27 research outputs found
The DEVD motif of Crimean-Congo hemorrhagic fever virus nucleoprotein is essential for viral replication in tick cells
No full textThe DEVD motif of Crimean-Congo hemorrhagic fever virus nucleoprotein is essential for viral replication in tick cell
Recombinant Rift Valley fever viruses encoding bluetongue virus (BTV) antigens: Immunity and efficacy studies upon a BTV-4 challenge.
No full textBackgroundMany ruminant diseases of viral aetiology can be effectively prevented using appropriate vaccination measures. For diseases such as Rift Valley fever (RVF) the long inter-epizootic periods make routine vaccination programs unfeasible. Coupling RVF prophylaxis with seasonal vaccination programmes by means of multivalent vaccine platforms would help to reduce the risk of new RVF outbreaks.Methodology/principal findingsIn this work we generated recombinant attenuated Rift Valley fever viruses (RVFVs) encoding in place of the virulence factor NSs either the VP2 capsid protein or a truncated form of the non-structural NS1 protein of bluetongue virus serotype 4 (BTV-4). The recombinant viruses were able to carry and express the heterologous BTV genes upon consecutive passages in cell cultures. In murine models, a single immunization was sufficient to protect mice upon RVFV challenge and to elicit a specific immune response against BTV-4 antigens that was fully protective after a BTV-4 boost. In sheep, a natural host for RVFV and BTV, both vaccines proved immunogenic although conferred only partial protection after a virulent BTV-4 reassortant Morocco strain challenge.Conclusions/significanceThough additional optimization will be needed to improve the efficacy data against BTV in sheep, our findings warrant further developments of attenuated RVFV as a dual vaccine platform carrying heterologous immune relevant antigens for ruminant diseases in RVF risk areas
Cloning, expression and electrophysiological characterization of glycine receptor alpha subunit from zebrafish
No full textThe glycine receptor is a ligand-gated anion channel protein, providing inhibitory drive within the nervous system. We report here the isolation and functional characterization of a novel alpha subunit (alpha-Z1) of the glycine receptor from adult zebrafish (Danio rerio) brain. The predicted amino acid sequence is 86%, 81% and 77% identical to mammalian isoforms alpha-1, alpha-3 and alpha-2, respectively. alpha-Z1 exhibits many of the molecular features of mammalian alpha-1, but the sequence patterns in the M4 and C-terminal domains are more similar to alpha-2/alpha-3. Phylogenetic analysis indicates that alpha-Z1 is more closely related to the mammalian alpha-l subunits, being positioned, however, on a distinct branch. The alpha-Z1 messenger RNA is 9.5 kb, similar to that described previously for alpha-1 messenger RNAs. When expressed in Xenopus oocytes or a human cell line (BOSC 23), alpha-Z1 forms a homomeric receptor which is activated by glycine and antagonized by strychnine. This receptor demonstrates unexpectedly high sensitivity to taurine and can also be activated by GABA. These results are consistent with physiological findings in lamprey and goldfish, and they suggest that this teleost fish glycine receptor displays a lower selectivity to neurotransmitters than that reported for glycine mammalian receptors. (C) 1999 IBRO. Published by Elsevier Science Ltd
Crimean–Congo haemorrhagic fever virus uses LDLR to bind and enter host cells
No full textClimate change and population densities accelerated transmission of highly pathogenic viruses to humans, including the Crimean–Congo haemorrhagic fever virus (CCHFV). Here we report that the Low Density Lipoprotein Receptor (LDLR) is a critical receptor for CCHFV cell entry, playing a vital role in CCHFV infection in cell culture and blood vessel organoids. The interaction between CCHFV and LDLR is highly specific, with other members of the LDLR protein family failing to bind to or neutralize the virus. Biosensor experiments demonstrate that LDLR specifically binds the surface glycoproteins of CCHFV. Importantly, mice lacking LDLR exhibit a delay in CCHFV-induced disease. Furthermore, we identified the presence of Apolipoprotein E (ApoE) on CCHFV particles. Our findings highlight the essential role of LDLR in CCHFV infection, irrespective of ApoE presence, when the virus is produced in tick cells. This discovery holds profound implications for the development of future therapies against CCHFV
ISG15 overexpression compensates the defect of Crimean-Congo hemorrhagic fever virus polymerase bearing a protease-inactive ovarian tumor domain.
No full textCrimean-Congo Hemorrhagic Fever virus (CCHFV; family Nairoviridae) is an extremely pathogenic member of the Bunyavirales order. Previous studies have shown that the N-terminal domain of the CCHFV polymerase (L) contains an ovarian tumor-type protease (OTU) domain with the capability to remove both ubiquitin and ISG15 molecules from proteins. The approximately 200 amino acids-long OTU domain, if ectopically expressed, can interfere with both the induction of antiviral type I interferons (IFN) as well as the IFN-stimulated signaling. A OTU protease mutant (C40A), by contrast, was inactive in that respect. However, the effect of the OTU protease activity in the context of the full-length L protein (approximately 4000 amino acids) is only poorly characterized, and recombinant CCHFV with the C40A mutation could not be rescued. Here, we employed transcriptionally active virus-like particles (tc-VLPs) to investigate the interaction between the L-embedded OTU protease and the IFN system. Our data show a cis requirement of the OTU protease for optimal CCHFV polymerase activity in human HuH-7 cells. The L-embedded OTU did not influence IFN signaling, the sensitivity to IFN, or IFN induction. Moreover, the attenuation of OTU C40A-mutated L could not be relieved by inactivating the IFN response, but after overexpression of conjugation-competent ISG15 the polymerase activity recovered to wild-type levels. Consequently, ISG15 was used to produce OTU-deficient tc-VLPs, a potential vaccine candidate. Our data thus indicate that in the context of full-length L the OTU domain is important for the regulation of CCHFV polymerase by ISG15
A Virus-Like Particle System Identifies the Endonuclease Domain of Crimean-Congo Hemorrhagic Fever Virus
No full textIDENTIFICATION OF AN IMPORTANT FACTOR INVOLVED IN CCHFV INFECTION
No full textDespite intensive research, much of the molecular pathogenesis of CCHFV is still unknown. Genome-wide screening methods (particularly CRISPR/Cas9-based screens and insertional mutagenesis in haploid cell systems) have facilitated and accelerated the identification and characterization of host genes involved in infectious diseases. Combining haploid cells with
genome saturating chemical mutagenesis using N-Ethyl-N-nitrosourea, we have developed an unbiased screening system that interrogates single nucleotide variants for their relevance in viral infections. To identify host factors involved in CCHFV infections, we performed resistant screens with a viral RNA replication competent vesicular stomatitis virus, pseudotyped with the glycoproteins of the CCHFV (VSV-CCHF_G). Resistant clones were individually selected, expanded and rescreened using the infectious CCHFV IbAr10200 laboratory strain. Subsequently, whole exome sequencing was conducted on the resistant clones. Three clones showing nearly 100% resistance to CCHFV displayed mutations in the gene encoding for protein we named X. Through the use of knocked out haploid and diploid cells as well as soluble form of this protein on VSV-CCHF_G, CCHFV IbAr 10200 and CCHFV isolate, we showed that this protein is important for CCHFV infection. These data were then confirmed in vivo, in a mice model. By using an unbiaised screening system, our study identified an important factor involved for CCHFV cell entry and infection
Structure of Crimean-Congo Hemorrhagic Fever Virus Nucleoprotein: Superhelical Homo-Oligomers and the Role of Caspase-3 Cleavage
No full textStructure of Crimean-Congo hemorrhagic fever virus nucleoprotein: superhelical homo-oligomers and the role of caspase-3 cleavage
No full textCrimean-Congo hemorrhagic fever, a severe hemorrhagic disease found throughout Africa, Europe, and Asia, is caused by the tick-borne Crimean-Congo hemorrhagic fever virus (CCHFV). CCHFV is a negative-sense single-stranded RNA (ssRNA) virus belonging to the Nairovirus genus of the Bunyaviridae family. Its genome of three single-stranded RNA segments is encapsidated by the nucleocapsid protein (CCHFV N) to form the ribonucleoprotein complex. This ribonucleoprotein complex is required during replication and transcription of the viral genomic RNA. Here, we present the crystal structures of the CCHFV N in two distinct forms, an oligomeric form comprised of double antiparallel superhelices and a monomeric form. The head-to-tail interaction of the stalk region of one CCHFV N subunit with the base of the globular body of the adjacent subunit stabilizes the helical organization of the oligomeric form of CCHFV N. It also masks the conserved caspase-3 cleavage site present at the tip of the stalk region from host cell caspase-3 interaction and cleavage. By incubation with primer-length ssRNAs, we also obtained the crystal structure of CCHFV N in its monomeric form, which is similar to a recently published structure. The conformational change of CCHFV N upon deoligomerization results in the exposure of the caspase-3 cleavage site and subjects CCHFV N to caspase-3 cleavage. Mutations of this cleavage site inhibit cleavage by caspase-3 and result in enhanced viral polymerase activity. Thus, cleavage of CCHFV N by host cell caspase-3 appears to be crucial for controlling viral RNA synthesis and represents an important host defense mechanism against CCHFV infection.link_to_OA_fulltex
Low-density lipoprotein receptor–related protein 1 (LRP1) as an auxiliary host factor for RNA viruses
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