Segment 8 encodes a structural protein of infectious salmon anaemia virus (ISAV); the co-linear transcript from Segment 7 probably encodes a non-structural or minor structural protein

Biering, Eirik; Falk, K. George; Hoel, Eirik; Thevarajan, Jegatheswaran; Joerink, Maaike; Nylund, Are; Endresen, Curt; Krossøy, Bjørn

doi:10.3354/dao049117

Cited by 45 publications

(38 citation statements)

References 19 publications

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“…The most conserved proteins between ISAV and influenza virus A/PR/8/34 are PB1 proteins although they share only 31 % amino acid similarity. 59-RACE amplification confirmed the production of a spliced mRNA from segment 7 mRNA ORF1 that encodes the S7 ORF2, as previously published (Bierin et al, 2002; Ritchie et al, 2002) (data not shown). It is to be noted that the ISAV segment 7 ends, previously published by Sandvik et al (2000), were found to be segment 6 ends.…”

supporting

confidence: 58%

“…Segment 8 produces an mRNA transcript containing two overlapping ORF. The smaller ORF1 encodes the matrix protein (M) and the S8 ORF2 was recently shown to be involved in the modulation of type I IFN response together with S7 ORF1 (Bierin et al, 2002;Garcia-Rosado et al, 2008).…”

mentioning

confidence: 99%

“…Similar to influenza viruses, the two smallest ISAV genome segments encode at least two proteins each. Segment 7 produces a collinear transcript mRNA (S7 ORF1) encoding an antagonist of type I interferon (IFN) response, whereas S7 ORF2 protein, identified as a putative nuclear export protein, is encoded by a spliced mRNA (Bierin et al, 2002;Garcia-Rosado et al, 2008;Kibenge et al, 2007;McBeath et al, 2006;Ritchie et al, 2002). Segment 8 produces an mRNA transcript containing two overlapping ORF.…”

mentioning

confidence: 99%

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Completion of the full-length genome sequence of the infectious salmon anemia virus, an aquatic orthomyxovirus-like, and characterization of mAbs

Mérour

LeBerre

Lamoureux

et al. 2010

Journal of General Virology

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We report here the first full-length sequence of the eight ssRNA genome segments of the infectious salmon anemia virus (ISAV, Glesvaer/2/90 isolate), a salmonid orthomyxovirus-like.Comparison of ISAV genome sequence with those of others orthomyxovirus reveals low identity values, and a remarkable feature is the extremely long 59 end UTR of ISAV segments, which all contain an additional conserved motif of unknown function. In addition to the genome nucleotide sequence determination, specific mAbs have been produced through mice immunization with sucrose-purified ISAV. Four mAbs directed against the haemagglutininesterase glycoprotein, the nucleoprotein and free or actin-associated forms of the matrix protein have been characterized by (i) indirect fluorescent antibody test; (ii) virus neutralization; (iii) radioimmunoprecipitation and (iv) Western blot assays. These mAbs will potentially be useful for the development of new diagnostic tests, and the nucleotide sequences will help to establish a reverse genetics system for ISAV.Infectious salmon anemia (ISA) was first observed in Norway from Atlantic salmon (Salmo salar L.) in 1984 (Thorud & Djupvik, 1988). ISA outbreaks have since caused considerable economic losses to the Norwegian salmon farming industry and have also been reported in Scotland (Rowley et al., 1999), in the eastern coast of Canada (Bouchard et al., 1999;Lovely et al., 1999) and has been associated with extensive outbreaks in Chile since June 2007(Godoy et al., 2008. The mortality rate in contaminated salmon farms may vary from 15 to 100 % over several months. Although, ISA virus (ISAV) outbreaks were observed only in Atlantic salmon, the virus was detected from apparently healthy animals in other species (Raynard et al., 2001). The only exception was the isolation of ISAV from diseased Coho salmon (Oncorhynchus kisutch) in Chile in 1999 (Kibenge et al., 2001). Experimental infections showed that other species could be susceptible to ISAV infection, especially juvenile rainbow trout (Oncorhynchus mykiss) for which mortality was recorded after both virus injection and bath immersion, which may represent a threat to the trout industry (Biacchesi et al., 2007).The aetiological agent of ISA was identified as an orthomyxovirus-like with a negative-stranded RNA genome consisting of eight segments (Dannevig et al., 1995;Falk et al., 1997;Mjaaland et al., 1997), and constitutes the only member of the genus Isavirus (Kawaoka et al., 2005). ISAV is an enveloped virus composed of four major structural proteins: the nucleoprotein (66-72 kDa), the matrix protein (22-25 kDa) and two envelope glycoproteins that are the haemagglutinin-esterase glycoprotein (42 kDa) and the fusion protein (47-50 kDa) (Clouthier et al., 2002;Falk et al., 2004). Sequence characterization of ISAV genome segments is almost fully achieved, except for several segment end UTRs (Sandvik et al., 2000). It is now evident that the gene coding assignment to each segment and the putative functions of the ISAV proteins are unique and significa...

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supporting

confidence: 58%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Completion of the full-length genome sequence of the infectious salmon anemia virus, an aquatic orthomyxovirus-like, and characterization of mAbs

Mérour

LeBerre

Lamoureux

et al. 2010

Journal of General Virology

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“…The ISAV genome is composed of eight negative-sense, single-stranded RNA segments, and while nucleotide sequences of all segments have been published (9,43,44,56,66,67,74,75), much remains to be elucidated with respect to protein identification and characterization. A total of 12 proteins have been detected by immunoprecipitation of lysates from radiolabeled infected cells (40), while four major structural proteins have been recognized in purified ISAV particles, including the matrix (M1; 22 to 24 kDa) (7,24), the nucleoprotein (NP; 66 to 71 kDa) (3,24), and two membrane glycoproteins (24). The receptor-binding and receptor-destroying activities are associated with the 42-kDa glycoprotein encoded by segment 6, termed the hemagglutininesterase (HE) (24,25,34,42,43,66), while the activities of the second glycoprotein, glycoprotein 50 (gp50), encoded by segment 5 (9), have not been described previously.…”

Section: Infectious Salmon Anemia Virus (Isav) Is An Enveloped Virusmentioning

confidence: 99%

Characterization of the Infectious Salmon Anemia Virus Fusion Protein

Aspehaug

Mikalsen

Snow

et al. 2005

J Virol

119

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Infectious salmon anemia virus (ISAV) is an orthomyxovirus causing serious disease in Atlantic salmon(Salmo salar L.). This study presents the characterization of the ISAV 50-kDa glycoprotein encoded by segment 5, here termed the viral membrane fusion protein (F). This is the first description of a separate orthomyxovirus F protein, and to our knowledge, the first pH-dependent separate viral F protein described. The ISAV F protein is synthesized as a precursor protein, F 0 , that is proteolytically cleaved to F 1 and F 2 , which are held together by disulfide bridges. The cleaved protein is in a metastable, fusion-activated state that can be triggered by low pH, high temperature, or a high concentration of urea. Cell-cell fusion can be initiated by treatment with trypsin and low pH of ISAV-infected cells and of transfected cells expressing F, although the coexpression of ISAV HE significantly improves fusion. Fusion is initiated at pH 5.4 to 5.6, and the fusion process is coincident with the trimerization of the F protein, or most likely a stabilization of the trimer, suggesting that it represents the formation of the fusogenic structure. Exposure to trypsin and a low pH prior to infection inactivated the virus, demonstrating the nonreversibility of this conformational change. Sequence analyses identified a potential coiled coil and a fusion peptide. Size estimates of F 1 and F 2 and the localization of the putative fusion peptide and theoretical trypsin cleavage sites suggest that the proteolytic cleavage site is after residue K 276 in the protein sequence. Infectious salmon anemia virus (ISAV) is an enveloped virusbelonging to the family Orthomyxoviridae and the genus Isavirus, and it causes serious disease in Atlantic salmon (Salmo salar L.) (51,58,68,71,80). The ISAV genome is composed of eight negative-sense, single-stranded RNA segments, and while nucleotide sequences of all segments have been published (9,43,44,56,66,67,74,75), much remains to be elucidated with respect to protein identification and characterization. A total of 12 proteins have been detected by immunoprecipitation of lysates from radiolabeled infected cells (40), while four major structural proteins have been recognized in purified ISAV particles, including the matrix (M1; 22 to 24 kDa) (7, 24), the nucleoprotein (NP; 66 to 71 kDa) (3, 24), and two membrane glycoproteins (24). The receptor-binding and receptor-destroying activities are associated with the 42-kDa glycoprotein encoded by segment 6, termed the hemagglutininesterase (HE) (24,25,34,42,43,66), while the activities of the second glycoprotein, glycoprotein 50 (gp50), encoded by segment 5 (9), have not been described previously.ISAV pursues a nuclear replication strategy similar to that of the influenza viruses (3, 26) which is initiated by receptor binding and internalization into cellular endosomes, where the viral and cellular membranes fuse in response to low pH (21). The addition of trypsin to the culture medium during ISAV replication has been demonstrated to have a benefici...

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“…Like the influenza A and B viruses, ISAV has a negative-sense RNA genome with eight gene segments that express a total of 10 polypeptides. The smallest segment, segment 8, has two overlapping colinear ORFs that respectively encode two proteins M1 and M2, with M1 being the viral matrix protein with a molecular weight of ∼22 kDa (24). As expected, ISAV M1 is expressed late during infection and accumulates in both nucleus and cytosol (25,26).…”

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confidence: 93%

The crystal structure of an orthomyxovirus matrix protein reveals mechanisms for self-polymerization and membrane association

Tao¹

2017

J Immunol Tech Infect Dis

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Many enveloped viruses encode a matrix protein. In the influenza A virus, the matrix protein M1 polymerizes into a rigid protein layer underneath the viral envelope to help enforce the shape and structural integrity of intact viruses. The influenza virus M1 is also known to mediate virus budding as well as the nuclear export of the viral nucleocapsids and their subsequent packaging into nascent viral particles. Despite extensive studies on the influenza A virus M1 (FLUA-M1), only crystal structures of its N-terminal domain are available. Here we report the crystal structure of the full-length M1 from another orthomyxovirus that infects fish, the infectious salmon anemia virus (ISAV). The structure of ISAV-M1 assumes the shape of an elbow, with its N domain closely resembling that of the FLUA-M1. The C domain, which is connected to the N domain through a flexible linker, is made of four α-helices packed as a tight bundle. In the crystal, ISAV-M1 monomers form infinite 2D arrays with a network of interactions involving both the N and C domains. Results from liposome flotation assays indicated that ISAV-M1 binds membrane via electrostatic interactions that are primarily mediated by a positively charged surface loop from the N domain. Cryoelectron tomography reconstruction of intact ISA virions identified a matrix protein layer adjacent to the inner leaflet of the viral membrane. The physical dimensions of the virion-associated matrix layer are consistent with the 2D ISAV-M1 crystal lattice, suggesting that the crystal lattice is a valid model for studying M1-M1, M1-membrane, and M1-RNP interactions in the virion.ll members of the Orthomyxoviridae family, including the influenza viruses A-D, thogotovirus, and isavirus, encode a matrix protein called M1. In the influenza A virus, M1 is produced by a colinear transcript made from the gene segment 7 (1). As one of the most abundantly made viral proteins, the influenza A virus M1 plays multiple roles during the virus life cycle. Upon viral entry, the acidification of the viral interior in the endosome weakens the interaction between M1 and the viral ribonucleoprotein complexes (vRNPs), thus allowing M1-free vRNPs to be imported to the nucleus for viral RNA replication and transcription (2, 3). As infection proceeds, newly synthesized M1 enters the nucleus to mediate the nuclear export of nascent vRNPs. A "daisy-chain" complex is formed with the vRNP binding to the C-terminal domain of M1 (4) and the N-terminal domain of M1 interacting with the nuclear export protein (NEP), also called NS2. Through its nuclear export signal (NES), NEP is specifically recognized by the cellular exportin Crm1, which then facilitates the transport of vRNPs across the nuclear membrane to the cytoplasm in a RanGTP-dependent manner (5). It has been shown that M1 binding to vRNP in the nucleus is able to block mRNA transcription (4, 6). In the cytosol, M1 interacts with the cytoplasmic tails of the glycoproteins HA and NA. Such interactions promote M1 association with lipid raft membranes and t...

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Segment 8 encodes a structural protein of infectious salmon anaemia virus (ISAV); the co-linear transcript from Segment 7 probably encodes a non-structural or minor structural protein

Cited by 45 publications

References 19 publications

Completion of the full-length genome sequence of the infectious salmon anemia virus, an aquatic orthomyxovirus-like, and characterization of mAbs

Completion of the full-length genome sequence of the infectious salmon anemia virus, an aquatic orthomyxovirus-like, and characterization of mAbs

Characterization of the Infectious Salmon Anemia Virus Fusion Protein

The crystal structure of an orthomyxovirus matrix protein reveals mechanisms for self-polymerization and membrane association

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