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At least 19 recordsLinked to original sources
PubMed1995

Transcription of a recombinant bunyavirus RNA template by transiently expressed bunyavirus proteins.

We describe a convenient system for analyzing bunyavirus transcription using a recombinant RNA template derived from the plasmid pBUNSCAT, which comprises a negative-sense reporter gene (chloramphenicol acetyltransferase or CAT) flanked by the exact 5' and 3' untranslated regions of the Bunyamwera virus (BUN) S RNA segment. When cells which expressed bunyavirus proteins (either by recombinant vaccinia viruses or by the vaccinia virus-T7 system) were transfected with BUNSCAT RNA, CAT activity could be measured, indicating transcription of the negative-sense reporter RNA into mRNA. The system permits investigation of both the protein and RNA sequence requirements for transcription. Extensions of 2 bases at the 5' end or 11 or 35 bases at the 3' end of BUNSCAT RNA allowed transcription but a lower level than the wild-type template. Deletion of the 5 nucleotides at the 3' end of BUNSCAT RNA reduced CAT activity by > 99%. Investigation of the viral protein requirements of the system showed that only the bunyavirus L and N proteins were needed for CAT activity. The BUN L protein was also able to transcribe the reporter RNA in concert with the N proteins of closely related bunyaviruses such as Batai, Cache Valley, Maguari, Main Drain, and Northway, but only inefficiently with those of Kairi, Guaroa, or Lumbo viruses. When BUN L proteins containing specific mutations were expressed CAT activity was only observed using those mutated L proteins previously reported to be active in a nucleocapsid transfection assay (H. Jin and R. M. Elliott, 1992, J. Gen. Virol. 73, 2235-2244). These results illustrate the utility of this system for a detailed genetic analysis of the factors involved in bunyavirus transcription.

Amino Acid Sequence↗
PubMed1981

Radioimmune assays and molecular studies that place Anopheles B and Turlock serogroup viruses in the Bunyavirus genus (Bunyaviridae).

Molecular analyses indicate that Turlock virus (TUR, Turlock serogroup) and Boraceia virus (BOR, Anopheles B serogroup) have virion RNA species and polypeptides comparable in size to those of members of the Bunyavirus genus and unlike those of members of the newly defined Phlebovirus, Nairovirus, or Uukuvirus genera (Bunyaviridae). The 11 terminal 3' end nucleotides of the three virion RNA species of both BOR and TUR viruses (HOUCAUCACAUG...) are identical in sequence to the 3' end sequences of the viral RNA species of snowshoe hare (SSH) and La Crosse bunyaviruses (LAC, California serogroup, Bunyavirus genus). Competition radioimmune assays (RIA), using iodinated LAC nucleocapsid polypeptide (N), or LAC glycoproteins (G1, G2), and LAC rabbit hyperimmune antisera, or iodinated Oriboca (ORI, Group C, Bunyavirus genus) N, or G1 and G2 polypeptides and LAC antisera, or iodinated Bunyamwera (BUN, Bunyamwera serogroup, Bunyavirus genus) N, or G1 and G2 polypeptides and BUN or LAC antisera, have indicated that the virion polypeptides of BOR virus share antigenic determinants with these other bunyaviruses. Competition RIA analyses also have shown that TUR virus shares antigenic determinants with LAC virus. The competition RIA analyses have confirmed the antigenic relationships of LAC, SSH, trivittatus, Bwamba, Aino, Simbu, Mermet, Guaroa, Lumbo, Tahyna, ORI, Anopheles A, BUN, Capim, Guama and Shark river viruses (Bunyavirus genus members), and lack of antigenic relationships between Karimabad, or Chagres, or sandfly fever, Sicilian, Viruses (Phlebovirus genus members), and the bunyaviruses, LAC, ORI, or BUN.

Animals↗
PubMed1988

Bunyavirus-vector interactions.

Recent advances in the genetics and molecular biology of bunyaviruses have been applied to understanding bunyavirus-vector interactions. Such approaches have revealed which virus gene and gene products are important in establishing infections in vectors and in transmission of viruses. However, much more information is required to understand the molecular mechanisms of persistent infections of vectors which are lifelong but apparently exert no untoward effect. In fact, it seems remarkable that LAC viral antigen can be detected in almost every cell in an ovarian follicle, yet no untoward effect on fecundity and no teratology is seen. Similarly the lifelong infection of the vector would seem to provide ample opportunity for bunyavirus evolution by genetic drift and, under the appropriate circumstances, by segment reassortment. The potential for bunyavirus evolution by segment reassortment in vectors certainly exists. For example the Group C viruses in a small forest in Brazil seem to constitute a gene pool, with the 6 viruses related alternately by HI/NT and CF reactions, which assay respectively M RNA and S RNA gene products (Casals and Whitman, 1960; Shope and Causey, 1962). Direct evidence for naturally occurring reassortant bunyaviruses has also been obtained. Oligonucleotide fingerprint analyses of field isolates of LAC virus and members of the Patois serogroup of bunyaviruses have demonstrated that reassortment does occur in nature (El Said et al., 1979; Klimas et al., 1981; Ushijima et al., 1981). Determination of the genotypic frequencies of viruses selected by the biological interactions of viruses and vectors after dual infection and segment reassortment is an important issue. Should a virus result that efficiently interacts with alternate vector species, the virus could be expressed in different circumstances with serious epidemiologic consequences. Dual infection of vectors with different viruses is not unlikely, because many bunyaviruses are sympatric in nature. For example, the Ae. trivittatus-cottontail rabbit and the Ae. triseriatus-squirrel arbovirus cycles are sympatric in the ecotone between their respective grassland and forest ecosystems (LeDuc, 1979). Should a LaCrosse virus variant or reassortant evolve that was efficiently vectored by Ae. trivittatus mosquitoes, significantly more human infections with La Crosse virus would likely occur. Unlike Ae. triseriatus, Ae. trivittatus mosquitoes are not restricted to forested areas and consequently are more likely to encounter and to feed upon humans.(ABSTRACT TRUNCATED AT 400 WORDS)

Aedes↗
PubMed1995

Determination and comparative analysis of the small RNA genomic sequences of California encephalitis, Jamestown Canyon, Jerry Slough, Melao, Keystone and Trivittatus viruses (Bunyaviridae, genus Bunyavirus, California serogroup).

The nucleotide sequences of the small (S) genomic RNAs of six California (CAL) serogroup bunyaviruses (Bunyaviridae: genus Bunyavirus) were determined. The S RNAs of two California encephalitis virus strains, two Jamestown Canyon virus strains, Jerry Slough virus, Melao virus, Keystone virus and Trivittatus virus contained the overlapping nucleocapsid (N) and non-structural (NSs) protein open reading frames (ORFs) as described previously for the S RNAs of other CAL serogroup viruses. All N protein ORFs were 708 nucleotides in length and encoded a putative 235 amino acid gene product. The NSs ORFs were found to be of two lengths, 279 and 294 nucleotides, which potentially encode 92 and 97 amino acid proteins, respectively. The complementary termini and a purine-rich sequence in the 3' non-coding region (genome-complementary sense) were highly conserved amongst CAL serogroup bunyavirus S RNAs. Phylogenetic analyses of N ORF sequences indicate that the CAL serogroup bunyaviruses can be divided into three monophyletic lineages corresponding to three of the complexes previously derived by serological classification. The truncated version of the NSs protein, which is found in five CAL serogroup bunyaviruses, appears to have arisen twice during virus evolution.

Amino Acid Sequence↗
PubMed2025

An Introduction to the Bunyaviruses.

The bunyaviruses are an ever-expanding group of RNA viruses that have been linked to a variety of different diseases around the world. First characterized nearly a century ago, over 500 different types of bunyaviruses have been characterized thus far, with hosts ranging from mammals to plants to single-celled organisms. As many of the currently described bunyaviruses have been found to be vector-borne, with transmission being mediated by either insects or rodents, these viruses have incorporated immune-evasive molecules into their relatively small genome. As these viruses have been implicated in a number of public health threats, there is an increased interest in performing experiments that could improve our understanding of these infectious agents. Therefore, the objectives of this book are outlined in this chapter, with a variety of techniques being described for the study of a variety of different bunyaviruses.

Animals↗
PubMedDate not supplied

Identification of Simbu, California and Bunyamwera serogroup bunyaviruses by nested RT-PCR.

We describe a reverse transcription-polymerase chain reaction (RT-PCR) with primers that anneal to the 5' and 3' ends and amplify the Bunyavirus S RNA segments. The RT-PCR was done on the fluids of C6/36 cells infected with each of 21 bunyaviruses. The bunyaviruses studied, with the exception of Catu virus, produced amplicons having 700 to 1300 base pairs and probably contained the whole S RNA segment sequence. A nested PCR performed with these amplicons distinguished California and most Bunyamwera serogroup viruses from other bunyaviruses by use of BBC specific internal primers for the S RNA segment, and distinguished Simbu serogroup viruses from others by use of BS specific internal primers. The nested-PCR amplicons of Guaroa, Maguari, California encephalitis, Bunyamwera, and Oropouche viruses were sequenced. The sequences were aligned with previously known sequences of the S RNA segment of the same viruses, showing a high degree of homology and thus confirming the specific origin of these amplicons. The nested RT-PCR is suitable as a specific screening for most California and Bunyamwera serogroup and Simbu serogroup viruses depending on the use of BBC or BS internal primers. Oropouche virus is an important public health problem in Brazil and the nested PCR with BS primers could be used for the detection of this virus in tissue culture and mouse brain isolates as well as in clinical samples.

Base Sequence↗
PubMed1977

The virus particle nucleic acids and proteins of four bunyaviruses.

The structural polypeptides of five bunyaviruses, snowshoe hare, Lumbo and La Crosse viruses (members of the California encephalitis subgroup of bunyaviruses), Bunyamwera and Main Drain viruses (members of the Bunyamwera subgroup of bunyaviruses), have been compared by polyacrylamide-SDS gel electrophoresis. Each virus was found to possess three major structural polypeptides, two glycoproteins (G1 and G2), and one nucleocapsid protein (N). Although the sizes of the G1 polypeptides (mol. wt. approx. 115 X 10(3)) and G2 polypeptides (mol. wt. approx. 38 X 10(3)) of the five viruses were found to be essentially similar, the sizes of the N polypeptides of the various viruses differed (mol. wt. range 19 to 24 X 10(3)). The RNA genomes of four bunyaviruses (snowshoe hare, La Crosse, Bunyamwera and Main Drain) have also been compared. Each virus has three RNA species of mol. wt. approx. 3 X 10(6), 1-9 X 10(6) and 0-4 X 10(6). Minor size differences were observed for the smallest RNA species of the four viruses (mol. wt. range 0-34 to 0-50 X 10(6)). For snowshoe hare virus the RNA segments hav a 5' sequence of pppAp...which suggests that the RNA is linear and not circular.

Arboviruses↗
PubMed1980

Characterization of the viral ribonucleic acids and structural polypeptides of Anopheles A, Bunyamwera, Group C, California, Capim, Guama, Patois, and Simbu bunyaviruses.

Analyses of the viral ribonucleic acids and structural polypeptides of 17-22 of the 119 accepted or proposed members of the Bunyavirus genus of arboviruses (family Bunyaviridae), have shown that from the standpoint of their structural components these viruses are highly comparable to each other. The average molecular weights for the three viral RNA species (L, large, M, medium, S, small) of 17 bunyaviruses were 2.93 X 10(6) (L, range 2.7-3.1 X 10(6)), 2.0 X 10(6) (M, range 1.8-2.3 X 10(6)), and 0.435 X 10(6) (Sm range 0.28-0.50 X 10(6)). The average molecular weights of the three major virion polypeptides (glycoproteins G1 and G2, and nucleocapsid protein, N) of 22 bunyaviruses were 115 X 10(3) (G1, range 108-120 X 10(3)), 37 X 10(3) (G2, range 20-41 X 10(3)) and 22 X 10(3) (N, range 19-25 X 10(3)). These results indicate that the structural components of bunyaviruses are different from those reported for Phlebotomus fever, Uukuniemi, and Crimean-Congo hemorrhagic fever, and other members of the Bunyaviridae family that are not currently assigned to a genus.

Animals↗
PubMed1991

Arthropod vectors in the evolution of bunyaviruses.

Viruses from each genus of Bunyaviridae have preferential relationships to the arthropods of only one or two families, i.e. Bunyavirus to mosquitoes (Culicidae), Phlebovirus to sand flies (Psychodidae) and mosquitoes, Uukuvirus and Nairovirus to ticks (Ixodidae and Argasidae). An exception is genus Hantavirus not proven to be transmitted by vectors. Within the Bunyavirus genus 16 serogroups have been recognized on the basis of their antigenic relationship. Based on isolations from the nature each serogroup is preferentially linked with arthropod species (mostly mosquitoes) of one, or two genera. For 8 out of 16 serogroups Culex mosquitoes are the main insect vectors. Two serogroups are linked with Aedes mosquitoes, three with Anopheles mosquitoes. Aedeomyia mosquitoes, Culicoides bitting miges and Hyalomma ticks are vectors of one serogroup each. Evolutionary trends within the genus Bunyavirus and within the family Bunyaviridae can be recognized based on relationships of bunyaviruses to their arthropod vectors.

Animals↗
PubMed1995

Tropism of bunyaviruses: evidence for a G1 glycoprotein-mediated entry pathway common to the California serogroup.

The California serogroup is composed of antigenically and biologically related viruses within the Bunyavirus genus of the Bunyaviridae. We used a large panel of murine cells to study their tissue tropisms and found virtually identical patterns of viral replication among all of the members of this serogroup, in contrast to other members of the family (Bunyamwera, Cache Valley, and Punta Toro viruses). By analyzing the nonpermissive infections with both an RNA dot-blot and a virus binding assay, we determined that tropism for cultured cells was determined at the level of entry. A truncated soluble form of the La Crosse G1 glycoprotein (sG1) was expressed in a baculovirus system and, despite slight differences in glycosylation, was shown to resemble native G1 by immunoprecipitation with six monoclonal antibodies. sG1 bound to permissive but not to nonpermissive cell lines, as demonstrated by flow cytometry. The sG1 effectively blocked infection of permissive cell lines with all of the California serogroup viruses, but did not block infection of two other bunyaviruses. These results indicate that the California serogroup bunyaviruses share a common receptor on vertebrate cells which may differ from the receptor used by other Bunyaviridae and demonstrate that the G1 glycoprotein is the virus attachment protein. sG1 will be a useful reagent in the search for a putative receptor molecule.

3T3 Cells↗
PubMed1988

Molecular and biochemical studies of the evolution, infection and transmission of insect bunyaviruses.

Members of the Bunyaviridae family of RNA viruses (bunyaviruses, hantaviruses, nairoviruses, phleboviruses and uukuviruses) have been studied at the molecular and genetic level to understand the basis of their evolution and infection in vertebrate and invertebrate (arthropod) hosts. With the exception of the hantaviruses, these viruses infect and are transmitted by a variety of blood-sucking arthropods (mosquitoes, phlebotomines, gnats, ticks, etc.). The viruses are responsible for infection of various vertebrate species, occasionally causing human disease, morbidity and mortality (e.g. Rift Valley fever, Crimean-Congo haemorrhagic fever, Korean haemorrhagic fever). Genetic and molecular analyses of bunyaviruses have established the coding assignments of the three viral RNA species and documented which viral gene products determine host range and virulence. Ecological studies, with molecular techniques, have provided evidence for bunyavirus evolution in nature through genetic drift (involving the accumulation of point mutations) and shift (RNA-segment reassortment).

Animals↗
PubMed1982

The 3' terminal RNA sequences of bunyaviruses and nairoviruses (Bunyaviridae): evidence of end sequence generic differences within the virus family.

The 3' terminal nucleotide sequences of the three virus RNA species of viruses representing eight serogroups of bunyaviruses (genus Bunyavirus, Bunyaviridae) and six serogroups of nairoviruses (genus Nairovirus, Bunyaviridae) have been characterized. Members of the Bunyavirus genus have conserved 3' end sequences (generally, 3' UCAUCACAUGA...) that differ from the conserved 3' end sequences of members of the Nairovirus genus (generally, 3' AGAGUUUCU...).

Base Sequence↗
PubMed1988

Biochemical and serological comparisons of Australian bunyaviruses belonging to the Simbu serogroup.

Comparative analysis of the structural and possible non-structural proteins of seven Simbu serogroup bunyaviruses isolated in Australia revealed them all to be similar in size to those of Bunyamwera virus, the prototype of the Bunyavirus genus. The molecular weights of the structural proteins for these bunyaviruses (Akabane, Aino, Tinaroo, Douglas, Peaton, Facey's Paddock and Thimiri viruses) were 193K to 205K (L), 103K to 125K (G1), 33K to 37K (G2) and 25K to 26K (N). Analysis of the virion RNA of three viruses (Akabane, Douglas and Facey's Paddock) showed them all to be similar to Bunyamwera virus RNA, apparent Mr values being 2.6 X 10(6) (L), 1.4 X 10(6) to 1.9 X 10(6) (M) and 0.24 X 10(6) to 0.42 X 10(6) (S). Host cell protein synthesis was switched off late during infection, revealing four structural proteins L, G1, G2 and N. Comparative analysis of these protein profiles in infected Vero cells showed each virus, although similar, to be unique and easily identified; this method of comparison was efficient and rapid compared to the difficulty in obtaining adequate amounts of purified virus for analysis. Additionally, for all viruses except Douglas, two to four possible non-structural proteins were identified, with an Mr range from 12K to 30K. The viruses Akabane and Tinaroo, which have previously been shown to cross-react by plaque inhibition virus neutralization tests, were readily distinguished in migration of the G1 glycoprotein and by analysis of plaque reduction virus neutralization data using linear regression analysis of the dose-response curves. Using these same analyses, the differences between Aino and Douglas viruses, also related by plaque inhibition, were even greater. Application of the biochemical analysis of virus-specified proteins and some serological comparisons identified a mixed pool of different viruses in two unknown isolates grouped as Simbu serogroup viruses, and further identified a potential teratogenic strain in one of the two pools.

Animals↗
PubMed1994

The S RNA genome segments of Batai, Cache Valley, Guaroa, Kairi, Lumbo, Main Drain and Northway bunyaviruses: sequence determination and analysis.

Bunyaviruses have a genome comprising three segments of negative-sense RNA. The smallest RNA segment, S, encodes the nucleocapsid protein, N, and a nonstructural protein, NSs, in overlapping reading frames. The sequences of the S genome RNA segments of seven bunyaviruses (Batai, Cache Valley, Guaroa, Kairi, Main Drain, Northway and Lumbo) were determined from cloned cDNAs obtained using a one-step reverse transcription-PCR protocol. These sequences were compared to those of six viruses previously published, reinforcing earlier conclusions about relationships of the bunyaviruses. Sequence homologies between N proteins correlated with the subdivision of these viruses into three serogroups, Bunyamwera, California and Simbu. The encoded N proteins are either 233 or 235 amino acids in length, depending on the serogroup, whereas the NSs proteins are more variable (83 to 109 amino acids). Certain nucleotide sequence motifs are conserved in the S segments of the Bunyamwera and California serogroup viruses, including the spacing of the AUG initiation codons for the N and NSs proteins (except Guaroa virus), and a CA-rich motif in the virion-sense RNA just downstream of the predicted mRNA termination site. A duplicated sequence was observed in the 3' non-coding region of the Lumbo virus S segment, which accounts for the significantly longer S genome segment of this virus.

Amino Acid Sequence↗
PubMed1997

Sequence determination and phylogenetic analysis of the Akabane bunyavirus S RNA genome segment.

The nucleotide sequence of the small (S) RNA segment of Akabane (AKA) bunyavirus was determined. The segment is 858 nucleotides long and contains two overlapping open reading frames (ORFs), which encode the nucleocapsid (N) and nonstructural (NSs) proteins, consistent with other bunyaviruses. Comparisons with the Aino virus S RNA sequence indicated that there is 73.5% identity in nucleotide sequence. However, the sequence identity of the 5' non-coding region of the genomic RNA between these two viruses is only 55%. The N ORFs from 20 Japanese and 2 Australian isolates of AKA virus were sequenced and subjected to phylogenetic analysis. This suggested that AKA virus has evolved in multiple lineages. Twenty-three isolates were grouped into three major clusters, and the cluster which includes recent isolates was subdivided into two branches. Thus, phylogenetic analysis of the AKA virus N protein gene gives a greater insight into bunyavirus evolution.

Genome, Viral↗
PubMed1982

Mutant identifying a third recombination group in a bunyavirus.

Only two recombination groups have been reported in genetic analyses of ts mutants of 10 different bunyaviruses from the Bunyamwera and California encephalitis serogroups, although three groups are expected from the tripartite structure of the genome of all members of the family Bunyaviridae. We describe now a ts mutant of Maguari virus, MAGts23(III), which recombined in both vertebrate (BHK-21) and invertebrate (Aedes albopictus) cells with mutants representing recombination groups I and II of this Bunyamwera serogroup virus. In addition, MAGts23(III) recombined with two mutants MAGts20 and MAGts21, provisionally identified as double mutants by their failure to recombine with group I or group II mutants, Mutant MAGts23(III) therefore represents a third bunyavirus recombination group. Mutant MAGts23(III) differed phenotypically from other bunyavirus mutants by growth restriction in BS-C-1 cells. Wild-type recombinants were obtained in the heterologous cross of MAGts23(III) and a group II mutant of Bunyamwera virus, but not in a cross with a group I mutant. The recombinants had the G protein of the Maguari virus parent and the N protein of the Bunyamwera virus parent. Analysis of the phenotypes of clones isolated at permissive temperature from the progeny of the other cross [MAGts23(III) and a group I mutant of Bunyamwera virus] indicated that recombination occurred in this cross, but that the possible recombinant phenotypes were not recovered with equal frequency. As a consequence, it has not been possible to obtain a gene assignment for group III from genetic data alone.

Bunyamwera virus↗
PubMedDate not supplied

Bunyaviruses and Bunyaviridae.

A new family is described, the Bunyaviridae, which contains a single genus, Bunyavirus. The main characteristics of the family are as follows: single-stranded RNA, total molecular weight about 7 X 10(6) daltons, probably in three segments. Virions spherical, enveloped particles 90-100 nm in diameter. Envelope contains at least one virus-specified glycopeptide. Develop in the cytoplasm, mature by budding into smooth-surfaced vesicles in the Golgi region or nearby. Internal ribonucleoprotein composed of long strands 2-2.5 nm broad. There are at least 150 members, 87 serologically related bunyaviruses and other probable bunyaviruses.

Arboviruses↗