Roles of viroplasm‐like structures formed by nonstructural protein NSs in infection with severe fever with thrombocytopenia syndrome virus

Wu, Xiaodong; Qi, Xian; Liang, Mifang; Li, Chuan; Cardona, Carol J.; Li, Dexin; Xing, Zheng

doi:10.1096/fj.13-243857

Cited by 60 publications

(86 citation statements)

References 49 publications

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“…The nonstructural proteins of YFV, Japanese encephalitis virus, and dengue virus were usually expressed on the surface of and/ or secreted extracellular from infected cells (5,10,17,24), which could induce antiviral immunity. However, SFTSV/ NSs was expressed as cytoplasmic inclusion bodies in infected cells (15,20), which was further verified by locating NSs in SFTSV-infected DH82 cells cultured for 3 days but not secreted to their culture medium by ELISA and cell immunofluorescence test in this study (Supplementary Fig. S1; Supplementary Data are available online at www.liebertpub.com/vim).…”

Section: Discussionsupporting

confidence: 72%

“…It was also thought to be involved in the replication of SFTSV, as it was found to have an interaction with nucleoprotein and RNA in the infected cells (20). It was frustrating, however, that we did not observe the expected effects as pre-exposure vaccination with rSFTSV/NSs did not elicit efficient virus clearance in SFTSV-infected mice.…”

Section: Discussionmentioning

confidence: 72%

“…Color development was performed using A + B TMB color liquid (Wantai BioPharm), and the OD values were measured at 450 nm in an ELISA reader. DH82 cells inoculated on coverslips and cultured for 3 days after being infected with SFTSV were used to perform immunofluorescence assay to check the specificity of recognition of anti-NSs antibodies and NSs in cells according to the protocol described elsewhere (20). Meanwhile, cell culture medium was collected and used to detect the potential NSs secreted out of cells by ELISA; inparallel cell lysate was used to detect the NSs in cells.…”

Section: Figmentioning

confidence: 99%

“…Researchers have recently also found that SFTSV NSs had a similar effect on the viral multiplication, through the regulation of and escape from the host's innate immunity (15,16,20). Based on the physician's experience in clinical practice of SFTS treatment, it is unacceptable to give extrinsic IFN to SFTS patients due to the serious side effects of IFN administration, for example, severe fever, leukocytopenia, and thrombocytopenia, which are just the typical symptoms caused by SFTSV infection.…”

Section: Introductionmentioning

confidence: 99%

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Immunization with Recombinant SFTSV/NSs Protein Does Not Promote Virus Clearance in SFTSV-Infected C57BL/6J Mice

Huang²,

Bai³

et al. 2015

Viral Immunology

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The severe fever with thrombocytopenia syndrome (SFTS), caused by a novel Phlebovirus in the Bunyaviridae family named SFTS virus (SFTSV), is an emerging hemorrhagic fever with a wide distribution and high casefatality rate. Neither effective treatment nor vaccines are available to treat and prevent this disease to date. It was recently reported that SFTSV nonstructural protein in S segment (SFTSV/NSs) functioned as the interferon (IFN) antagonist targeting for suppressing host's innate immunity. This study was designed to investigate the potential of recombinant SFTSV (rSFTSV)/NSs protein for inducing anti-NSs antibodies by pre-exposure vaccination to block SFTSV/NSs in the SFTSV-infected C57BL/6J mice. All mice in the rSFTSV/NSsvaccinated group, negative control group, and blank control group survived with no visible clinical abnormities throughout the experiment, except for their sacrifice for sampling at each observation point. However, unexpectedly, a negative effect on the bodyweight of rSFTSV/NSs-vaccinated mice was observed after 21 days postinoculation. Pre-exposure vaccination with rSFTSV/NSs did not accelerate virus removal in mice though high titer of anti-NSs antibodies and elevated IFN-c were detected in sera. Before virus challenge, the rSFTSV/ NSs-vaccinated mice and negative control mice had a larger amount of platelets (PLT) than the blank control mice, which indicated that Freund's adjuvants could stimulate PLT production. In the aspect of cytokines, the rSFTSV/NSs-vaccinated mice had a 5-to 10-fold increase in interleukin (IL)-2, IL-5, IL-6, IFN-c, and tumor necrosis factor-a, which probably just had a negative effect on the bodyweight of mice. In general, therefore, previous vaccination with rSFTSV/NSs did not accelerate virus clearance in the SFTSV-infected mice.

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Section: Discussionsupporting

confidence: 72%

Section: Discussionmentioning

confidence: 72%

Section: Figmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Immunization with Recombinant SFTSV/NSs Protein Does Not Promote Virus Clearance in SFTSV-Infected C57BL/6J Mice

Huang²,

Bai³

et al. 2015

Viral Immunology

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“…It has been reported previously that the NSs proteins of both Bunyamwera orthobunyavirus (BUNV) and RVFV (37,40) inhibit the viral polymerase as measured by minigenome assays. SFTSV NSs forms distinct punctate structures in the cytoplasm of infected or plasmid-transfected cells (45)(46)(47)(48). The NSs structures have been shown to colocalize with N protein and to be associated with viral RNAs, suggesting that NSs plays a role in the replication of the virus (47).…”

Section: Resultsmentioning

confidence: 99%

Reverse Genetics System for Severe Fever with Thrombocytopenia Syndrome Virus

Brennan

Zhang

et al. 2015

J Virol

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Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging tick-borne pathogen that was first reported in China in 2009. Phylogenetic analysis of the viral genome showed that SFTS virus represents a new lineage within the Phlebovirus genus, distinct from the existing sandfly fever and Uukuniemi virus groups, in the family Bunyaviridae. SFTS disease is characterized by gastrointestinal symptoms, chills, joint pain, myalgia, thrombocytopenia, leukocytopenia, and some hemorrhagic manifestations with a case fatality rate of about 2 to 15%. Here we report the development of reverse genetics systems to study STFSV replication and pathogenesis. We developed and optimized functional T7 polymerase-based M-and S-segment minigenome assays, which revealed errors in the published terminal sequences of the S segment of the Hubei 29 strain of SFTSV. We then generated recombinant viruses from cloned cDNAs prepared to the antigenomic RNAs both of the minimally passaged virus (HB29) and of a cell culture-adapted strain designated HB29pp. The growth properties, pattern of viral protein synthesis, and subcellular localization of viral N and NSs proteins of wild-type HB29pp (wtHB29pp) and recombinant HB29pp viruses were indistinguishable. We also show that the viruses fail to shut off host cell polypeptide production. The robust reverse genetics system described will be a valuable tool for the design of therapeutics and the development of killed and attenuated vaccines against this important emerging pathogen. IMPORTANCESFTSV and related tick-borne phleboviruses such as Heartland virus are emerging viruses shown to cause severe disease in humans in the Far East and the United States, respectively. Study of these novel pathogens would be facilitated by technology to manipulate these viruses in a laboratory setting using reverse genetics. Here, we report the generation of infectious SFTSV from cDNA clones and demonstrate that the behavior of recombinant viruses is similar to that of the wild type. This advance will allow for further dissection of the roles of each of the viral proteins in the context of virus infection, as well as help in the development of antiviral drugs and protective vaccines.T he family Bunyaviridae is one of the largest taxonomic groupings of RNA viruses, containing over 350 named isolates that are classified into five genera: Hantavirus, Nairovirus, Orthobunyavirus, Phlebovirus, and Tospovirus (1). All viruses share a genome structure that comprises three segments of negative-sense or ambisense RNA, named small (S), medium (M), and large (L). The S segment encodes the nucleocapsid (N) protein; the M segment encodes the virion glycoproteins Gn and Gc; and the L segment encodes the L protein, the viral RNA-dependent RNA polymerase. Some viruses also encode nonstructural proteins on the S and M segments. Viruses that impinge on human health, either directly by causing human disease or indirectly by causing economic losses of domestic animals or crop plants, are found in each of the five gener...

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A novel viral RNA helicase with an independent translation enhancement activity

Abraham

Savithri

2016

FEBS Letters

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Edited by Tamas DalmayRNA helicases have not been identified among negative sense RNA viruses. In this study, it is shown that Nonstructural protein (NSs) of Groundnut bud necrosis virus (GBNV) acts as a Mg 2+ -and ATP-dependent bipolar RNA helicase. Biophysical and biochemical analysis of the deletion mutants (ND124 NSs, CD80 NSs) revealed that both the N-and C-terminal residues are required for substrate binding, oligomerization and helicase activity, but are dispensable for ATPase activity. Interestingly, NSs could enhance the translation of RNA (~10-fold) independent of its helicase activity. This is the first report of a RNA helicase from negative strand RNA viruses.

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Roles of viroplasm‐like structures formed by nonstructural protein NSs in infection with severe fever with thrombocytopenia syndrome virus

Cited by 60 publications

References 49 publications

Immunization with Recombinant SFTSV/NSs Protein Does Not Promote Virus Clearance in SFTSV-Infected C57BL/6J Mice

Immunization with Recombinant SFTSV/NSs Protein Does Not Promote Virus Clearance in SFTSV-Infected C57BL/6J Mice

Reverse Genetics System for Severe Fever with Thrombocytopenia Syndrome Virus

A novel viral RNA helicase with an independent translation enhancement activity

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