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PubMed1985

The proteins and RNAs specified by Clo Mor virus, a Scottish Nairovirus.

The proteins and RNAs of Clo Mor virus have been analysed. Virus-specific proteins in infected cells had previously been identified by isotopic labelling and radioimmunoprecipitation; these were three glycoproteins (mol. wt. 115K, 90K and 80K) and an unglycosylated nucleocapsid (N) protein (50K). We have performed pulse-chase experiments which indicated that the 115K protein is processed to give the 90K and 80K proteins, while a 45K protein was detected in released virions after prolonged chase. Translation in vitro of mRNA extracted from Clo Mor virus-infected cells resolved only the N protein. Three species of RNA were extracted from Clo Mor virus intracellular nucleocapsids and have been designated L (11000 to 13000 bases), M (6300 bases) and S (1900 bases). The processing of viral proteins and the sizes of RNAs are characteristic of the Nairovirus genus of the family Bunyaviridae.

Bunyaviridae↗
PubMedDate not supplied

[The isolation of Dhori viruses (Orthomyxoviridae, Thogotovirus) and Crimean-Congo hemorrhagic fever virus (Bunyaviridae, Nairovirus) from the hare (Lepus europaeus) and its ticks Hyalomma marginatum in the middle zone of the Volga delta, Astrakhan region, 2001].

In August, 2001, in the middle zone of the delta of the Volga River, the Astrakhan region, during investigation of the natural foci of West Nile fever and Crimean--Congo hemorrhagic fever (CCHF), the material from the hare (Lepus europaeus, Pallas, 1778 (Lagomorpha, Leporidae) and collected from it the ticks Hyalomna marginatum Koch 1844, was obtained. 4 strains of Dhori virus (Orthomyxoviridae, Thogotovirus) and 2 strains of CCHF virus (Bunyaviridae, Nairovirus) were isolated. This is the first isolation of Thogotovirus genus virus from the wild vertebrates. Considering the overlap of the Dhori virus and CCHF virus areas, similar ecology and the isolation both viruses from the same pool of the ticks, the necessity for the use of the test-system for indication of the viruses, differential diagnosis and accumulation of the data concerning the role of Dhori virus in the human and farm animals pathology is discussed.

Animals↗
PubMed1987

Field and laboratory investigation of Crimean-Congo haemorrhagic fever virus (Nairovirus, family Bunyaviridae) infection in birds.

In November 1984 a case of Crimean-Congo haemorrhagic fever (CCHF) occurred in a worker who became ill after slaughtering ostriches (Struthio camelus) on a farm near Oudtshoorn in the Cape province of South Africa. The diagnosis was confirmed by isolation of CCHF virus from the patient's serum and by demonstration of a specific antibody response. It was suspected that infection was acquired either by contact with ostrich blood or by inadvertently crushing infected Hyalomma ticks while skinning ostriches. Reversed passive haemagglutination-inhibition antibody to CCHF virus was detected in the sera of 22/92 ostriches from farms in Oudtshoorn district, including 6/9 from the farm where the patient worked, but not in the sera of 460 birds of 37 other species. In pathogenicity studies domestic chickens proved refractory to CCHF infection, but viraemia of low intensity (maximum titre 2.5 log10 mouse ic LD50/ml) followed by a transient antibody response occurred in blue-helmeted guinea fowl (Numidia meleagris). These results offer the first direct evidence that some bird species are susceptible to CCHF virus infection.

Animals↗
PubMed1989

Difference in vector competence of two species of sympatric ticks, Amblyomma variegatum and Rhipicephalus appendiculatus, for Dugbe virus (Nairovirus, Bunyaviridae).

Amblyomma variegatum was shown to be a competent vector of Dugbe (DUG) virus whereas Rhipicephalus appendiculatus was not. When DUG virus was taken up orally by A. variegatum nymphs, during capillary feeding, the virus replicated and persisted through moulting to the following adult stage. In contrast, although DUG virus replicated in capillary fed R. appendiculatus nymphs, the virus did not persist trans-stadially into the adult stage. If the oral route of infection was by-passed by direct inoculation into the haemocoel, DUG virus replicated and survived trans-stadially in both tick species, and was subsequently transmitted during feeding. The different responses of R. appendiculatus to oral and intra-coelomic routes suggest that DUG virus is able to infect the gut of this tick species, but that release of the virus from the gut is inhibited.

Animals↗
PubMed1983

Immunofluorescence studies on the antigenic interrelationships of the Hughes virus serogroup (genus Nairovirus) and identification of a new strain.

Titrations of hyperimmune antisera by indirect immunofluorescence using each virus of the Hughes serogroup (Hughes, Zirqa, Punta Salinas, Soldado and Farallon) demonstrated their individual antigenic identities. Furthermore, an antigenically related virus, designated Puffin Island (PI) virus, was shown both by indirect immunofluorescence and by neutralization in XTC cells to be distinguishable from the other viruses. These viruses readily established persistent infections in Vero cells after producing only moderate cytopathic effects. Treatment of persistently infected cultures with either fluorodeoxyuridine or bromodeoxyuridine made no significant difference to the percentage of immunofluorescent cells. Attempts to demonstrate haemagglutination by Zirqa virus were unsuccessful.

Antigens, Viral↗
PubMed1985

Experimental studies on the replication and dissemination of Qalyub virus (Bunyaviridae: Nairovirus) in the putative tick vector, Ornithodoros (Pavlovskyella) erraticus.

A study was undertaken to determine if the argasid tick, Ornithodoros (Pavlovskyella) erraticus, can serve as a biological vector of Qalyub (QYB) virus. The suckling mice used as viremic vertebrate hosts were acceptable hosts for all feeding stages of this tick and developed relatively high titered viremias (4.4-6.5 log10PFU/ml) 24-120 hr post intracerebral inoculation. Larval, nymphal, and adult ticks became orally infected with QYB virus after ingesting 4.4-6.4 log10PFU/ml. The overall infection rate for all experiments was 67/205 and virus was recovered up to day 179 postfeeding. Incubation of known quantities of QYB virus with uninfected triturated tick tissues did not result in any appreciable virus inactivation. QYB viral antigen was detected by immunofluorescence primarily in the tick midgut posterior diverticula cells. First and second instar nymphs orally infected as larvae did not individually transmit QYB virus to suckling mice; however they successfully transmitted the virus when feeding in groups of 11-20 per mouse. Three out of fourteen of the orally-infected male and female ticks individually transmitted QYB virus orally to suckling mice. Organ titrations of ticks orally exposed to QYB virus demonstrated virus primarily in midgut tissues; dissemination to other organ systems was discovered in only 1 tick after 142 days extrinsic incubation. Vertical transmission of virus from infected female ticks to progeny was not demonstrated. Four of the 39 ticks in our colony were infected with a spirochete; presumably, Borrelia crocidurae. O. (P.) erraticus apparently satisfies the conditions that would implicate this species as a biological vector of QYB virus and is the only known arthropod from which this virus has been isolated in nature.

Animals↗
PubMed1989

Experimental infection of six species of ixodid ticks with Dugbe virus (family Bunyaviridae, genus Nairovirus).

The vector potential of each of 6 species of colonized North American and African ixodid ticks was assessed by intracoelomic inoculation with Dugbe virus (IbAr 1792, 14th passage in suckling mouse brain) and viral titers were monitored after selected incubation periods. Persistence of Dugbe virus for greater than or equal to 53 days in 5 species (Dermacentor andersoni, D. variabilis, Amblyomma americanum, Rhipicephalus appendiculatus, and R. sanguineus) indicates that infection occurred. Viral titers were significantly higher in female vs. male D. variabilis, R. appendiculatus, and A. americanum after blood feeding. Blood feeding had no significant effect on the viral titers of either female or male R. sanguineus. D. andersoni males also exhibited no significant change in viral titers after blood-feeding, but 100% (20/20) of drop-off females and 96% (24/25) of post-oviposition females (36 days postinoculation) contained no detectable virus even though virus was still found in unfed specimens less than or equal to 124 days postinoculation. Virus was not recovered from greater than 30,000 1st generation progeny (eggs, larvae, nymphs, adults) collected as eggs from inoculated female D. andersoni, D. variabilis, R. sanguineus, and R. appendiculatus 27-51 days postinoculation. R. sanguineus and R. appendiculatus transmitted Dugbe virus to guinea pigs when allowed to feed 1-3 weeks postinoculation.

Africa↗
PubMed1991

Dissemination, replication, and trans-stadial persistence of Dugbe virus (Nairovirus, Bunyaviridae) in the tick vector Amblyomma variegatum.

The dissemination and replication of Dugbe (DUG) virus and its tissue tropisms in the tick vector Amblyomma variegatum were examined by immunohistochemical analysis using specific antibody, in situ hybridization with a viral-complementary riboprobe, and infectivity assays of dissected tissues. Dugbe virus was localized in both unfed and feeding adults inoculated as nymphs or orally infected by capillary feeding, and in nymphs infected by capillary feeding. In non-feeding ticks, the main sites of DUG virus replication were the epidermis, hemocytes associated with loose connective tissue, and a small number of phagocytic digestive cells in the gut lumen. Virus infectivity in the hemolymph was associated entirely with hemocytes. Dugbe viral antigen or infectivity was not detected in the salivary glands until after the start of feeding. Viral titers in the salivary glands of feeding ticks were about ten-fold higher than in gut, ovary, or loose connective tissue. The level of infection decreased during molting and increased during feeding. Viral particles and pathologic effects were not detected in infected ticks. The primary site of trans-stadial persistence of DUG virus is the hemocytes. Tick hemocytes and other motile cells may be important in the transmission of persistent virus infection from one cell or organ to another by diapedesis.

Animals↗
PubMed1986

Avalon virus, Sakhalin group (Nairovirus, Bunyaviridae) from the seabird tick Ixodes (Ceratixodes) uriae White 1852 in France.

Nine strains of Avalon virus were isolated from Ixodes uriae ticks collected in the Cape Sizun seabird reserve, Brittany, from 1979 to 1985, during a longitudinal study of consequences of tick-borne infections for kittiwakes (Rissa tridactyla). Avalon virus strains isolated in France proved difficult to study owing to the weak infectious titres they exhibited in suckling mice or cultured cells. However, some interesting data concerning the ecology of virus infection and the morphology of the virions were obtained and are discussed.

Animals↗
PubMed1983

Antigenic variants of the Soldado virus (Nairovirus, Bunyaviridae) isolated in different parts of the world.

Antigenic analysis of 9 strains of the Soldado virus, originating from seven different countries of Central and Northern America, Africa, Northern Europe and of the Pacific area was carried out by means of complement fixation (CF) and immunodiffusion (ID) tests. Three strains isolated from Ornithodoros (A.) capensis, including the reference Trinidad strain, were found to be related within the same relatively heterogeneous sub-group C, being characteristic for the New World. Five other strains isolated from Ornithodoros (A.) maritimus were classified to form an another, much more homogeneous subgroup M, characteristic for the Old World (related to the Ireland strain). The South Africa strain, isolated form Ornithodoros (A.), probably capensis, could not be classified in either of the above two subgroups. Thus, the Soldado virus in fact represents a complex of more or less closely related strains, but not a single virus.

Antigens, Viral↗
PubMed2004

Crimean-Congo hemorrhagic fever virus genome L RNA segment and encoded protein.

Sequence analysis of the L RNA genome segment and predicted encoded L polymerase protein of Crimean-Congo hemorrhagic fever (CCHF) virus (genus Nairovirus, family Bunyaviridae) demonstrates that they are approximately twice the size of those found in viruses of other bunyavirus genera. The CCHF virus L segment and encoded protein (12,164 nucleotides and 3944 amino acids, respectively) are similar in size and sequence to those of the nairovirus Dugbe virus (12,255/62% and 4036/62% nucleotide and amino acid length/identity, respectively). The identification of an ovarian tumor (OTU)-like protease motif in the L protein amino termini of the nairoviruses Dugbe, CCHF, and Nairobi sheep disease (NSD) indicates these proteins are members of the recently described OTU-like protease family and suggests that these large proteins may be polyproteins that are autoproteolytically cleaved or involved in deubiquitination.

Amino Acid Motifs↗
PubMed1992

Comparison of the S RNA segments and nucleoprotein sequences of Crimean-Congo hemorrhagic fever, Hazara, and Dugbe viruses.

The S RNA segments of the nairoviruses Crimean-Congo hemorrhagic fever (CCHF) virus (Chinese isolate) and Hazara (HAZ) virus were cloned and sequenced from PCR products. The RNAs comprise 1672 and 1677 nucleotides, respectively, and each encodes a protein in the viral complementary strand (54.0 and 54.2 kDa, respectively). The deduced protein sequences show homology to each other and to the nucleoprotein of Dugbe (DUG) nairovirus, although both the CCHF and HAZ viral proteins are larger. Alignment of the nucleoprotein sequences of CCHF, HAZ, and DUG viruses show that the CCHF and HAZ sequences are somewhat more closely related to each other (60.0% identity) than either is to the DUG sequence (55.4 and 53.0% identity, respectively); 39.5% of residues are identical across all three proteins. The carboxyl-terminus of DUG N protein shows a 40-residue deletion relative to the N proteins of the other two viruses.

Amino Acid Sequence↗
PubMed2002

Characterization of the glycoproteins of Crimean-Congo hemorrhagic fever virus.

Crimean-Congo hemorrhagic fever (CCHF) virus is the cause of an important tick-borne disease of humans throughout regions of Africa, Europe, and Asia. Like other members of the genus Nairovirus, family Bunyaviridae, the CCHF virus M genome RNA segment encodes the virus glycoproteins. Sequence analysis of the CCHF virus (Matin strain) M RNA segment revealed one major open reading frame that potentially encodes a precursor polyprotein 1,689 amino acids (aa) in length. Comparison of the deduced amino acid sequences of the M-encoded polyproteins of Nigerian, Pakistani, and Chinese CCHF virus strains revealed two distinct protein regions. The carboxyl-terminal 1,441 aa are relatively highly conserved (up to 8.4% identity difference), whereas the amino-terminal 243 to 248 aa are highly variable (up to 56.4% identity difference) and have mucin-like features, including a high serine, threonine, and proline content (up to 47.3%) and a potential for extensive O-glycosylation. Analysis of released virus revealed two major structural glycoproteins, G2 (37 kDa) and G1 (75 kDa). Virus protein analysis by various techniques, including pulse-chase analysis and/or reactivity with CCHF virus-specific polyclonal and antipeptide antibodies, demonstrated that the 140-kDa (which contains the mucin-like region) and 85-kDa nonstructural proteins are the precursors of the mature G2 and G1 proteins, respectively. The amino termini of the CCHF virus (Matin strain) G2 and G1 proteins were established by microsequencing to be equivalent to aa 525 and 1046, respectively, of the encoded polyprotein precursor. The tetrapeptides RRLL and RKPL are immediately upstream of the cleavage site for mature G2 and G1, respectively. These are completely conserved among the predicted polyprotein sequences of all the CCHF virus strains and closely resemble the tetrapeptides that represent the major cleavage recognition sites present in the glycoprotein precursors of arenaviruses, such as Lassa fever virus (RRLL) and Pichinde virus (RKLL). These results strongly suggest that CCHF viruses (and other members of the genus Nairovirus) likely utilize the subtilase SKI-1/S1P-like cellular proteases for the major glycoprotein precursor cleavage events, as has recently been demonstrated for the arenaviruses.

Animals↗
PubMed2003

Reverse genetics for crimean-congo hemorrhagic fever virus.

The widespread geographical distribution of Crimean-Congo hemorrhagic fever (CCHF) virus (more than 30 countries) and its ability to produce severe human disease with high mortality rates (up to 60%) make CCHF a major public health concern worldwide. We describe here the successful establishment of a reverse genetics technology for CCHF virus, a member of the genus Nairovirus, family BUNYAVIRIDAE: The RNA polymerase I (pol I) system was used to generate artificial viral RNA genome segments (minigenomes), which contained different reporter genes in antisense (virus RNA) or sense (virus-complementary RNA) orientation flanked by the noncoding regions of the CCHF virus S segment. Reporter gene expression was observed in different eukaryotic cell lines following transfection and subsequent superinfection with CCHF virus, confirming encapsidation, transcription, and replication of the pol I-derived minigenomes. The successful transfer of reporter gene activity to fresh cells demonstrated the generation of recombinant CCHF viruses, thereby confirming the packaging of the pol I-derived minigenomes into progeny viruses. The system offers a unique opportunity to study the biology of nairoviruses and to develop therapeutic and prophylactic measures against CCHF infections. In addition, we demonstrated for the first time that the human pol I system can be used to develop reverse genetics approaches for viruses in the family BUNYAVIRIDAE: This is important since it might facilitate the manipulation of bunyaviruses with cell and host tropisms restricted to primates.

Animals↗
PubMed2005

Rift Valley fever virus.

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.

Animals↗
PubMed2002

Nairobi sheep disease virus, an important tick-borne pathogen of sheep and goats in Africa, is also present in Asia.

Nairobi sheep disease (NSD) virus is the prototype of the tick-borne NSD serogroup, genus Nairovirus, family Bunyaviridae. It is highly pathogenic for sheep and goats, causes disease in humans, and is widespread throughout East Africa. Ganjam virus has caused disease in goats and humans in India. Due to their occurrence on different continents and association with different ticks, these viruses were considered distinct despite serologic cross-reactivity. Their S RNA genome segments and encoded nucleocapsid proteins were found to be 1590 nucleotides and 482 amino acids in length and differed by only 10 and 3% at nucleotide and amino acid levels, respectively. Genetic and serologic data demonstrate that Ganjam virus is an Asian variant of NSD virus. These viruses were phylogenetically more closely related to Hazara virus than Dugbe virus.

Africa↗