Electron microscopy of vitrified-hydrated La Crosse virus

Talmon, Yeshayahu; Prasad, B. V. Venkataram; Clerx, John P.M.; Wang, G J; Chiu, Wah; Hewlett, Martinez J.

doi:10.1128/jvi.61.7.2319-2321.1987

Cited by 46 publications

(12 citation statements)

References 14 publications

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“…Previous studies have shown that the gross morphology of bunyaviruses ranges between icosahedral symmetry as a T = 12 lattice in the case of Rift Valley fever virus (RVFV) ( 26 – 28 ) to a highly pleomorphic morphology in the case of Tula hantavirus ( 29 ), with both tubular and spherical particles being observed. The morphology of peribunyaviruses BUNV and La Crosse virus are intermediate to these extremes ( 30 , 31 ), being near spherical, and with some variation in particle diameter. Our observations suggest that HAZV does not possess icosahedral symmetry and instead is pleomorphic.…”

Section: Resultsmentioning

confidence: 99%

Potassium is a trigger for conformational change in the fusion spike of an enveloped RNA virus

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et al. 2018

Journal of Biological Chemistry

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Many enveloped viruses enter cells through the endocytic network, from which they must subsequently escape through fusion of viral and endosomal membranes. This membrane fusion is mediated by virus-encoded spikes that respond to the dynamic endosomal environment, which triggers conformational changes in the spikes that initiate the fusion process. Several fusion triggers have been identified and include pH, membrane composition, and endosome-resident proteins, and these cues dictate when and where viral fusion occurs. We recently reported that infection with an enveloped bunyavirus requires elevated potassium ion concentrations [K+], controlled by cellular K+ channels, that are encountered during viral transit through maturing endosomes. Here we reveal the molecular basis for the K+ requirement of bunyaviruses through the first direct visualization of a member of the Nairoviridae family, namely Hazara virus (HAZV), using cryo-EM. Using cryo-electron tomography, we observed HAZV spike glycoproteins within infectious HAZV particles exposed to both high and low [K+], which showed that exposure to K+ alone results in dramatic changes to the ultrastructural architecture of the virion surface. In low [K+], the spikes adopted a compact conformation arranged in locally ordered arrays, whereas, following exposure to high [K+], the spikes became extended, and spike–membrane interactions were observed. Viruses exposed to high [K+] also displayed enhanced infectivity, thus identifying K+ as a newly defined trigger that helps promote viral infection. Finally, we confirmed that K+ channel blockers are inhibitory to HAZV infection, highlighting the potential of K+ channels as anti-bunyavirus targets.

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Section: Resultsmentioning

confidence: 99%

Potassium is a trigger for conformational change in the fusion spike of an enveloped RNA virus

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et al. 2018

Journal of Biological Chemistry

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“…The RNPs of many bunya-and arenaviruses have been characterised by negative staining electron microscopy in viruses, infected cells and isolated RNPs. A common aspect is their assembly in flexible "pearl necklace" like circular assemblies (Talmon et al, 1987;Young and Howard, 1983), some bunyavirus, as hantavirus could have rigid RNPs, at least at some steps of the infection (Goldsmith et al, 1995). For orthobunya-and phleboviruses, the flexibility is achieved by the NP -NP interactions that, mediated by flexibly hanging C-and N-terminal extensions, can adopt several protein-protein geometries (Reguera et al, 2014).…”

Section: Bunya-and Arenavirus Rna Replication and Gene Transcriptionmentioning

confidence: 99%

Transcription and replication mechanisms of Bunyaviridae and Arenaviridae L proteins

et al. 2017

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Bunyaviridae and Arenaviridae virus families include an important number of highly pathogenic viruses for humans. They are enveloped viruses with negative stranded RNA genomes divided into three (bunyaviruses) or two (arenaviruses) segments. Each genome segment is coated by the viral nucleoproteins (NPs) and the polymerase (L protein) to form a functional ribonucleoprotein (RNP) complex. The viral RNP provides the necessary context on which the L protein carries out the biosynthetic processes of RNA replication and gene transcription. Decades of research have provided a good understanding of the molecular processes underlying RNA synthesis, both RNA replication and gene transcription, for these two families of viruses. In this review we will provide a global view of the common features, as well as differences, of the molecular biology of Bunyaviridae and Arenaviridae. We will also describe structures of protein and protein-RNA complexes so far determined for these viral families, mainly focusing on the L protein, and discuss their implications for understanding the mechanisms of viral RNA replication and gene transcription within the architecture of viral RNPs, also taking into account the cellular context in which these processes occur. Finally, we will discuss the implications of these structural findings for the development of antiviral drugs to treat human diseases caused by members of the Bunyaviridae and Arenaviridae families.

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“…Electron microscopy studies using negative‐stained samples had also revealed specific surface features of bunyavirus particles, characteristic of each genus, some of which appeared compatible with icosahedral symmetry (Martin et al ., 1985). Analysis of vitrified hydrated samples of particles of La Crosse virus, which belongs to the orthobunyavirus genus, have shown spherical virions of different sizes – similar to those of the phleboviruses but displaying longer spikes – which could be compatible with icosahedral symmetry of various triangulations, although the symmetry of the particles was not identified (Talmon et al ., 1987).…”

Section: Introductionmentioning

confidence: 99%

Class II enveloped viruses

Vaney

Rey

2011

Cellular Microbiology

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SummaryA number of viruses transport their genomic material from cell to cell enclosed within a lipid bilayer that is in turn encased within a symmetric protein shell. This review focuses in a group of RNA viruses that have this type of virions. This group includes several of important human pathogenic viruses, such as the hepatitis C virus, dengue virus, chikungunya virus, rubella virus and the bunyaviruses. The best studied are the flaviviruses and the alphaviruses, which have a b-sheet rich class II viral fusion protein used for entry into susceptible cells. We extend here the class II concept to encompass symmetric viruses in which the envelope proteins are derived from a precursor polyprotein containing two transmembrane glycoproteins arranged in tandem. The first glycoprotein acts as chaperone for the folding of the second one, which carries the membrane fusion function. Since the bunyaviruses, included here, are very similar to the class I arenaviruses in other respects, this analysis highlights the patchwork nature of the various viral functional modules acting at different stages of the virus cycle, which appear assembled from genes of different origins.

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Electron microscopy of vitrified-hydrated La Crosse virus

Cited by 46 publications

References 14 publications

Potassium is a trigger for conformational change in the fusion spike of an enveloped RNA virus

Potassium is a trigger for conformational change in the fusion spike of an enveloped RNA virus

Transcription and replication mechanisms of Bunyaviridae and Arenaviridae L proteins

Class II enveloped viruses

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