Drosophila X virus

Last updated
Drosophila X virus
Virus classification Red Pencil Icon.png
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: incertae sedis
Family: Birnaviridae
Genus: Entomobirnavirus
Species:
Drosophila X virus

Drosophila X virus (DXV) belongs to the Birnaviridae family of viruses. Birnaviridae currently consists of three genera. The first genus is Entomobirnavirus, which contains DXV. [1] The next genus is Aquabirnavirus, containing infectious pancreatic necrosis virus (IPNV). [1] The last genus is Avibirnavirus, which contains infectious bursal disease virus (IBDV). [1] All of these genera contain homology in three specific areas of their transcripts. The homology comes from the amino and carboxyl regions of preVP2, a small 21-residue-long domain near the carboxyl terminal of VP3, and similar small ORFs sequences. [1]

Contents

DXV was named after Drosophila melanogaster , where it was first isolated. DXV was first isolated and named in 1978. [2] DXV was discovered as a contaminant in adult D. melanogaster while studying rhabdoviruses. [2] Assay results of DXV showed that DXV induces sensitivity to both carbon dioxide and NH2, which suggests general anoxia. Therefore, the pathogenic pathway for DXV leads to anoxia sensitivity and death of D. melanogaster. [2] By negative contrast electron microscopy the DXV components were first visualized. [2] The origin of DXV is unknown and unclear. It was thought that DXV could have been pre-existent in Drosophila broods in a non-pathogenic form. Additionally, it was speculated that DXV might have originated as a contaminant from fetal calf serum in infection type studies because it was documented that endogenous bovine viruses were already in fetal calf serum. [3]

Structure, genome, and replication

Drosophila X virus genome has two segments: segment A & segment B. DXV genome.jpg
Drosophila X virus genome has two segments: segment A & segment B.

DXV is a Baltimore Class III naked (non-enveloped) virus. The capsid of this protein contains an icosahedral geometry (T=13) consisting of 260 trimeric VP2 capsomeres. Specifically, DXV contains a bi-segmented dsRNA genome. [1] Both segments of the DXV genome contain 5’ terminal GGA triplet and a 3’ terminal CCC triplet consensus, which is consistent with birnaviridae (Shwed, 2002). The segment A genome is 3360-bp in length. [1] Segment A encodes a polyprotein sequence as follows: NH2-preVP2-VP4-VP3-COOH. This segment contains a large and small ORF. The segment B genome is 2991-bp in length. [1] Segment B encodes a polypeptide sequence as follows: NH2-VP1-COOH. [4] The 5’ UTR of segment B is homologous to segment A, but unlike segment A, there is only one ORF. [4] Unusually, VP1 can be in two forms; as a free RdRp and as the genome-liked protein (VpG) that attaches to both 5’ end segments of the DXV through a Ser-5’-GMP phosphodiester bond. [5] The replication of DXV follows the characterized dsRNA virus replication cycle. [6]

The large ORF of segment A consists of 3069 nucleotides. [1] The UTRs are characterized as 107-bp on 5’ side and 157-bp on 3’ end. [1] The start codons can be at either position 102, or two codons downstream at position 108. However, the initiation codon starts at the 108-bp. [1] The translation of the large ORF transcript produces a 114-kDa polyprotein. [1] The mature VP4 protein, viral protease, assists this process to increase the processing of the polyprotein to generate preVP2 capsid protein, VP3 viral ribonucleoprotein (RNP), and additional VP4 proteins. [1] In addition VP3 proteins can associate with pre-VP2 as a structural protein [7] and with VP1 to function as a transcriptional activator. [8]

The small ORF of segment A consists of 711 nucleotides. [1] This ORF is in a location that extends across VP4/VP3 junction, although the precise position is unknown. [1] The mechanism for transcribing the small ORF is unknown. However, the possibility of ribosomal frameshifting has been ruled out since the small ORF site does not contain the characteristic hallmarks, such the 7 nucleotide long “slippery sequence” or downstream pseudoknot that is seen in other members of Birnaviridae. It is hypothesized the small ORF is translated in a mechanism that uses subgenomic transcripts. [1] In any case, the translation of the small ORF transcript produces a 27-kDa polypeptide. [1] This polypeptide consists of 28 of basic, mainly arginine, residues. However this polypeptide has not been detected in infected cells.[ citation needed ]

The segment B transcript encodes it encodes a 112.8-kDa VP1 polypeptide once translated. [4] This polypeptide has been characterized to be the RNA-dependent RNA polymerase (RdRp) and the VpG. [5] This polypeptide is 977 amino acids in length, making it the largest encoded RdRp in the Birnaviridae family. [4] The RdRp contains a consensus GTP-binding site and is thought to contain self-guanylylation activity, making it consistent with the Birnaviridae RdRp capacity. [4]

Tropism

Currently, DXV does not infect vertebrates. It is known that invertebrates, such as insects, are hosts for DXV, but their specific tissue tropism is not known for certain. [9] Tracheal cells were thought to be a possible target because there is evidence that Drosophila flies that are infected by DXV suffered from lack of oxygen supply to their tissues, which eventually leads to death. [2] Based on previous studies, DXV was unsuccessfully cultured in vertebrate cells lines and mouse brain.[ citation needed ]

Genetic variability

It has not been shown yet that DXV naturally infects Drosophila flies therefore; there are no wild-type strains of DXV. The Culex Y virus (CYV) is a tentative member of the genus that DXV is in. It has been proposed that CYV could act as a wild-type counterpart in studies that rely on DXV. [10] In addition, the Espirito Santo virus (ESV) is defined as a sister species to DXV. This particular virus, ESV, was observed in an Aedes albopictus cell culture, which was obtained from a patient's serum infected with DENV-2. A difference between the ESV and CYV would be CYV's ability to independently replicate without on other viruses in insect cell culture. [11] A non-AUG start codon in ORF5 has been shown in Drosophila and may regulate translation, which indicates its function in entomobirnavirus host in reactions. [11] When ORF5 is expressed, it is thought to mediate ribosomal frameshifting. [11] A heptanucleotide that is located upstream of ORF (1897UUUUUUA) is found in both ESV and DXV. Together with phylogenetic analysis and the location differences of nucleotide and amino acids between CYV and ESV, it has been shown that CYV and ESV is one sister species to DXV. [11]

Research

Although widely used in the laboratory, DXV has never been found as a natural infection of Drosophila, and was originally identified in laboratory cell culture. DXV can infect fruit flies of the genus Drosophila and is commonly used to study innate immunity in the common model organism Drosophila melanogaster . The virus is also often used to study RNA interference as a mechanism of viral immunity in Drosophila.[ citation needed ]

DXV was a contaminant that was isolated in infectious studies with a member of the Rhabdoviridae family, the Sigma virus. [9] Since then, DXV has been widely used in research and has significantly contributed to the current knowledge of insect specific immune system. [12] Infection studies with DXV has shed light on the innate immune response and RNA interference (RNAi) in Drosophila flies. [12] Additionally, using DXV in Drosophila showed that RNAi is a major form of an antiviral effector mechanism. [11] In regards to the Toll pathway in antiviral response, there is evidence to show this pathway inhibits DXV replication in Drosophila. [13] Furthermore, findings from DXV research on Drosophila significantly influenced studies on the dengue virus (DENV) to learn more about its innate immune response toward infections. [11] It has been shown that DENV is controlled by RNAi in Drosophila cells and studies revealed that DENV's interaction with RNAi are just as vital as siRNAs. Engineered transgenic Aedes aegypti mosquitos were shown to have resistance (caused by an RNAi response) against DENV-2 infections. [14]

Related Research Articles

<span class="mw-page-title-main">Poliovirus</span> Enterovirus

A poliovirus, the causative agent of polio, is a serotype of the species Enterovirus C, in the family of Picornaviridae. There are three poliovirus serotypes: types 1, 2, and 3.

<i>Hepadnaviridae</i> Family of viruses

Hepadnaviridae is a family of viruses. Humans, apes, and birds serve as natural hosts. There are currently 18 species in this family, divided among 5 genera. Its best-known member is hepatitis B virus. Diseases associated with this family include: liver infections, such as hepatitis, hepatocellular carcinomas, and cirrhosis. It is the sole accepted family in the order Blubervirales.

<span class="mw-page-title-main">Picornavirus</span> Family of viruses

Picornaviruses are a group of related nonenveloped RNA viruses which infect vertebrates including fish, mammals, and birds. They are viruses that represent a large family of small, positive-sense, single-stranded RNA viruses with a 30 nm icosahedral capsid. The viruses in this family can cause a range of diseases including the common cold, poliomyelitis, meningitis, hepatitis, and paralysis.

<i>Wolbachia</i> Genus of bacteria in the Alphaproteobacteria class

Wolbachia is a genus of intracellular bacteria that infects mainly arthropod species, including a high proportion of insects, and also some nematodes. It is one of the most common parasitic microbes, and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host species cannot reproduce, or even survive, without Wolbachia colonisation. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70% of all insect species are estimated to be potential hosts.

<i>Dengue virus</i> Species of virus

Dengue virus (DENV) is the cause of dengue fever. It is a mosquito-borne, single positive-stranded RNA virus of the family Flaviviridae; genus Flavivirus. Four serotypes of the virus have been found, a reported fifth has yet to be confirmed, all of which can cause the full spectrum of disease. Nevertheless, scientists' understanding of dengue virus may be simplistic as, rather than distinct antigenic groups, a continuum appears to exist. This same study identified 47 strains of dengue virus. Additionally, coinfection with and lack of rapid tests for zika virus and chikungunya complicate matters in real-world infections.

<i>Birnaviridae</i> Family of viruses

Birnaviridae is a family of double-stranded RNA viruses. Salmonid fish, birds and insects serve as natural hosts. There are currently 11 species in this family, divided among seven genera. Diseases associated with this family include infectious pancreatic necrosis in salmonid fish, which causes significant losses to the aquaculture industry, with chronic infection in adult salmonid fish and acute viral disease in young salmonid fish.

<span class="mw-page-title-main">Adeno-associated virus</span> Species of virus

Adeno-associated viruses (AAV) are small viruses that infect humans and some other primate species. They belong to the genus Dependoparvovirus, which in turn belongs to the family Parvoviridae. They are small replication-defective, nonenveloped viruses and have linear single-stranded DNA (ssDNA) genome of approximately 4.8 kilobases (kb).

<i>Orbivirus</i> Genus of viruses

Orbivirus is a genus of double-stranded RNA viruses in the family Reoviridae and subfamily Sedoreovirinae. Unlike other reoviruses, orbiviruses are arboviruses. They can infect and replicate within a wide range of arthropod and vertebrate hosts. Orbiviruses are named after their characteristic doughnut-shaped capsomers.

HHV Latency Associated Transcript is a length of RNA which accumulates in cells hosting long-term, or latent, Human Herpes Virus (HHV) infections. The LAT RNA is produced by genetic transcription from a certain region of the viral DNA. LAT regulates the viral genome and interferes with the normal activities of the infected host cell.

Group-specific antigen, or gag, is the polyprotein that contains the core structural proteins of an Ortervirus. It was named as such because scientists used to believe it was antigenic. Now it is known that it makes up the inner shell, not the envelope exposed outside. It makes up all the structural units of viral conformation and provides supportive framework for mature virion.

Drosophila C virus belongs to the genus Cripavirus and was previously thought to be a member of the virus family Picornaviridae; it has since been classified as belonging to the Dicistroviridae. It is a single stranded positive sense RNA virus of approximately 9300 nucleotides and it contains two open reading frames. The virus particles are 30 nm in diameter and are made up of approximately 30% of RNA and 70% protein. The virus capsid is composed of three major polypeptides and two minor polypeptides.

<span class="mw-page-title-main">Double-stranded RNA viruses</span> Type of virus according to Baltimore classification

Double-stranded RNA viruses are a polyphyletic group of viruses that have double-stranded genomes made of ribonucleic acid. The double-stranded genome is used to transcribe a positive-strand RNA by the viral RNA-dependent RNA polymerase (RdRp). The positive-strand RNA may be used as messenger RNA (mRNA) which can be translated into viral proteins by the host cell's ribosomes. The positive-strand RNA can also be replicated by the RdRp to create a new double-stranded viral genome.

<span class="mw-page-title-main">Reverse genetics</span> Method in molecular genetics

Reverse genetics is a method in molecular genetics that is used to help understand the function(s) of a gene by analysing the phenotypic effects caused by genetically engineering specific nucleic acid sequences within the gene. The process proceeds in the opposite direction to forward genetic screens of classical genetics. While forward genetics seeks to find the genetic basis of a phenotype or trait, reverse genetics seeks to find what phenotypes are controlled by particular genetic sequences.

Batai orthobunyavirus (BATV) is a RNA virus belonging to order Bunyavirales, genus Orthobunyavirus.

<i>Avibirnavirus</i> Genus of viruses

Avibirnavirus is a genus of viruses in family Birnaviridae. There is a single species in this genus: Infectious bursal disease virus, which infects chickens and other fowl. It causes severe inflammation of the bursa of Fabricius, and causes considerable morbidity and mortality.

Entomobirnavirus is a genus of viruses in the family Birnaviridae. Its natural host is the fly Drosophila melanogaster. There are two species in this genus.

<i>Eilat virus</i> Species of virus

Eilat virus (EILV) is a unique Alphavirus which is known mainly for its host range restriction generally to insects by means of RNA replication. The virus is found in the Negev desert. It is incapable of infecting vertebrate cells, differentiating it from other alphaviruses.

Flock House virus (FHV) is in the alphanodavirus genus of the Nodaviridae family of viruses. Flock House virus was isolated from a grass grub at the Flock House research station in Bulls, New Zealand. FHV is an extensively studied virus and is considered a model system for the study of other non-enveloped RNA viruses owing to its small size and genetic tractability, particularly to study the role of the transiently exposed hydrophobic gamma peptide and the metastability of the viral capsid. FHV can be engineered in insect cell culture allowing for the tailored production of native or mutant authentic virions or virus-like-particles. FHV is a platform for nanotechnology and nanomedicine, for example, for epitope display and vaccine development. Viral entry into host cells occurs via receptor-mediated endocytosis. Receptor binding initiates a sequence of events during which the virus exploits the host environment in order to deliver the viral cargo in to the host cytosol. Receptor binding prompts the meta-stability of the capsid–proteins, the coordinated rearrangements of which are crucial for subsequent steps in the infection pathway. In addition, the transient exposure of a covalently-independent hydrophobic γ-peptide is responsible for breaching cellular membranes and is thus essential for the viral entry of FHV into host cells.

Jingmenvirus is a group of positive-sense single-stranded RNA viruses with segmented genomes. They are primarily associated with arthropods and are one of only two known segmented RNA viruses that infect animal hosts. The first member of the group, the Jingmen tick virus (JMTV), was described in 2014. Another member, the Guaico Culex virus (GCXV), has a highly unusual multicomponent architecture in which the genome segments are separately enclosed in different viral capsids.

<i>Astroviridae</i> Family of viruses

Astroviridae is a family of non-enveloped ssRNA viruses that cause infections in different animals. The family name is derived from the Greek word astron ("star") referring to the star-like appearance of spikes projecting from the surface of these small unenveloped viruses. Astroviruses were initially identified in humans but have since been isolated from other mammals and birds. This family of viruses consists of two genera, Avastrovirus (AAstV) and Mamastrovirus (MAstV). Astroviruses most frequently cause infection of the gastrointestinal tract but in some animals they may result in encephalitis, hepatitis (avian) and nephritis (avian).

References

  1. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 Chung, H. K.; Kordyban, S; Cameron, L; Dobos, P (1996). "Sequence analysis of the bicistronic Drosophila X virus genome segment a and its encoded polypeptides". Virology. 225 (2): 359–68. doi: 10.1006/viro.1996.0610 . PMID   8918922.
  2. 1 2 3 4 5 Teninges, D.; Ohanessian, A.; Richard-Molard, C.; Contamine, D. (1979). "Isolation and Biological Properties of Drosophila X Virus". Journal of General Virology. 42 (2): 241–254. doi: 10.1099/0022-1317-42-2-241 .
  3. ↑ Igarashi, A; Koo, R; Stollar, V (1977). "Evolution and properties of Aedes albopictus cell cultures persistently infected with sindbis virus". Virology. 82 (1): 69–83. doi:10.1016/0042-6822(77)90033-2. PMID   898680.
  4. 1 2 3 4 5 Shwed, P. S.; Dobos, P; Cameron, L. A.; Vakharia, V. N.; Duncan, R (2002). "Birnavirus VP1 proteins form a distinct subgroup of RNA-dependent RNA polymerases lacking a GDD motif". Virology. 296 (2): 241–50. doi: 10.1006/viro.2001.1334 . PMID   12069523.
  5. 1 2 Calvert, J. G.; Nagy, E; Soler, M; Dobos, P (1991). "Characterization of the VPg-dsRNA linkage of infectious pancreatic necrosis virus". The Journal of General Virology. 72 (10): 2563–7. doi: 10.1099/0022-1317-72-10-2563 . PMID   1919532.
  6. ↑ Bernard, J (1980). "Drosophila X virus RNA polymerase: Tentative model for in vitro replication of the double-stranded virion RNA". Journal of Virology. 33 (2): 717–23. doi:10.1128/JVI.33.2.717-723.1980. PMC   288596 . PMID   6774107.
  7. ↑ Saugar, I; Irigoyen, N; Luque, D; Carrascosa, J. L.; Rodríguez, J. F.; Castón, J. R. (2010). "Electrostatic interactions between capsid and scaffolding proteins mediate the structural polymorphism of a double-stranded RNA virus". Journal of Biological Chemistry. 285 (6): 3643–50. doi: 10.1074/jbc.M109.075994 . PMC   2823505 . PMID   19933276.
  8. ↑ Garriga, D; Navarro, A; Querol-Audí, J; Abaitua, F; Rodríguez, J. F.; Verdaguer, N (2007). "Activation mechanism of a noncanonical RNA-dependent RNA polymerase". Proceedings of the National Academy of Sciences. 104 (51): 20540–5. Bibcode:2007PNAS..10420540G. doi: 10.1073/pnas.0704447104 . PMC   2154467 . PMID   18077388.
  9. 1 2 Tsai, C. W.; McGraw, E. A.; Ammar, E. -D.; Dietzgen, R. G.; Hogenhout, S. A. (2008). "Drosophila melanogaster Mounts a Unique Immune Response to the Rhabdovirus Sigma virus". Applied and Environmental Microbiology. 74 (10): 3251–3256. doi:10.1128/AEM.02248-07. PMC   2394955 . PMID   18378641.
  10. ↑ Zhou, R; Rana, T. M. (2013). "RNA-based mechanisms regulating host-virus interactions". Immunological Reviews. 253 (1): 97–111. doi:10.1111/imr.12053. PMC   3695692 . PMID   23550641.
  11. 1 2 3 4 5 6 Marklewitz, M.; Gloza-Rausch, F.; Kurth, A.; Kummerer, B. M.; Drosten, C.; Junglen, S. (2012). "First isolation of an Entomobirnavirus from free-living insects". Journal of General Virology. 93 (Pt 11): 2431–2435. doi: 10.1099/vir.0.045435-0 . PMID   22875257.
  12. 1 2 Zambon, R. A.; Nandakumar, M; Vakharia, V. N.; Wu, L. P. (2005). "The Toll pathway is important for an antiviral response in Drosophila". Proceedings of the National Academy of Sciences. 102 (20): 7257–62. Bibcode:2005PNAS..102.7257Z. doi: 10.1073/pnas.0409181102 . PMC   1129099 . PMID   15878994.
  13. ↑ Valanne, S; Wang, J. H.; Rämet, M (2011). "The Drosophila Toll signaling pathway". The Journal of Immunology. 186 (2): 649–56. doi: 10.4049/jimmunol.1002302 . PMID   21209287.
  14. ↑ Franz, A. W.; Sanchez-Vargas, I; Adelman, Z. N.; Blair, C. D.; Beaty, B. J.; James, A. A.; Olson, K. E. (2006). "Engineering RNA interference-based resistance to dengue virus type 2 in genetically modified Aedes aegypti". Proceedings of the National Academy of Sciences. 103 (11): 4198–203. Bibcode:2006PNAS..103.4198F. doi: 10.1073/pnas.0600479103 . PMC   1449670 . PMID   16537508.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.