely damage health. Alphaherpesvirus infection is a slow and orderly process that can lie dormant for the lifetime of the host but may be reactivated when the immune system is compromised. All alphaherpesviruses feature a protein layer called the tegument that lies between the capsid and the envelope. Virus protein (VP) 22 is one of the most highly expressed tegument proteins; there are more than 2,000 copies of this protein in each viral particle. VP22 can interact with viral proteins, cellular proteins, and chromatin, and these interactions play important roles. This review summarizes the latest literature and discusses the roles of VP22 in viral gene transcription, protein synthesis, virion assembly, and viral cell-to-cell spread with the purpose of enhancing understanding of the life cycle of herpesviruses and other pathogens in host cells. The molecular interaction information herein provides important reference data.

15.
J Virol ; 94(20)2020 09 29.
Artigo em Inglês | MEDLINE | ID: mdl-32759314

RESUMO

Members of the Pegivirus genus, family Flaviviridae, widely infect humans and other mammals, including nonhuman primates, bats, horses, pigs, and rodents, but are not associated with disease. Here, we report a new, genetically distinct pegivirus in goose (Anser cygnoides), the first identified in a nonmammalian host species. Goose pegivirus (GPgV) can be propagated in goslings, embryonated goose eggs, and primary goose embryo fibroblasts, and is thus the first pegivirus that can be efficiently cultured in vitro Experimental infection of GPgV in goslings via intravenous injection revealed robust replication and high lymphotropism. Analysis of the tissue tropism of GPgV revealed that the spleen and thymus were the organs bearing the highest viral loads. Importantly, GPgV could promote clinical manifestations of goose parvovirus infection, including reduced weight gain and 7% mortality. This finding contrasts with the lack of pathogenicity that is characteristic of previously reported pegiviruses.IMPORTANCE Members of the Pegivirus genus, family Flaviviridae, widely infect humans and other mammals, but are described as causing persistent infection and lacking pathogenicity. The efficiency of in vitro replication systems for pegivirus is poor, thus limiting investigation into viral replication steps. Because of that, the pathogenesis, cellular tropism, route of transmission, biology, and epidemiology of pegiviruses remain largely uncovered. Here, we report a phylogenetically distinct goose pegivirus (GPgV) that should be classified as a new species. GPgV proliferated in cell culture in a species- and cell-type-specific manner. Animal experiments show GPgV lymphotropism and promote goose parvovirus clinical manifestations. This study provides the first cell culture model for pegivirus, opening new possibilities for studies of pegivirus molecular biology. More importantly, our findings stand in contrast to the lack of identified pathogenicity of previously reported pegiviruses, which sheds lights on the pathobiology of pegivirus.

16.
Vet Microbiol ; 247: 108730, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32768200

RESUMO

Excessive iron in the bacterial cytoplasm can potentiate the production of harmful reactive oxygen species (ROS). Riemerella anatipestifer (R. anatipestifer, RA), a gram-negative bacterium, encodes an iron uptake system, but its iron detoxification mechanism is unknown. Here, the dps gene of R. anatipestifer CH-1 (RA-CH-1) was deleted using sacB as a counterselection marker. The dps mutant was more sensitive to H2O2 than the wild type in iron-rich conditions but not in iron-limited conditions, suggesting that Dps prevents H2O2-induced damage through iron binding. However, the dps mutant and wild type were identically sensitive to bactericidal antibiotics, and antibiotic treatment did not enhance RA-CH-1 ROS production. Furthermore, Dps prevents DNA damage by binding DNA. The RA-CH-1 dps transcript level was higher in the stationary phase than in the early and exponential phases and was increased by OxyR in the presence of H2O2. Finally, duckling colonization by the dps mutant was similar to that by the wild type at 48 h postinfection but significantly lower at 60 h postinfection, suggesting that RA-CH-1 Dps is not involved in host invasion but increases resistance to host clearance. Dps thus likely plays an important role in R. anatipestifer physiology and pathogenesis through protecting against oxidative stress.

17.
Sci Rep ; 10(1): 12423, 2020 07 24.
Artigo em Inglês | MEDLINE | ID: mdl-32709930

RESUMO

Duck Tembusu virus (DTMUV), a mosquito-borne Flavivirus, has caused serious economic losses for the Chinese poultry industry. The genome is translated into a polyprotein that is cleaved to mature protein by host and viral proteases in the host cell, and this proteolytic process is important for the viral life cycle. However, the cleavage mechanism of DTMUV polyprotein is still unclear. In this study, we identified that several amino acids (P1-R, P1'-G, P2-R, P3-T, and P4-V) were vital for NS2A/2B cleavage. Meanwhile, both NS2A and NS2B were essential in cis for polyprotein NS2A/2B intramolecular cleavage. Subsequently, a DTMUV replicon and an infectious clone showed that the P1 site is essential to viral replication, while a mutation in P1' could boost viral RNA replication. Furthermore, a recombinant virus with P1 and P1' site mutations named rDTMUV-NS2A/2B-P1P1'(AA) was rescued from transfected BHK21 cells. The maximum viral titers and viral genome copies of rDTMUV-NS2A/2B-P1P1'(AA) were much lower than those of rDTMUV-WT both in the intracellular and extracellular samples of transfected and infected BHK21 cells. Taken together, the NS2A/2B cleavage sites processed by the NS2B3 protease are vital for DTMUV proliferation and virulence.

18.
Virol J ; 17(1): 112, 2020 07 23.
Artigo em Inglês | MEDLINE | ID: mdl-32703221

RESUMO

BACKGROUND: eIF2α is a regulatory node that controls protein synthesis initiation by its phosphorylation or dephosphorylation. General control nonderepressible-2 (GCN2), protein kinase R-like endoplasmic reticulum kinase (PERK), double-stranded RNA (dsRNA)-dependent protein kinase (PKR) and heme-regulated inhibitor (HRI) are four kinases that regulate eIF2α phosphorylation. MAIN BODY: In the viral infection process, dsRNA or viral proteins produced by viral proliferation activate different eIF2α kinases, resulting in eIF2α phosphorylation, which hinders ternary tRNAMet-GTP-eIF2 complex formation and inhibits host or viral protein synthesis. The stalled messenger ribonucleoprotein (mRNP) complex aggregates under viral infection stress to form stress granules (SGs), which encapsulate viral RNA and transcription- and translation-related proteins, thereby limiting virus proliferation. However, many viruses have evolved a corresponding escape mechanism to synthesize their own proteins in the event of host protein synthesis shutdown and SG formation caused by eIF2α phosphorylation, and viruses can block the cell replication cycle through the PERK-eIF2α pathway, providing a favorable environment for their own replication. Subsequently, viruses can induce host cell autophagy or apoptosis through the eIF2α-ATF4-CHOP pathway. CONCLUSIONS: This review summarizes the role of eIF2α in viral infection to provide a reference for studying the interactions between viruses and hosts.

19.
Inorg Chem ; 59(15): 11020-11027, 2020 Aug 03.
Artigo em Inglês | MEDLINE | ID: mdl-32674571

RESUMO

For endohedral metallofullerenes (EMFs), it has been well established that the cage shape and size should match those of the endohedral cluster. As a result, sufficient cluster-cage interaction can be achieved, which is essential for mutual stabilization. Nevertheless, how a small endohedral cluster nests in a giant fullerene has been less explored. Herein, we report a pair of large oxide-cluster fullerene (OCF) isomers, denoted as Ho2O@C92-I and -II. Crystallographic studies reveal that major isomer-I possesses a D3(85)-C92 cage with a highly stretched Ho2O cluster inside, which contributes to achieving regular metal-cage contacts. Density functional theory (DFT) computations also reveal the predominant abundance of the D3(85) isomer relative to the other two possible minor species including C1(67) and C2(64) isomers. Moreover, electrochemical (EC) studies verify that the isomers exhibit almost identical redox behaviors, indicating their similar cage structures. On the basis of the remarkable topological similarity of D3(85) and C1(67) isomers, isomer-II is likely to be Ho2O@C1(67)-C92, though it remains to be confirmed. Our studies thus provide new insights into the cage-cluster interplay and cage isomerization, both contributing to a better understanding of large EMFs.

20.
J Virol ; 94(16)2020 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-32522848

RESUMO

Duck Tembusu virus (DTMUV) (genus Flavivirus) is a causative agent of duck egg drop syndrome and has zoonotic potential. The positive-strand RNA genomes of flaviviruses are commonly translated in a cap-dependent manner. However, dengue and Zika viruses also exhibit cap-independent translation. In this study, we show that RNAs containing 5' and 3' untranslated regions (UTRs) of DTMUV, mosquito-borne Tembusu virus (TMUV), and Japanese encephalitis virus can be translated in a cap-independent manner in mammalian, avian, and mosquito cells. The ability of the 5' UTRs of flaviviruses to direct the translation of a second open reading frame in bicistronic RNAs was much less than that observed for internal ribosome entry site (IRES) encephalomyocarditis virus, indicating a lack of substantial IRES activity. Instead, cap-independent translation of DTMUV RNA was dependent on the presence of a 3' UTR, RNA secondary structures located in both UTRs, and specific RNA sequences. Mutations inhibiting cap-independent translation decreased DTMUV proliferation in vitro and delayed, but did not prevent, the death of infected duck embryos. Thus, the 5' and 3' UTRs of DTMUV enable the virus to use a cap- and IRES-independent RNA genome translation strategy that is important for its propagation and virulence.IMPORTANCE The genus Flavivirus includes major human pathogens, as well as animal-infecting viruses with zoonotic potential. In order to counteract the threats these viruses represent, it is important to understand their basic biology to develop universal attenuation strategies. Here, we demonstrate that five different flaviviruses use cap-independent translation, indicating that the phenomenon is probably common to all members of the genus. The mechanism used for flavivirus cap-independent translation was found to be different from that of IRES-mediated translation and dependent on both 5' and 3' UTRs that act in cis As cap-independent translation was also observed in mosquito cells, its role in flavivirus infection is unlikely to be limited to the evasion of consequences of the shutoff of host translation. We found that the inhibition of cap-independent translation results in decreased viral proliferation, indicating that the strategy could be applied to produce attenuated variants of flaviviruses as potential vaccine candidates.

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