Foot-and-mouth disease virus
Encyclopedia
The foot-and-mouth disease virus is the 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...

 that causes foot-and-mouth disease
Foot-and-mouth disease
Foot-and-mouth disease or hoof-and-mouth disease is an infectious and sometimes fatal viral disease that affects cloven-hoofed animals, including domestic and wild bovids...

. It is a picornavirus
Picornavirus
A picornavirus is a virus belonging to the family Picornaviridae. Picornaviruses are non-enveloped, positive-stranded RNA viruses with an icosahedral capsid. The genome RNA is unusual because it has a protein on the 5' end that is used as a primer for transcription by RNA polymerase...

, the prototypical member of the Aphthovirus
Aphthovirus
Aphthovirus is a viral genus of the family Picornaviridae. Aphthoviruses infect vertebrates, and include the causative agent of foot-and-mouth disease. Foot-and-mouth disease virus is the prototypic member of the genus Aphthovirus...

genus. The disease, which causes blisters in the mouth and feet of bovid
Bovid
A bovid is any of almost 140 species of cloven-hoofed ruminant mammal at least the males of which bear characteristic unbranching horns covered in a permanent sheath of keratin....

s and other cloven-hoofed animals, is highly infectious and a major plague of animal farming.

The virus particle (25-30 nm) has an icosahedral capsid
Capsid
A capsid is the protein shell of a virus. It consists of several oligomeric structural subunits made of protein called protomers. The observable 3-dimensional morphological subunits, which may or may not correspond to individual proteins, are called capsomeres. The capsid encloses the genetic...

 made of 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...

, without envelope, containing a single strand of ribonucleic acid (RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....

) containing a positive encoding of its genome
Genome
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....

. When the virus comes in contact with the membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...

 of a host cell, it binds to a receptor site
Membrane receptor
Cell surface receptors are specialized integral membrane proteins that take part in communication between the cell and the outside world...

 and triggers a folding-in of the membrane. Once the virus is inside the host cell, the capsid dissolves, and the RNA gets replicated, and translated into viral proteins by the cell's ribosome
Ribosome
A ribosome is a component of cells that assembles the twenty specific amino acid molecules to form the particular protein molecule determined by the nucleotide sequence of an RNA molecule....

s using a cap-independent mechanism driven by the internal ribosome entry site
Internal ribosome entry site
An internal ribosome entry site, abbreviated IRES, is a nucleotide sequence that allows for translation initiation in the middle of a messenger RNA sequence as part of the greater process of protein synthesis...

 element.

The synthesis of viral proteins include 2A 'cleavage' during translation. They include proteases that inhibit the sythesis of normal cell proteins, and other proteins that interact with different components of the host cell. The infected cell ends up producing large quantities of vial RNA and capsid proteins, which are assembled to form new viruses. After assembly, the host cell lyses
Lysis
Lysis refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a "lysate"....

 (bursts) and releases the new viruses.

The foot-and-mouth disease virus occurs in seven major serotypes: O, A, C, SAT-1, SAT-2, SAT-3, and Asia-1. These serotypes show some regionality, and the O serotype is most common.
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