The Experts below are selected from a list of 5490 Experts worldwide ranked by ideXlab platform
Ramon Flick - One of the best experts on this subject based on the ideXlab platform.
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Rift Valley fever virus.
Current Molecular Medicine, 2005Co-Authors: Ramon Flick, Michele BouloyAbstract:Rift Valley fever is considered to be one of the most important viral zoonoses in Africa. In 2000, the Rift valley fever virus spread to the Arabian Peninsula and caused two simultaneous outbreaks in Yemen and Saudi Arabia. It is transmitted to ruminants and to humans by mosquitoes. The viral agent is an arbovirus, which belongs to the Phlebovirus genus in the Bunyaviridae family. This family of viruses comprises more than 300 members grouped into five genera: Orthobunyavirus, Phlebovirus, Hantavirus, Nairovirus, and Tospovirus. Several members of the Bunyaviridae family are responsible for fatal hemorrhagic fevers: Rift Valley fever virus (Phlebovirus), Crimean-Congo hemorrhagic fever virus (Nairovirus), Hantaan, Sin Nombre and related viruses (Hantavirus), and recently Garissa, now identified as Ngari virus (Orthobunyavirus). Here are reviewed recent advances in Rift Valley fever virus, its epidemiology, molecular biology and focus on recent data on the interactions between viral and cellular proteins, which help to understand the molecular mechanisms utilized by the virus to circumvent the host cellular response.
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reverse genetics system for uukuniemi virus Bunyaviridae rna polymerase i catalyzed expression of chimeric viral rnas
Journal of Virology, 2001Co-Authors: Ramon Flick, Ralf F PetterssonAbstract:The procedures developed during the 1990s to genetically manipulate the genomes of negative-strand viruses and to rescue infectious viruses entirely from cloned cDNAs, commonly referred to as reverse genetics, have revolutionized the analyses of viral gene expression and the dissection of cis-acting regulatory sequences important for replication and transcription. They have also paved the road for engineering these viruses for vaccine and gene therapy purposes (6, 36). The ability to rescue infectious viruses from cloned cDNAs has by now been well established for nonsegmented, negative-strand viruses (Mononegavirales), such as members of the Rhabdoviridae (22, 41, 48) and Paramyxoviridae (1, 5, 18, 19, 35) families. The development of similar protocols for manipulating the genomes and creating viruses from cloned cDNAs of segmented, negative-strand viruses, i.e., members of the Orthomyxoviridae, Bunyaviridae, and Arenaviridae families, have turned out to be much more difficult. Although the ability to manipulate RNA segments of influenza A viruses was developed more than a decade ago (10, 25), it was not until last year that the first reports on the rescue of infectious influenza A virus entirely from cloned cDNAs were published (15, 20, 31, 32). Members of the Bunyaviridae family, which comprises more than 300 viruses (28) grouped into the five genera Bunyavirus, Hantavirus, Nairovirus, Phlebovirus, and Tospovirus, are enveloped viruses with a tripartite, single-stranded RNA genome of negative polarity. The L segment encodes the RNA-dependent RNA polymerase (L), the M segment encodes the two spike proteins (G1 and G2) and in some viruses a nonstructural protein (NSm), while the S segment encodes the nucleoprotein (N) and in some viruses a nonstructural protein (NSs) (8, 40). Initiation of transcription of the viral mRNAs is primed by short sequences derived from the 5′ end of host mRNAs (2, 40, 43). This cap-snatching mechanism is reminiscent of that first described for influenza virus (21), with the important difference that cap snatching occurs in the cytoplasm of Bunyaviridae-infected cells, as opposed to the nucleus in influenza virus-infected cells. This is due to the fact that Bunyaviridae members replicate exclusively in the cytoplasm. As is the case for all negative-strand RNA viruses, the templates for L polymerase-catalyzed replication and transcription of Bunyaviridae members are the ribonucleoproteins (RNPs) consisting of the full-length positive- or negative-strand RNA segments associated with the N protein. To date, methods to study the role of cis-acting sequences at the 5′ and 3′ termini of viral RNA (vRNA) segments have been developed for Bunyamwera (BUN) virus (Bunyavirus) (7) and Rift Valley fever (RVF) virus (Phlebovirus) (24, 34), using the now classical T7-vaccinia virus (T7-VV) system (16) to express a chloramphenicol acetyltransferase (CAT) reporter cDNA flanked by 5′ and 3′ vRNA ends. An important step was taken when Bridgen and Elliott in 1996 (4) were able to rescue infectious BUN virus entirely from cloned cDNAs, although the procedure was cumbersome and the efficiency of generating infectious virus was rather low. To look for an alternative approach for developing a reverse genetics system for Bunyaviridae, we have turned to the RNA polymerase I (pol I) expression system, which was recently successfully used to rescue infectious influenza virus (15, 31, 32). This system, originally developed by Hobom and coworkers (30, 49), has been used to study cis-acting sequences important for transcription and replication (14) and to develop a procedure for indirect selection of recombinant influenza viruses (12). An ambisense strategy to further simplify the procedure was recently reported (20). In the pol I system, cDNAs coding for viral RNA segments, or reporter genes flanked by viral sequences, are cloned between the RNA pol I promoter and terminator to generate transcripts that have correct 5′ and 3′ ends without modifications such as a cap structure and a poly(A) tail (12, 49). In the case of influenza virus, these pol I transcripts are then replicated and transcribed in the nucleus by the necessary viral proteins. Following transport of the RNPs to the cytoplasm, infectious particles are assembled by budding at the plasma membrane. We have adopted the pol I system to express reporter genes flanked by the 5′ and 3′ noncoding sequences of the M RNA segment of Uukuniemi (UUK) virus, a member of the Phlebovirus genus (28). We have previously characterized extensively the molecular and cell biology of UUK virus. Full-length cDNAs corresponding to the L (6,423 nucleotides [nt]) (9), M (3,229 nt) (38), and S (1,720 nt) (42) segments have been constructed, and cDNAs encoding the open reading frames (ORFs) for the L, G1, G2, N, and NSs proteins have been derived (9, 26, 37, 44). As the first step toward the generation of infectious virus from cloned cDNAs, we show here that the pol I system can be used to synthesize chimeric RNA templates, which, despite lacking a cap structure and poly(A) tail, are transported to the cytoplasm, where they are amplified and transcribed by the UUK virus replicase components supplied either by superinfection with UUK virus or by expression of viral proteins from separate plasmids. The L and N proteins were found to be necessary and sufficient for transcription and replication, while NSs was completely dispensable. We also show that CAT activity could be transferred serially from culture to culture by passaging supernatants from transfected and superinfected cells. This indicates that the chimeric reporter RNA could be packaged into virus particles. Thus, the pol I system holds great potential as an effective alternative approach for a versatile reverse genetics system for members of the Bunyaviridae family.
Michele Bouloy - One of the best experts on this subject based on the ideXlab platform.
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Rift Valley fever virus.
Current Molecular Medicine, 2005Co-Authors: Ramon Flick, Michele BouloyAbstract:Rift Valley fever is considered to be one of the most important viral zoonoses in Africa. In 2000, the Rift valley fever virus spread to the Arabian Peninsula and caused two simultaneous outbreaks in Yemen and Saudi Arabia. It is transmitted to ruminants and to humans by mosquitoes. The viral agent is an arbovirus, which belongs to the Phlebovirus genus in the Bunyaviridae family. This family of viruses comprises more than 300 members grouped into five genera: Orthobunyavirus, Phlebovirus, Hantavirus, Nairovirus, and Tospovirus. Several members of the Bunyaviridae family are responsible for fatal hemorrhagic fevers: Rift Valley fever virus (Phlebovirus), Crimean-Congo hemorrhagic fever virus (Nairovirus), Hantaan, Sin Nombre and related viruses (Hantavirus), and recently Garissa, now identified as Ngari virus (Orthobunyavirus). Here are reviewed recent advances in Rift Valley fever virus, its epidemiology, molecular biology and focus on recent data on the interactions between viral and cellular proteins, which help to understand the molecular mechanisms utilized by the virus to circumvent the host cellular response.
Summerpal Kahlon - One of the best experts on this subject based on the ideXlab platform.
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Viral Hemorrhagic Fever: Bunyaviridae
Current Treatment Options in Infectious Diseases, 2015Co-Authors: Summerpal KahlonAbstract:Viruses of the family Bunyaviridae cause a variety of human diseases. Some members of this family are known to cause hemorrhagic fever syndrome in humans. Included in this group are Crimean-Congo hemorrhagic fever and Hantaan virus-induced hemorrhagic fever with renal syndrome. Rift Valley fever (RVF), a viral hemorrhagic fever in this family, merits greater attention in awareness of diagnosis and treatment options. Once thought to be an unusual source of sporadic disease outbreaks in rural east Africa, RVF continues to emerge as a viral hemorrhagic fever of note. With greater health care access, improved awareness, and newer diagnostic techniques, cases increasingly continue to be identified primarily across Sub-Saharan Africa and the Arabian Peninsula. Early clinical suspicion and identification of disease are important to implementation of appropriate, effective therapy. Early-stage RVF mimics other common febrile illnesses, such as malaria. With increasing global travel, clinicians may encounter RVF both in its local endemic geography as well as in travelers from the region. Supportive care is the traditional primary therapy, though increasing knowledge of the disease suggests additional options for consideration of prevention and treatment. This review will focus on RVF with relevant reference to other viral hemorrhagic fevers in the family.
Shchelkanov Miu - One of the best experts on this subject based on the ideXlab platform.
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molecular genetic characterization of the gissar virus gsrv Bunyaviridae phlebovirus uukuniemi group isolated from the ticks argas reflexus fabricius 1794 argasidae collected in dovecote in tajikistan
Voprosy virusologii, 2014Co-Authors: D K Lvov, Shchelkanov Miu, S V Alkhovskiĭ, A M Shchetinin, V A Aristova, A K Gitelman, P G Deriabin, A G BotikovAbstract:The Gissar virus (GSRV) was originally isolated from the ticks Argas reflexus, Fabricius, 1794 collected in a dovecote of Gissar village in Tajikistan (38 degrees 40' N, 68 degrees 40' E). Using electron microscopy, GSRV was classified to Bunyaviridae without referring to genus due to the absence of the antigenic relation with known bunyaviruses. In the present paper genome of GSRV was sequenced (MiSeq, Illumina). Molecular genetics and phylogenetic analysis showed. GSRV has a high level of homology with the Grand Arbaud Virus (GAV) (94% for nucleocapsid protein, 87.5% for RdRp, and 82% for the envelope proteins GnGc) isolated from the ticks A. Reflexus in a dovecote in France. GSRV and GAV have a narrow ecological niche associated with the icks A. Reflexus and birds (predominantly Columbidae). According to the conducted study, GSRV is classified as the topotypic for Central Asia variant of GAV, Uukuniemi group, genuses of the Phlebovirus (Bunyaviridae) (ID GenBank KJ425423, KJ425424, KJ425425).
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Taxonomic status of the Burana virus (BURV) (Bunyaviridae, Nairovirus, Tamdy group) isolated from the ticks Haemaphysalis punctata Canestrini et Fanzago, 1877 and Haem. concinna Koch, 1844 (Ixodidae, Haemaphysalinae) in Kyrgyzstan
Voprosy virusologii, 2014Co-Authors: Shchelkanov MiuAbstract:Complete genome sequence of the Burana virus (BURV) was determined using the next-generation sequencing approach (ID GenBank KF801651). The prototype strain of BURV LEIV-Krg760 was originally isolated from the ticks Haemaphysalis punctata Canestrini et Fanzago, 1877 (Ixodidae, Haemaphysalinae), collected from cows in Tokmak wildlife sanctuary, eastern part of the Chu valley (43 degrees 10' N, 74 degrees 40' E) near Burana village, Kirgizia, in April 1971. Molecular genetics and phylogenetic analyses showed that the BURV belonged to the Nairovirus genus, Bunyaviridae and is related to Tamdy virus (TAMV) that is also associated with the ixodidae ticks of pasture biocenosis in Central Asia. Previous studies showed that TAMV is the prototypic virus of new phylogenetic Tamdy group in the Nairovirus genus. Thus, BURV was classified as a new virus of the Tamdy group, Nairovirus, Bunyaviridae.
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Taxonomic status of the Artashat virus (ARTSV) (Bunyaviridae, Nairovirus) isolated from the ticks Ornithodoros alactagalis Issaakjan, 1936 and O. verrucosus Olenev, Sassuchin et Fenuk, 1934 (Argasidae Koch, 1844) collected in Transcaucasia
Voprosy virusologii, 2014Co-Authors: Shchelkanov MiuAbstract:The Artashat virus (ARTSV) was originally isolated fom the Ornithodoros alactagalis Issaakjan, 1936 (Argasidae Koch, 1844), which were collected in the burrow of small five-toed jerboa (Allactaga elater Lichtenstein, 1825) in Armenia in 1972. Later, the ARTSV was isolated from the O. verrucosus Olenev, Sassuchin et Fenuk, 1934 collected in the burrows of Persian gerbil (Meriones persicus Blanford, 1875) in Azerbaijan. Based on the virion morphology, the ARTSV was assigned to the Bunyaviridae viruses. In this work, the ARTSV genome was partially sequenced (GenBank ID: KF801650) and it was shown that the ARTSV is a new member of the Nairovirus genus. ARTSV has from 42% (Issyk-Kul virus) to 58% (Raza virus, Hughes group) similarity with the nairoviruses for nucleotide sequence of part of RNA-dependent RNA-polymerase (RdRp). The similarity on the amino acid level is 65-70%. Low level of homology and the equidistant position of the ARTSV on phylogenetic tree indicate that the ARTSV is a new prototype species of the Nairovirus genus (Bunyaviridae) forming a separate phylogenetic branch.
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Genetic characterization of the Sakhalin virus (SAKV), Paramushir virus (PMRV) (Sakhalin group, Nairovirus, Bunyaviridae), and Rukutama virus (RUKV) (Uukuniemi group, Phlebovirus, Bunyaviridae) isolated from the obligate parasites of the colonial sea
Voprosy virusologii, 2014Co-Authors: Shchelkanov MiuAbstract:Full-length genomes of the Sakhalin virus (SAKH) and Paramushir virus (PRMV) (Sakhalin group, Nairovirus, Bunyaviridae) isolated from the ticks Ixodes uriae White 1852 were sequenced using the next-generation sequencing (Genbank ID: KF801659, KF801656). SAKV and PRMV have 81% identity for the part of RNA-dependent RNA-polymerase (RdRp) on the nucleotide level and 98.5% on the amino acid level. Full-length genome comparison shows that SAKV have, in average, from 25% (N-protein, S-segment) to 50% (RdRp, L-segment) similarity with the nairoviruses. The maximum value of the amino acid similarity (50.3% for RdRp) SAKV have with the Crimean-Congo hemorrhagic fever virus (CCHFV) and Dugbe virus (DUGV), which are also associated with the Ixodidae ticks. Another virus studied is Rukutama virus (RUKV) (isolated from ticks I. signatus Birulya, 1895) that recently was classified (based on morphology and antigenic reaction) to the Nairovirus genus, presumably to the Sakhalin group. In this work the genome of the RUKV was sequenced (KF892052-KF892054) and RUKV was classified as a member of the Uukuniemi group (Phlebovirus, Bunyaviridae). RUKV is closely related (93.0-95.5% similarity) with our previously described Komandory virus (KOMV). RUKV and KOMV form separate phylogenetic line neighbor of Manawa virus (MWAV) isolated from the ticks Argas abdussalami Hoogstraal et McCarthy, 1965 in Pakistan. The value of the similarity between RUCV and MWAV is 65-74% on the amino acid level.
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Genetic characterization of the Caspiy virus (CASV) (Bunyaviridae, Nairovirus) isolated from the Laridae (Vigors, 1825) and Sternidae (Bonaparte, 1838) birds and the Argasidae (Koch, 1844) ticks Ornithodoros capensis Neumann, 1901, in Western and Eas
Voprosy virusologii, 2014Co-Authors: Shchelkanov MiuAbstract:Full-genome sequencing of the Caspiy virus (CASV - Caspiy virus) (ID GenBank KF801658) revealed its attribution to the Nairovirus genus of the Bunyaviridae family as a separate species. CASV forms separate line, which is the most close to the Hughes virus (HUGV) and Sakhalin virus (SAKV) groups containing viruses linked with seabirds and ticks parasitizing on them and distributed over the shelf and island ecosystems in the Northern Eurasia, as well as the North and South America.
Francisco Gonzalezscarano - One of the best experts on this subject based on the ideXlab platform.
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chapter 21 the Bunyaviridae
Handbook of Clinical Neurology, 2014Co-Authors: Samantha S. Soldan, Francisco GonzalezscaranoAbstract:The Bunyaviridae is a large and diverse family of viruses whose members infect a wide range of arthropod vectors and animal or plant hosts. Bunyaviruses are distributed worldwide and their promiscuous use of an impressive variety of arthropod vectors amplifies the potential for bunyaviruses to increase their prevalence and geographic range given the right environmental or man-made conditions. Most bunyavirus infections are asymptomatic or present with a mild influenza-like illness. However, some members of the family are important human and veterinary pathogens that are the causative agents of devastating illnesses, including hemorrhagic fever, pulmonary disease, congenital abnormalities, and fatal encephalitis. In this chapter, we discuss the epidemiology, lifecycle, molecular biology, neuropathogenesis, and prevention and treatment strategies for emerging bunyaviruses that are predominantly associated with central nervous disease; these include members of the genera Phlebovirus (Rift Valley fever virus and Toscana virus) and Orthobunyavirus (La Crosse virus and Cache Valley virus).
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short communicationcompletion of the la crosse virus genome sequence and geneticcomparisons of the l proteins of the Bunyaviridae
Virology, 1995Co-Authors: Anjeanette Roberts, Colette Rossier, Neal Nathanson, Dan Kolakofsky, Francisco GonzalezscaranoAbstract:La Crosse virus is a member of the Bunyavirus genus in the family Bunyaviridae, viruses with trisegmented RNA genomes of mostly negative polarity composed of large (L), medium (M), and small (S) segments. The sequences of the La Crosse/ original M and S RNA segments have been previously characterized. Using reverse transcriptase in conjunction with PCR amplification, we have obtained the nucleotide sequence of the L RNA segment, which encodes the viral polymerase in a single large open reading frame. Comparison of the amino acid sequence of the LAC L protein with the sequence of other polymerases from members of the Bunyaviridae, demonstrated the presence of several conserved motifs, some of which are characteristic of many polymerase proteins. A genetic tree comparing the available polymerase proteins of the Bunyaviridae provides insights into the phylogenetic relationships within this large family. Members of the genus Bunyavirus, which are mosquito-borne and infect mammals, have a closer relationship to the plant viruses represented by tomato spotted wilt virus (Tospovirus genus) than to viruses of other genera in the family Bunyaviridae.
