scholarly journals A ΩXaV motif in the Rift Valley fever virus NSs protein is essential for degrading p62, forming nuclear filaments and virulence

2015 ◽  
Vol 112 (19) ◽  
pp. 6021-6026 ◽  
Author(s):  
Normand Cyr ◽  
Cynthia de la Fuente ◽  
Lauriane Lecoq ◽  
Irene Guendel ◽  
Philippe R. Chabot ◽  
...  
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Excision Repair ◽  
Rna Virus ◽  
Nonstructural Protein ◽  
Rift Valley Fever Virus ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
Valley Fever ◽  
Infected Cells

Rift Valley fever virus (RVFV) is a single-stranded RNA virus capable of inducing fatal hemorrhagic fever in humans. A key component of RVFV virulence is its ability to form nuclear filaments through interactions between the viral nonstructural protein NSs and the host general transcription factor TFIIH. Here, we identify an interaction between a ΩXaV motif in NSs and the p62 subunit of TFIIH. This motif in NSs is similar to ΩXaV motifs found in nucleotide excision repair (NER) factors and transcription factors known to interact with p62. Structural and biophysical studies demonstrate that NSs binds to p62 in a similar manner as these other factors. Functional studies in RVFV-infected cells show that the ΩXaV motif is required for both nuclear filament formation and degradation of p62. Consistent with the fact that the RVFV can be distinguished from otherBunyaviridae-family viruses due to its ability to form nuclear filaments in infected cells, the motif is absent in the NSs proteins of otherBunyaviridae-family viruses. Taken together, our studies demonstrate that p62 binding to NSs through the ΩXaV motif is essential for degrading p62, forming nuclear filaments and enhancing RVFV virulence. In addition, these results show how the RVFV incorporates a simple motif into the NSs protein that enables it to functionally mimic host cell proteins that bind the p62 subunit of TFIIH.

scholarly journals The S Segment of Rift Valley Fever Phlebovirus (Bunyaviridae) Carries Determinants for Attenuation and Virulence in Mice

2000 ◽  
Vol 74 (3) ◽  
pp. 1538-1543 ◽  
Author(s):  
P. Vialat ◽  
A. Billecocq ◽  
A. Kohl ◽  
M. Bouloy
Keyword(s):  
Rift Valley ◽  
Rift Valley Fever ◽  
Nonstructural Protein ◽  
Rift Valley Fever Virus ◽  
Virulent Strain ◽  
Coding Region ◽  
Valley Fever ◽  
Attenuated Virus ◽  
Infected Cells

ABSTRACT Unlike all the other Rift Valley fever virus strains (Bunyaviridae, Phlebovirus) studied so far, clone 13, a naturally attenuated virus, does not form the filaments composed of the NSs nonstructural protein in the nuclei of infected cells (R. Muller, J. F. Saluzzo, N. Lopez, T. Drier, M. Turell, J. Smith, and M. Bouloy, Am. J. Trop. Med. Hyg. 53:405–411, 1995). This defect is correlated with a large in-frame deletion in the NSs coding region of the S segment of the tripartite genome. Here, we show that the truncated NSs protein of clone 13 is expressed and remains in the cytoplasm, where it is degraded rapidly by the proteasome. Through the analysis of reassortants between clone 13 and a virulent strain, we localized the marker(s) of attenuation in the S segment of this attenuated virus. This result raises questions regarding the role of NSs in pathogenesis and highlights, for the first time in theBunyaviridae family, a major role of the S segment in virulence and attenuation, possibly associated with a defect in the nonstructural protein.

scholarly journals Virion-associated spermidine transmits with Rift Valley fever virus particles to maintain infectivity

2020 ◽  
Author(s):  
Vincent Mastrodomenico ◽  
Jeremy J. Esin ◽  
Shefah Qazi ◽  
Oreoluwa S. Omoba ◽  
Brittany L. Fung ◽  
...  
Keyword(s):  
Virus Replication ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rna Virus ◽  
Rift Valley Fever Virus ◽  
Acid Synthesis ◽  
Fever Virus ◽  
Virus Infectivity ◽  
Cellular Functions ◽  
Valley Fever

AbstractViruses require host cell metabolites to productively infect, and the mechanisms by which viruses usurp these molecules is diverse. One group of cellular metabolites important in virus infection is the polyamines, small positively-charged molecules involved in cell cycle, translation, and nucleic acid synthesis, among other cellular functions. Polyamines also support replication of diverse viruses, and they are important for processes such as transcription, translation, and viral protein enzymatic activity. Rift Valley fever virus (RVFV) is a negative-sense RNA virus that requires polyamines to produce infectious particles. In polyamine depleted conditions, noninfectious particles are produced that interfere with virus replication and stimulate immune signaling. Here, we find that RVFV relies on virion-associated polyamines to maintain infectivity. We show that RVFV replication is facilitated by any of the three biogenic polyamines; however, we specifically find spermidine associated with purified virions. Using a panel of polyamine homologs, we observe that virions can also associate with (R)-3-methylspermidine and norspermidine, though not with other less homologous molecules. Using polyamine reporter cells, we demonstrate that virion-associated polyamines transmit from one infected cell to another. Finally, we find that virions devoid of polyamines are unstable and cannot be supplemented with exogenous polyamines to regain stability or infectivity. These data highlight a unique role for polyamines, and spermidine in particular, in maintaining virus infectivity, a function not previously appreciated. Further, these studies are the first to identify polyamines associated with RVFV virions. Targeting polyamines represents a promising antiviral strategy, and this work highlights a new mechanism by which we can inhibit virus replication through FDA-approved polyamine depleting pharmaceuticals.

scholarly journals Evaluation of the Efficacy, Potential for Vector Transmission, and Duration of Immunity of MP-12, an Attenuated Rift Valley Fever Virus Vaccine Candidate, in Sheep

2015 ◽  
Vol 22 (8) ◽  
pp. 930-937 ◽  
Author(s):  
Myrna M. Miller ◽  
Kristine E. Bennett ◽  
Barbara S. Drolet ◽  
Robbin Lindsay ◽  
James O. Mecham ◽  
...  
Keyword(s):  
Rift Valley ◽  
Neutralizing Antibodies ◽  
Rift Valley Fever ◽  
Nonstructural Protein ◽  
Rift Valley Fever Virus ◽  
Clinical Signs ◽  
Fever Virus ◽  
Vector Transmission ◽  
Valley Fever ◽  
Virulent Challenge

ABSTRACTRift Valley fever virus (RVFV) causes serious disease in ruminants and humans in Africa. In North America, there are susceptible ruminant hosts and competent mosquito vectors, yet there are no fully licensed animal vaccines for this arthropod-borne virus, should it be introduced. Studies in sheep and cattle have found the attenuated strain of RVFV, MP-12, to be both safe and efficacious based on early testing, and a 2-year conditional license for use in U.S. livestock has been issued. The purpose of this study was to further determine the vaccine's potential to infect mosquitoes, the duration of humoral immunity to 24 months postvaccination, and the ability to prevent disease and viremia from a virulent challenge. Vaccination experiments conducted in sheep found no evidence of a potential for vector transmission to 4 North American mosquito species. Neutralizing antibodies were elicited, with titers of >1:40 still present at 24 months postvaccination. Vaccinates were protected from clinical signs and detectable viremia after challenge with virulent virus, while control sheep had fever and high-titered viremia extending for 5 days. Antibodies to three viral proteins (nucleocapsid N, the N-terminal half of glycoprotein GN, and the nonstructural protein from the short segment NSs) were also detected to 24 months using competitive enzyme-linked immunosorbent assays. This study demonstrates that the MP-12 vaccine given as a single dose in sheep generates protective immunity to a virulent challenge with antibody duration of at least 2 years, with no evidence of a risk for vector transmission.

scholarly journals A Haploid Genetic Screen Identifies Heparan Sulfate Proteoglycans Supporting Rift Valley Fever Virus Infection

2015 ◽  
Vol 90 (3) ◽  
pp. 1414-1423 ◽  
Author(s):  
Amber M. Riblett ◽  
Vincent A. Blomen ◽  
Lucas T. Jae ◽  
Louis A. Altamura ◽  
Robert W. Doms ◽  
...  
Keyword(s):  
Heparan Sulfate ◽  
Golgi Complex ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Hemorrhagic Fever ◽  
Cell Types ◽  
Fever Virus ◽  
Host Cells ◽  
Valley Fever

ABSTRACTRift Valley fever virus (RVFV) causes recurrent insect-borne epizootics throughout the African continent, and infection of humans can lead to a lethal hemorrhagic fever syndrome. Deep mutagenesis of haploid human cells was used to identify host factors required for RVFV infection. This screen identified a suite of enzymes involved in glycosaminoglycan (GAG) biogenesis and transport, including several components of thecis-oligomeric Golgi (COG) complex, one of the central components of Golgi complex trafficking. In addition, disruption ofPTAR1led to RVFV resistance as well as reduced heparan sulfate surface levels, consistent with recent observations that PTAR1-deficient cells exhibit altered Golgi complex morphology and glycosylation defects. A variety of biochemical and genetic approaches were utilized to show that both pathogenic and attenuated RVFV strains require GAGs for efficient infection on some, but not all, cell types, with the block to infection being at the level of virion attachment. Examination of other members of theBunyaviridaefamily for GAG-dependent infection suggested that the interaction with GAGs is not universal among bunyaviruses, indicating that these viruses, as well as RVFV on certain cell types, employ additional unidentified virion attachment factors and/or receptors.IMPORTANCERift Valley fever virus (RVFV) is an emerging pathogen that can cause severe disease in humans and animals. Epizootics among livestock populations lead to high mortality rates and can be economically devastating. Human epidemics of Rift Valley fever, often initiated by contact with infected animals, are characterized by a febrile disease that sometimes leads to encephalitis or hemorrhagic fever. The global burden of the pathogen is increasing because it has recently disseminated beyond Africa, which is of particular concern because the virus can be transmitted by widely distributed mosquito species. There are no FDA-licensed vaccines or antiviral agents with activity against RVFV, and details of its life cycle and interaction with host cells are not well characterized. We used the power of genetic screening in human cells and found that RVFV utilizes glycosaminoglycans to attach to host cells. This furthers our understanding of the virus and informs the development of antiviral therapeutics.

scholarly journals First Serological Evidence of Crimean-Congo Hemorrhagic Fever Virus and Rift Valley Fever Virus in Ruminants in Tunisia

Pathogens ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 769
Author(s):  
Khaoula Zouaghi ◽  
Ali Bouattour ◽  
Hajer Aounallah ◽  
Rebecca Surtees ◽  
Eva Krause ◽  
...  
Keyword(s):  
Risk Factors ◽  
Potential Risk ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Hemorrhagic Fever ◽  
Fever Virus ◽  
Valley Fever ◽  
Hemorrhagic Fever Virus ◽  
Potential Risk Factors

Crimean-Congo hemorrhagic fever virus (CCHFV, Nairoviridae family) and Rift Valley fever virus (RVFV, Phenuiviridae family) are zoonotic vector-borne pathogens with clinical relevance worldwide. Our study aimed to determine seroprevalences of these viruses and potential risk factors among livestock (cattle, sheep, and goats) in Tunisia. Sera were tested for antibodies against CCHFV (n = 879) and RVFV (n = 699) using various enzyme-linked immunosorbent assays (ELISAs) and indirect immunofluorescence assays (IIFA). The overall seroprevalence of IgG antibodies was 8.6% (76/879) and 2.3% (16/699) against CCHFV and RVFV, respectively. For CCHF seropositivity bioclimatic zones and breed were potential risk factors for the three tested animal species; while the season was associated with cattle and sheep seropositivity, tick infestation was associated with cattle and goats seropositivity and age as a risk factor was only associated with cattle seropositivity. Age and season were significantly associated with RVFV seropositivity in sheep. Our results confirm the circulation of CCHFV and RVFV in Tunisia and identified the principal risk factors in ruminants. This knowledge could help to mitigate the risk of ruminant infections and subsequently also human infections.

scholarly journals Generation and characterization of a recombinant Rift Valley fever virus expressing a V5 epitope-tagged RNA-dependent RNA polymerase

2011 ◽  
Vol 92 (12) ◽  
pp. 2906-2913 ◽  
Author(s):  
Benjamin Brennan ◽  
Ping Li ◽  
Richard M. Elliott
Keyword(s):  
Life Cycle ◽  
Rna Polymerase ◽  
Rift Valley ◽  
Rift Valley Fever ◽  
Rift Valley Fever Virus ◽  
Fever Virus ◽  
Rna Dependent Rna Polymerase ◽  
Valley Fever ◽  
L Protein ◽  
Infected Cells

The viral RNA-dependent RNA polymerase (RdRp; L protein) of Rift Valley fever virus (RVFV; family Bunyaviridae) is a 238 kDa protein that is crucial for the life cycle of the virus, as it catalyses both transcription of viral mRNAs and replication of the tripartite genome. Despite its importance, little is known about the intracellular distribution of the polymerase or its other roles during infection, primarily because of lack of specific antibodies that recognize L protein. To begin to address these questions we investigated whether the RVFV (MP12 strain) polymerase could tolerate insertion of the V5 epitope, as has been previously demonstrated for the Bunyamwera virus L protein. Insertion of the 14 aa epitope into the polymerase sequence at aa 1852 resulted in a polymerase that retained functionality in a minigenome assay, and we were able to rescue recombinant viruses that expressed the modified L protein by reverse genetics. The L protein could be detected in infected cells by Western blotting with anti-V5 antibodies. Examination of recombinant virus-infected cells by immunofluorescence revealed a punctate perinuclear or cytoplasmic distribution of the polymerase that co-localized with the nucleocapsid protein. The generation of RVFV expressing a tagged RdRp will allow detailed examination of the role of the viral polymerase in the virus life cycle.

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