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22  structures 12  species 0  interactions 12  sequences 1  architecture

Family: Birna_VP4 (PF01768)

Summary: Birnavirus VP4 protein

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This is the Wikipedia entry entitled "Birnaviridae". More...

Birnaviridae Edit Wikipedia article

Infectious bursal disease virus particle
Virus classification e
(unranked): Virus
Realm: Riboviria
Kingdom: Orthornavirae
Phylum: incertae sedis
Family: Birnaviridae

Birnaviridae is a family of double-stranded RNA viruses.[1] Salmonid fish, birds and insects serve as natural hosts. There are currently 11 species in this family, divided among seven genera.[2] 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.[2][3]


Viruses in family Birnaviridae are non-enveloped, with icosahedral single-shelled geometries, and T=13 symmetry. The diameter is around 70 nm.[2][3]


Genome of infectious bursal disease virus of family Birnaviridae

The genome is composed of linear, bi-segmented, double-stranded RNA. It is around 5.9–6.9 kbp in length and codes for five to six proteins. Birnaviruses encode the following proteins:

RNA-directed RNA polymerase (VP1), which lacks the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic site of this enzyme family that exists in the conserved motif VI of the palm domain of other RNA-directed RNA polymerases.[4]

The large RNA segment, segment A, of birnaviruses codes for a polyprotein (N-VP2-VP4-VP3-C) [5] that is processed into the major structural proteins of the virion: VP2, VP3 (a minor structural component of the virus), and into the putative protease VP4.[5] VP4 protein is involved in generating VP2 and VP3.[5] recombinant VP3 is more immunogenic than recombinant VP2.[6]

Infectious pancreatic necrosis virus (IPNV), a birnavirus, is an important pathogen in fish farms. Analyses of viral proteins showed that VP2 is the major structural and immunogenic polypeptide of the virus.[7][8] All neutralizing monoclonal antibodies are specific to VP2 and bind to continuous or discontinuous epitopes. The variable domain of VP2 and the 20 adjacent amino acids of the conserved C-terminal are probably the most important in inducing an immune response for the protection of animals.[7]

Non structural protein VP5 is found in RNA segment A.[citation needed] The function of this small viral protein is unknown. It is believed to be involved in influencing apoptosis, but studies are not completely concurring. The protein can not be found in the virion.

Life cycle

Viral replication is cytoplasmic. Entry into the host cell is achieved by cell receptor endocytosis. Replication follows the double-stranded RNA virus replication model in the cytoplasm. Double-stranded RNA virus transcription is the method of transcription in cytoplasm. The virus is released by budding. Salmonid fish (Aquabirnavirus), young sexually immature chickens (Avibirnavirus), insects (Entomobirnavirus), and blotched snakehead fish (Blosnavirus) as the natural host. Transmission routes are contact.[2][3]


Phylogenetic tree of Birnaviridae

The following genera are recognized:


  1. ^ Delmas, B; Attoui, H; Ghosh, S; Malik, YS; Mundt, E; Vakharia, VN; Ictv Report, Consortium (January 2019). "ICTV virus taxonomy profile: Birnaviridae". The Journal of General Virology. 100 (1): 5–6. doi:10.1099/jgv.0.001185. PMID 30484762.
  2. ^ a b c d "Birnaviridae—Birnaviridae—dsRNA Viruses". International Committee on Taxonomy of Viruses (ICTV). Retrieved 16 October 2019.
  3. ^ a b c "Viral Zone". ExPASy. Retrieved 12 June 2015.
  4. ^ Shwed PS, Dobos P, Cameron LA, Vakharia VN, Duncan R (May 2002). "Birnavirus VP1 proteins form a distinct subgroup of RNA-dependent RNA polymerases lacking a GDD motif". Virology. 296 (2): 241–250. doi:10.1006/viro.2001.1334. PMID 12069523.
  5. ^ a b c Jagadish MN, Staton VJ, Hudson PJ, Azad AA (March 1988). "Birnavirus precursor polyprotein is processed in Escherichia coli by its own virus-encoded polypeptide". J. Virol. 62 (3): 1084–7. doi:10.1128/JVI.62.3.1084-1087.1988. PMC 253673. PMID 2828658.
  6. ^ Moon CH, Do JW, Cha SJ, Bang JD, Park MA, Yoo DJ, Lee JM, Kim HG, Chung DK, Park JW (October 2004). "Comparison of the immunogenicity of recombinant VP2 and VP3 of infectious pancreatic necrosis virus and marine birnavirus". Arch. Virol. 149 (10): 2059–68. doi:10.1007/s00705-004-0339-2. PMID 15669113. S2CID 22958612.
  7. ^ a b Heppell J, Tarrab E, Lecomte J, Berthiaume L, Arella M (December 1995). "Strain variability and localization of important epitopes on the major structural protein (VP2) of infectious pancreatic necrosis virus". Virology. 214 (1): 40–9. doi:10.1006/viro.1995.9956. PMID 8525637.
  8. ^ Nobiron I, Galloux M, Henry C, Torhy C, Boudinot P, Lejal N, Da Costa B, Delmas B (February 2008). "Genome and polypeptides characterization of Tellina virus 1 reveals a fifth genetic cluster in the Birnaviridae family". Virology. 371 (2): 350–61. doi:10.1016/j.virol.2007.09.022. PMID 17976679.

External links

This page is based on a Wikipedia article. The text is available under the Creative Commons Attribution/Share-Alike License.

This tab holds the annotation information that is stored in the Pfam database. As we move to using Wikipedia as our main source of annotation, the contents of this tab will be gradually replaced by the Wikipedia tab.

Birnavirus VP4 protein Provide feedback

VP4 is a viral protease [1]. The large RNA segment of birnaviruses codes for a polyprotein (N-VP2-VP4-VP3-C) [1].

Literature references

  1. Jagadish MN, Staton VJ, Hudson PJ, Azad AA; , J Virol 1988;62:1084-1087.: Birnavirus precursor polyprotein is processed in Escherichia coli by its own virus-encoded polypeptide. PUBMED:2828658 EPMC:2828658

External database links

This tab holds annotation information from the InterPro database.

InterPro entry IPR025775

Viruses of the Birnaviridae family infect animal species belonging to vertebrates, molluscs, insects and rotifers and are characterised by their bi- segmented double-stranded RNA genome (segments A and B). Segment A encodes two overlapping reading frames and the larger open reading frame encodes a polyprotein (NH2-pVP2-VP4-VP3-COOH). The polyprotein is processed through the proteolytic activity of VP4 to generate pVP2 and VP3. During virus assembly pVP2 is further processed by VP4 to generate the capsid protein VP2 and structural peptides. Evolutionarily, the VP4 protease of the Birnaviridae family belongs to clan SJ and family S50 [ PUBMED:10666235 , PUBMED:16584747 , PUBMED:17553791 ].

The birnavirus VP4 protease domain displays a catalytic serine/lysine dyad in its active site. The birnavirus VP4 protease domain has an alpha/beta fold [ PUBMED:16584747 , PUBMED:17553791 ].

Domain organisation

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Seed source: Pfam-B_946 (release 4.2)
Previous IDs: none
Type: Family
Sequence Ontology: SO:0100021
Author: Bateman A
Number in seed: 3
Number in full: 12
Average length of the domain: 264.80 aa
Average identity of full alignment: 26 %
Average coverage of the sequence by the domain: 25.75 %

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HMM build commands:
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 61295632 -E 1000 --cpu 4 HMM pfamseq
Model details:
Parameter Sequence Domain
Gathering cut-off 24.0 24.0
Trusted cut-off 27.7 25.7
Noise cut-off 23.6 22.8
Model length: 259
Family (HMM) version: 19
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Species distribution

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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Birna_VP4 domain has been found. There are 22 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein sequence.

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