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The New England Journal of Medicine Apr 2011Heightened surveillance of acute febrile illness in China since 2009 has led to the identification of a severe fever with thrombocytopenia syndrome (SFTS) with an...
BACKGROUND
Heightened surveillance of acute febrile illness in China since 2009 has led to the identification of a severe fever with thrombocytopenia syndrome (SFTS) with an unknown cause. Infection with Anaplasma phagocytophilum has been suggested as a cause, but the pathogen has not been detected in most patients on laboratory testing.
METHODS
We obtained blood samples from patients with the case definition of SFTS in six provinces in China. The blood samples were used to isolate the causal pathogen by inoculation of cell culture and for detection of viral RNA on polymerase-chain-reaction assay. The pathogen was characterized on electron microscopy and nucleic acid sequencing. We used enzyme-linked immunosorbent assay, indirect immunofluorescence assay, and neutralization testing to analyze the level of virus-specific antibody in patients' serum samples.
RESULTS
We isolated a novel virus, designated SFTS bunyavirus, from patients who presented with fever, thrombocytopenia, leukocytopenia, and multiorgan dysfunction. RNA sequence analysis revealed that the virus was a newly identified member of the genus phlebovirus in the Bunyaviridae family. Electron-microscopical examination revealed virions with the morphologic characteristics of a bunyavirus. The presence of the virus was confirmed in 171 patients with SFTS from six provinces by detection of viral RNA, specific antibodies to the virus in blood, or both. Serologic assays showed a virus-specific immune response in all 35 pairs of serum samples collected from patients during the acute and convalescent phases of the illness.
CONCLUSIONS
A novel phlebovirus was identified in patients with a life-threatening illness associated with fever and thrombocytopenia in China. (Funded by the China Mega-Project for Infectious Diseases and others.).
Topics: Adult; Aged; Aged, 80 and over; Animals; Antibodies, Viral; Bunyaviridae Infections; China; Communicable Diseases, Emerging; Female; Fever; Genome, Viral; Humans; Ixodidae; Male; Microscopy, Electron, Transmission; Middle Aged; Orthobunyavirus; Phylogeny; RNA, Viral; Reverse Transcriptase Polymerase Chain Reaction; Thrombocytopenia
PubMed: 21410387
DOI: 10.1056/NEJMoa1010095 -
Viruses Nov 2014The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are... (Review)
Review
The Bunyaviridae family is comprised of more than 350 viruses, of which many within the Hantavirus, Orthobunyavirus, Nairovirus, Tospovirus, and Phlebovirus genera are significant human or agricultural pathogens. The viruses within the Orthobunyavirus, Nairovirus, and Phlebovirus genera are transmitted by hematophagous arthropods, such as mosquitoes, midges, flies, and ticks, and their associated arthropods not only serve as vectors but also as virus reservoirs in many cases. This review presents an overview of several important emerging or re-emerging bunyaviruses and describes what is known about bunyavirus-vector interactions based on epidemiological, ultrastructural, and genetic studies of members of this virus family.
Topics: Animals; Arthropod Vectors; Arthropods; Bunyaviridae Infections; Host-Pathogen Interactions; Humans; Orthobunyavirus
PubMed: 25402172
DOI: 10.3390/v6114373 -
Nature Communications Oct 2023The severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne human-infecting bunyavirus, which utilizes two envelope glycoproteins, Gn and Gc, to enter...
The severe fever with thrombocytopenia syndrome virus (SFTSV) is a tick-borne human-infecting bunyavirus, which utilizes two envelope glycoproteins, Gn and Gc, to enter host cells. However, the structure and organization of these glycoproteins on virion surface are not yet known. Here we describe the structure of SFTSV determined by single particle reconstruction, which allows mechanistic insights into bunyavirus assembly at near-atomic resolution. The SFTSV Gn and Gc proteins exist as heterodimers and further assemble into pentameric and hexameric peplomers, shielding the Gc fusion loops by both intra- and inter-heterodimer interactions. Individual peplomers are associated mainly through the ectodomains, in which the highly conserved glycans on N914 of Gc play a crucial role. This elaborate assembly stabilizes Gc in the metastable prefusion conformation and creates some cryptic epitopes that are only accessible in the intermediate states during virus entry. These findings provide an important basis for developing vaccines and therapeutic drugs.
Topics: Humans; Viral Envelope Proteins; Severe Fever with Thrombocytopenia Syndrome; Cryoelectron Microscopy; Phlebovirus; Glycoproteins; Orthobunyavirus
PubMed: 37816705
DOI: 10.1038/s41467-023-41804-7 -
Autophagy Jul 2022Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging negatively stranded enveloped RNA bunyavirus that causes SFTS with a high case fatality rate of...
Severe fever with thrombocytopenia syndrome virus (SFTSV) is an emerging negatively stranded enveloped RNA bunyavirus that causes SFTS with a high case fatality rate of up to 30%. Macroautophagy/autophagy is an evolutionarily conserved process involved in the maintenance of host homeostasis, which exhibits anti-viral or pro-viral responses in reaction to different viral challenges. However, the interaction between the bunyavirus SFTSV and the autophagic process is still largely unclear. By establishing various autophagy-deficient cell lines, we found that SFTSV triggered RB1CC1/FIP200-BECN1-ATG5-dependent classical autophagy flux. SFTSV nucleoprotein induced BECN1-dependent autophagy by disrupting the BECN1-BCL2 association. Importantly, SFTSV utilized autophagy for the viral life cycle, which not only assembled in autophagosomes derived from the ERGIC and Golgi complex, but also utilized autophagic vesicles for exocytosis. Taken together, our results suggest a novel virus-autophagy interaction model in which bunyavirus SFTSV induces classical autophagy flux for viral assembly and egress processes, suggesting that autophagy inhibition may be a novel therapy for treating or releasing SFTS.
Topics: Autophagy; Humans; Orthobunyavirus; Phlebovirus; Severe Fever with Thrombocytopenia Syndrome; Virus Assembly
PubMed: 34747299
DOI: 10.1080/15548627.2021.1994296 -
PLoS Pathogens Jan 2023Bunyaviruses are negative sense, single-strand RNA viruses that infect a wide range of vertebrate, invertebrate and plant hosts. WHO lists three bunyavirus diseases as... (Review)
Review
Bunyaviruses are negative sense, single-strand RNA viruses that infect a wide range of vertebrate, invertebrate and plant hosts. WHO lists three bunyavirus diseases as priority diseases requiring urgent development of medical countermeasures highlighting their high epidemic potential. While the viral large (L) protein containing the RNA-dependent RNA polymerase is a key enzyme in the viral replication cycle and therefore a suitable drug target, our knowledge on the structure and activities of this multifunctional protein has, until recently, been very limited. However, in the last few years, facilitated by the technical advances in the field of cryogenic electron microscopy, many structures of bunyavirus L proteins have been solved. These structures significantly enhance our mechanistic understanding of bunyavirus genome replication and transcription processes and highlight differences and commonalities between the L proteins of different bunyavirus families. Here, we provide a review of our current understanding of genome replication and transcription in bunyaviruses with a focus on the viral L protein. Further, we compare within bunyaviruses and with the related influenza virus polymerase complex and highlight open questions.
Topics: Bunyaviridae; Orthobunyavirus; RNA; Viral Proteins; Virus Replication
PubMed: 36634042
DOI: 10.1371/journal.ppat.1011060 -
Viruses Sep 2022Bunyaviruses represent the largest group of RNA viruses and are the causative agent of a variety of febrile and hemorrhagic illnesses. Originally characterized as a... (Review)
Review
Bunyaviruses represent the largest group of RNA viruses and are the causative agent of a variety of febrile and hemorrhagic illnesses. Originally characterized as a single serotype in Africa, the number of described bunyaviruses now exceeds over 500, with its presence detected around the world. These predominantly tri-segmented, single-stranded RNA viruses are transmitted primarily through arthropod and rodent vectors and can infect a wide variety of animals and plants. Although encoding for a small number of proteins, these viruses can inflict potentially fatal disease outcomes and have even developed strategies to suppress the innate antiviral immune mechanisms of the infected host. This short review will attempt to provide an overall description of the order , describing the mechanisms behind their infection, replication, and their evasion of the host immune response. Furthermore, the historical context of these viruses will be presented, starting from their original discovery almost 80 years ago to the most recent research pertaining to viral replication and host immune response.
Topics: Animals; Bunyaviridae; Orthobunyavirus; Virus Replication; RNA Viruses; Antiviral Agents
PubMed: 36298693
DOI: 10.3390/v14102139 -
Viruses May 2022Dozens of orthobunyaviruses have been isolated in Brazil, and at least thirteen have been associated with human disease. The Oropouche virus has received most attention... (Review)
Review
Dozens of orthobunyaviruses have been isolated in Brazil, and at least thirteen have been associated with human disease. The Oropouche virus has received most attention for having caused explosive epidemics with hundreds of thousands of cases in the north region between the 1960sand the 1980s, and since then has been sporadically detected elsewhere in the country. Despite their importance, little is known about their enzootic cycles of transmission, amplifying hosts and vectors, and biotic and abiotic factors involved in spillover events to humans. This overview aims to combine available data of neglected orthobunyaviruses of several serogroups, namely, Anopheles A, Anopheles B, Bunyamwera, California, Capim, Gamboa, Group C, Guama, Simbu and Turlock, in order to evaluate the current knowledge and identify research gaps in their natural transmission cycles in Brazil to ultimately point to the future direction in which orthobunyavirus research should be guided.
Topics: Animals; Anopheles; Brazil; Humans; Mosquito Vectors; Orthobunyavirus; Serogroup
PubMed: 35632729
DOI: 10.3390/v14050987 -
Uirusu 2012The family Bunyaviridae consists of over 300 virus species and strains that are divided into 5 genera: orthobunyavirus, hantavirus, nairovirus, phlebovirus, and... (Review)
Review
The family Bunyaviridae consists of over 300 virus species and strains that are divided into 5 genera: orthobunyavirus, hantavirus, nairovirus, phlebovirus, and tospovirus. All members of family Bunyaviridae possess a negative-sense, single stranded tripartite RNA genome, consisting of large (L), medium (M) and small (S) segments, which encode an RNA-dependent RNA polymerase, two envelope glyoproteins (Gn and Gc) and nucleocapsid (N) protein, respectively. Insects and arthropods serve as vectors of viruses in the Bunyaviridae, except for hantviruses, which instead are harbored by rodents. However, phylogenetically distinct soricomorph-associated hantaviruses have been discovered in widely separated geographical regions spanning four continents. This new finding strongly suggests that evolutionary record of hantaviruses is far more complex and ancient than originally expected. Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease recently described in northeast and central China. The causative agent of SFTS is phylogenetically classified to genus phlebivirus, but unlike to other member in genus phlebovirus, SFTV transmit by ticks. This review provides a brief overview of hantavirus and hantavirus infection and describes about two newly appeared viruses in the family Bunyaviridae.
Topics: Animals; Bunyaviridae Infections; Genome, Viral; Humans; Orthobunyavirus; Phlebovirus; Phylogeny; RNA, Viral; Viral Structural Proteins; Virus Replication; Zoonoses
PubMed: 24153234
DOI: 10.2222/jsv.62.239 -
Trends in Microbiology Apr 2020In common with all segmented negative-sense RNA viruses, bunyavirus transcripts contain heterologous sequences at their 5' termini originating from capped host cell... (Review)
Review
In common with all segmented negative-sense RNA viruses, bunyavirus transcripts contain heterologous sequences at their 5' termini originating from capped host cell RNAs. These heterologous sequences are acquired by a so-called cap-snatching mechanism. Whereas for nuclear replicating influenza virus the source of capped primers as well as the cap-binding and endonuclease activities of the viral polymerase needed for cap snatching have been functionally and structurally well characterized, our knowledge on the expected counterparts of cytoplasmic replicating bunyaviruses is still limited and controversial. This review focuses on the cap-snatching mechanism of bunyaviruses in the light of recent structural and functional data.
Topics: Endonucleases; Orthobunyavirus; Orthomyxoviridae; RNA Caps; RNA, Viral; Transcription, Genetic; Viral Proteins; Virus Replication
PubMed: 31948728
DOI: 10.1016/j.tim.2019.12.006 -
Viruses Aug 2022Batai virus (BATV) is a zoonotic orthobunyavirus transmitted by a wide range of mosquito vectors. The virus is distributed throughout Asia and parts of Africa and has... (Review)
Review
Batai virus (BATV) is a zoonotic orthobunyavirus transmitted by a wide range of mosquito vectors. The virus is distributed throughout Asia and parts of Africa and has been sporadically detected in several European countries. There is increasing evidence that BATV is emerging in Europe as a potential threat to both animal and human health, having been detected in mosquitoes, mammals, birds and humans. In recent years, serological surveillance in cattle, sheep and goats has suggested an antibody prevalence of up to 46% in European livestock, although human serological prevalence remains generally low. However, the recent and continued spread of invasive mosquito species into Europe may facilitate the establishment of competent populations of mosquitoes leading to increased BATV transmission. Migratory birds may also potentially facilitate the emergence of BATV in geographical locations where it was previously undetected. Although BATV has the potential to cause disease in humans and livestock, our understanding of the impact in wild animal populations is extremely limited. Therefore, there is a need for increased surveillance for BATV in mosquitoes, livestock, wild mammals and birds in Europe to understand the true impact of this virus.
Topics: Animals; Bunyamwera virus; Cattle; Culicidae; Europe; Goats; Humans; Orthobunyavirus; Phylogeny; Sheep
PubMed: 36146674
DOI: 10.3390/v14091868