Vesicular exanthema of swine virus
Encyclopedia
Vesicular exanthema of swine virus (VESV) is a virus
different from those causing Foot-and-Mouth Disease
(FMD) and Swine Vesicular Disease
(SVD) but it produces a disease in pigs
that is clinically indistinguishable from FMD and SVD. Unlike FMD it only affects pigs.
Currently, VESV is only a concern among California
n pig-farmers, otherwise, the disease is now, by and large, a historical curiosity. It was globally eradicated in swine in 1959.
along the Pacific coast
of the USA. These viruses are sometimes called San Miguel Sea Lion Virus. It is therefore assumed that the source of VESV was waste sea food fed to pigs or as garbage finding its way to pigs from farmed
-mink
fed seafood
.
in 1932. Because of its close similarity to FMD all the pigs were destroyed. It kept reappearing in California from time to time, the pigs being slaughtered each time. Then in 1952 the virus escaped from California in a train-load of infected pork. Garbage fed pig herds came down with the disease and it spread from them to neighbouring herds until herds in 43 states were affected. It was eventually stamped out in 1956 by a major slaughter policy combined with a ban on feeding uncooked garbage to pigs. It was declared an exotic disease in the USA in 1959
The only cases outside the USA were in slaughter pigs on ships from the USA bound for Hawaii
in 1947 and in pigs fed uncooked pork scraps from an American military base in Iceland
in 1955.
The source of the virus remained a mystery until 1972 when an essentially similar virus the San Miguel Sea Lion Virus (SMSV) was isolated from San Miguel Island
sea lions. When inoculated experimentally into pigs it caused typical signs of VESV.
, sheep, goats or any species other than the pigs and marine mammals.
* Fever up to 107 °F (41.7 °C).
* Vesicles are found on the epithelium
of the snout
, lips, nostrils, tongue
, feet and mammary glands.
* Very similar to FMD
* Epithelial lesions are identical to the other vesicular diseases
* No systemic lesions
Mortality is low but there may be some deaths in suckling pig
lets. Growing pigs may become debilitated.
tests to identify it. Serological methods such as complement fixation, serum neutralisation and PCR are available.
. Virus capsid is not enveloped, round with icosahedral symmetry
. The isometric capsid has a diameter of 35-39 nm. Capsids appear round to hexagonal in outline. The capsid surface structure reveals a regular pattern with distinctive features. The capsomer arrangement is clearly visible. Capsid with 32 cup-shaped depressions.
Physical chemistry
Under in vitro conditions virions are inactivated in acid environment of pH
3-5.
, single-stranded RNA
. Minor species of non-genomic nucleic acid
are also found in virions. The complete genome is 7900 nucleotides long. The 5'-end of the genome has a viral protein genome-linked (VPg
). The 3'-terminus has a poly (A)
tract.
Genomic organization
By itself, genomic nucleic acid is infectious
.
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...
different from those causing 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...
(FMD) and Swine Vesicular Disease
Swine vesicular disease
Swine vesicular disease is an acute, contagious viral disease of swine caused by the swine vesicular disease virus, an enterovirus. It is characterized by fever and vesicles with subsequent ulcers in the mouth and on the snout, feet, and teats...
(SVD) but it produces a disease in pigs
PIGS
PIGS is a four letter acronym that can stand for:* PIGS , Phosphatidylinositol glycan anchor biosynthesis, class S, a human gene* PIGS , the economies of Portugal, Italy , Greece and Spain...
that is clinically indistinguishable from FMD and SVD. Unlike FMD it only affects pigs.
Currently, VESV is only a concern among California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
n pig-farmers, otherwise, the disease is now, by and large, a historical curiosity. It was globally eradicated in swine in 1959.
Source of virus
Viruses that are virtually identical to VESV virus are present in marine mammals and fishFish
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...
along the Pacific coast
Pacific Coast
A country's Pacific coast is the part of its coast bordering the Pacific Ocean.-The Americas:Countries on the western side of the Americas have a Pacific coast as their western border.* Geography of Canada* Geography of Chile* Geography of Colombia...
of the USA. These viruses are sometimes called San Miguel Sea Lion Virus. It is therefore assumed that the source of VESV was waste sea food fed to pigs or as garbage finding its way to pigs from farmed
Factory farming
Factory farming is a term referring to the process of raising livestock in confinement at high stocking density, where a farm operates as a factory — a practice typical in industrial farming by agribusinesses. The main products of this industry are meat, milk and eggs for human consumption...
-mink
Mink
There are two living species referred to as "mink": the European Mink and the American Mink. The extinct Sea Mink is related to the American Mink, but was much larger. All three species are dark-colored, semi-aquatic, carnivorous mammals of the family Mustelidae, which also includes the weasels and...
fed seafood
Seafood
Seafood is any form of marine life regarded as food by humans. Seafoods include fish, molluscs , crustaceans , echinoderms . Edible sea plants, such as some seaweeds and microalgae, are also seafood, and are widely eaten around the world, especially in Asia...
.
History
VESV was first diagnosed in pigs in Southern CaliforniaSouthern California
Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...
in 1932. Because of its close similarity to FMD all the pigs were destroyed. It kept reappearing in California from time to time, the pigs being slaughtered each time. Then in 1952 the virus escaped from California in a train-load of infected pork. Garbage fed pig herds came down with the disease and it spread from them to neighbouring herds until herds in 43 states were affected. It was eventually stamped out in 1956 by a major slaughter policy combined with a ban on feeding uncooked garbage to pigs. It was declared an exotic disease in the USA in 1959
The only cases outside the USA were in slaughter pigs on ships from the USA bound for Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
in 1947 and in pigs fed uncooked pork scraps from an American military base in Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
in 1955.
The source of the virus remained a mystery until 1972 when an essentially similar virus the San Miguel Sea Lion Virus (SMSV) was isolated from San Miguel Island
San Miguel Island
San Miguel Island is the westernmost of California's Channel Islands, located across the Santa Barbara Channel in the Pacific Ocean, within Santa Barbara County, California. San Miguel is the sixth-largest of the eight Channel Islands at , including offshore islands and rocks. Prince Island, off...
sea lions. When inoculated experimentally into pigs it caused typical signs of VESV.
Transmission
Once established within a herd, transmission from pig to pig is by direct contact. Initiation of new outbreaks starts by feeding infected uncooked pork scraps.Symptoms
VESV does not affect cattleCattle
Cattle are the most common type of large domesticated ungulates. They are a prominent modern member of the subfamily Bovinae, are the most widespread species of the genus Bos, and are most commonly classified collectively as Bos primigenius...
, sheep, goats or any species other than the pigs and marine mammals.
* Fever up to 107 °F (41.7 °C).
* Vesicles are found on the epithelium
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
of the snout
Snout
The snout, or muzzle, is the protruding portion of an animal's face, consisting of its nose, mouth, and jaw.-Terminology:The term "muzzle", used as a noun, can be ambiguous...
, lips, nostrils, tongue
Tongue
The tongue is a muscular hydrostat on the floors of the mouths of most vertebrates which manipulates food for mastication. It is the primary organ of taste , as much of the upper surface of the tongue is covered in papillae and taste buds. It is sensitive and kept moist by saliva, and is richly...
, feet and mammary glands.
* Very similar to FMD
* Epithelial lesions are identical to the other vesicular diseases
* No systemic lesions
Mortality is low but there may be some deaths in suckling pig
Suckling pig
A suckling pig is a piglet fed on its mother's milk . In culinary, a suckling pig is slaughtered between the ages of two and six weeks. It is traditionally cooked whole, often roasted, in various cuisines...
lets. Growing pigs may become debilitated.
Diagnosis
This is the same as for suspected FMD and SVD and requires laboratoryLaboratory
A laboratory is a facility that provides controlled conditions in which scientific research, experiments, and measurement may be performed. The title of laboratory is also used for certain other facilities where the processes or equipment used are similar to those in scientific laboratories...
tests to identify it. Serological methods such as complement fixation, serum neutralisation and PCR are available.
Morphology
Virions consist of a capsidCapsid
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...
. Virus capsid is not enveloped, round with icosahedral symmetry
Icosahedral symmetry
A regular icosahedron has 60 rotational symmetries, and a symmetry order of 120 including transformations that combine a reflection and a rotation...
. The isometric capsid has a diameter of 35-39 nm. Capsids appear round to hexagonal in outline. The capsid surface structure reveals a regular pattern with distinctive features. The capsomer arrangement is clearly visible. Capsid with 32 cup-shaped depressions.
Physical chemistryPhysical chemistryPhysical chemistry is the study of macroscopic, atomic, subatomic, and particulate phenomena in chemical systems in terms of physical laws and concepts...
and Physical PropertyPhysical propertyA physical property is any property that is measurable whose value describes a physical system's state. The changes in the physical properties of a system can be used to describe its transformations ....
Under in vitro conditions virions are inactivated in acid environment of pHPH
In chemistry, pH is a measure of the acidity or basicity of an aqueous solution. Pure water is said to be neutral, with a pH close to 7.0 at . Solutions with a pH less than 7 are said to be acidic and solutions with a pH greater than 7 are basic or alkaline...
3-5.
Nucleic Acid
The genome is not segmented and contains a single molecule of linear positive-senseSense (molecular biology)
In molecular biology and genetics, sense is a concept used to compare the polarity of nucleic acid molecules, such as DNA or RNA, to other nucleic acid molecules...
, single-stranded RNA
RNA
Ribonucleic acid , or RNA, is one of the three major macromolecules that are essential for all known forms of life....
. Minor species of non-genomic nucleic acid
Nucleic acid
Nucleic acids are biological molecules essential for life, and include DNA and RNA . Together with proteins, nucleic acids make up the most important macromolecules; each is found in abundance in all living things, where they function in encoding, transmitting and expressing genetic information...
are also found in virions. The complete genome is 7900 nucleotides long. The 5'-end of the genome has a viral protein genome-linked (VPg
VPg
VPg is a protein attached to the 5' end of RNA during RNA synthesis in a wide variety of viruses including Picornaviridae such as Foot-and-mouth disease and poliovirus . VPg stands for "viral protein genome-linked".-Attachment during RNA synthesis:...
). The 3'-terminus has a poly (A)
Poly(A)-binding protein
Poly-binding protein is a RNA-binding protein which binds to the poly tail of mRNA. The poly tail is located on the 3' end of mRNA...
tract.
Genomic organizationGenomic organizationright|thumb|300px|Genome sizes and corresponding composition of six major model organisms as pie charts. The increase in [[genome]] size correlates with the vast expansion of noncoding and repeat [[DNA]] sequences in more complex...
and Viral replicationViral replicationViral replication is the term used by virologists to describe the formation of biological viruses during the infection process in the target host cells. Viruses must first get into the cell before viral replication can occur. From the perspective of the virus, the purpose of viral replication is...
By itself, genomic nucleic acid is infectiousInfectious disease
Infectious diseases, also known as communicable diseases, contagious diseases or transmissible diseases comprise clinically evident illness resulting from the infection, presence and growth of pathogenic biological agents in an individual host organism...
.
Management control and prevention
- No vaccines are available.
- The cooked garbage policyHistory of waste managementHistorically, the amount of wastes generated by human population was insignificant mainly due to the low population densities, coupled with the fact there was very little exploitation of natural resources...
in the USA should prevent its reappearance but it is conceivable that an ignorant or careless person may break the rules. - If you farm in California do not feed waste sea food to your pigs. Also, do not allow anyone working in your herdHerdHerd refers to a social grouping of certain animals of the same species, either wild or domestic, and also to the form of collective animal behavior associated with this or as a verb, to herd, to its control by another species such as humans or dogs.The term herd is generally applied to mammals,...
to take sandwiches or other food into the pig buildings. Provide a designated eating place for them away from the pigs. This is a good policy anyway. - Monitoring of the San Miguel Sea Lion Virus is a good precautionary measure.
External links
- ICTVdB - The Universal Virus Database, version 4. http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/