Birnaviridae
Encyclopedia
The birnaviridae are a family of virus
es, including the following genera:
The birnaviridae are type-III viruses in the Baltimore classification
, which means they have a double-stranded RNA genome. The other family of type-III viruses is the Reoviridae
.
encodes several proteins:
The Birnaviridae 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.
The large RNA segment, segment A, of birnaviruses code
s for a polyprotein (N-VP2-VP4-VP3-C) 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.
VP4 protein
is involved in generating VP2 and VP3. recombinant
VP3 is more immunogenic than recombinant VP2.
Infectious pancreatic necrosis virus (IPNV), a birnavirus, is an important pathogen
in fish
farms. Analyses of viral protein
s showed that VP2 is the major structural
and immunogenic polypeptide of the virus. 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 acid
s of the conserved
C-terminal are probably the most important in inducing an immune response for the protection of animal
s.
Non structural
protein
VP5 is found in RNA segment A. The function of this small viral protein is unknown.
Virus
A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...
es, including the following genera:
- Genus Aquabirnavirus; type species: Infectious pancreatic necrosis virus
- Genus Avibirnavirus; type species: Infectious bursal disease virus
- Genus Blosnavirus; type species: Blotched snakehead virus
- Genus Entomobirnavirus; type species: Drosophila X virusDrosophila X virusDrosophila X virus is a virus that can infect fruit flies of the genus Drosophila and is commonly used to study innate immunity in the common model organism Drosophila melanogaster. The viral capsid is roughly hexagonal and icosahedrally symmetrical. The genome of the virus consists of two linear,...
The birnaviridae are type-III viruses in the Baltimore classification
Baltimore classification
The Baltimore classification, developed by David Baltimore, is a virus classification system that groups viruses into families, depending on their type of genome and their method of replication....
, which means they have a double-stranded RNA genome. The other family of type-III viruses is the Reoviridae
Reoviridae
Reoviridae is a family of viruses that can affect the gastrointestinal system and respiratory tract. Viruses in the family Reoviridae have genomes consisting of segmented, double-stranded RNA...
.
Birnaviridae proteins
The Birnaviridae genomeGenome
In modern molecular biology and genetics, the genome is the entirety of an organism's hereditary information. It is encoded either in DNA or, for many types of virus, in RNA. The genome includes both the genes and the non-coding sequences of the DNA/RNA....
encodes several proteins:
The Birnaviridae RNA-directed RNA polymerase (VP1), which lacks the highly conserved Gly-Asp-Asp (GDD) sequence, a component of the proposed catalytic
Catalysis
Catalysis is the change in rate of a chemical reaction due to the participation of a substance called a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. A catalyst may participate in multiple chemical transformations....
site of this enzyme family that exists in the conserved
Sequence alignment
In bioinformatics, a sequence alignment is a way of arranging the sequences of DNA, RNA, or protein to identify regions of similarity that may be a consequence of functional, structural, or evolutionary relationships between the sequences. Aligned sequences of nucleotide or amino acid residues are...
motif VI of the palm domain of other RNA-directed RNA polymerases.
The large RNA segment, segment A, of birnaviruses code
Genetic code
The genetic code is the set of rules by which information encoded in genetic material is translated into proteins by living cells....
s for a polyprotein (N-VP2-VP4-VP3-C) that is processed into the major structural proteins
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
of the virion: VP2, VP3 (a minor structural component of the virus), and into the putative protease
Protease
A protease is any enzyme that conducts proteolysis, that is, begins protein catabolism by hydrolysis of the peptide bonds that link amino acids together in the polypeptide chain forming the protein....
VP4.
VP4 protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
is involved in generating VP2 and VP3. recombinant
Recombinant DNA
Recombinant DNA molecules are DNA sequences that result from the use of laboratory methods to bring together genetic material from multiple sources, creating sequences that would not otherwise be found in biological organisms...
VP3 is more immunogenic than recombinant VP2.
Infectious pancreatic necrosis virus (IPNV), a birnavirus, is an important pathogen
Pathogen
A pathogen gignomai "I give birth to") or infectious agent — colloquially, a germ — is a microbe or microorganism such as a virus, bacterium, prion, or fungus that causes disease in its animal or plant host...
in fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...
farms. Analyses of viral protein
Viral protein
A viral protein is a protein generated by a virus.Many are structural, forming the viral envelope and capsid. However, there are also viral nonstructural proteins and viral regulatory and accessory proteins.More than 490 have been identified....
s showed that VP2 is the major structural
Secondary structure
In biochemistry and structural biology, secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids...
and immunogenic polypeptide of the virus. All neutralizing monoclonal antibodies
Monoclonal antibodies
Monoclonal antibodies are monospecific antibodies that are the same because they are made by identical immune cells that are all clones of a unique parent cell....
are specific to VP2 and bind to continuous or discontinuous epitopes. The variable domain of VP2 and the 20 adjacent amino acid
Amino acid
Amino acids are molecules containing an amine group, a carboxylic acid group and a side-chain that varies between different amino acids. The key elements of an amino acid are carbon, hydrogen, oxygen, and nitrogen...
s of the conserved
Conserved sequence
In biology, conserved sequences are similar or identical sequences that occur within nucleic acid sequences , protein sequences, protein structures or polymeric carbohydrates across species or within different molecules produced by the same organism...
C-terminal are probably the most important in inducing an immune response for the protection of animal
Animal
Animals are a major group of multicellular, eukaryotic organisms of the kingdom Animalia or Metazoa. Their body plan eventually becomes fixed as they develop, although some undergo a process of metamorphosis later on in their life. Most animals are motile, meaning they can move spontaneously and...
s.
Non structural
Secondary structure
In biochemistry and structural biology, secondary structure is the general three-dimensional form of local segments of biopolymers such as proteins and nucleic acids...
protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
VP5 is found in RNA segment A. The function of this small viral protein is unknown.