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[[Image:Polio EM PHIL 1875 lores.png|200 px||right|]]
[[Image:Polio EM PHIL 1875 lores.png|200 px||right|]]
{{Taxobox | color=violet
{{Taxobox | color=violet
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| order = Picornavirales
| order = Picornavirales
| familia = Picornaviridae
| familia = Picornaviridae
| genus = ''[[Enterovirus]]''
| genus = Enterovirus
| sero_complex = Poliovirus}}
| species = Poliovirus}}


==Description and significance==
==Description and significance==


Poliovirus was first isolated by Karl Landersteiner and Erwin Popper in 1909.   
Poliovirus is an [[enteroviruses]] which is a RNA virus that is stable and survive in acidic conditions.
Polioviruses are enteroviruses which are RNA viruses that are stable and survive in acidic conditions.
Poliovirus was first isolated by [[Karl Landersteiner]] and [[Erwin Popper]] in 1909.  They proved that a virus caused the paralysis and not a bacterium. Karl Landsteiner presented that the cause of poliomyelitis could be experimentally transmitted to monkeys by injecting them with material that was made by grinding up the spinal cords of children who died from poliomyelitis.
 
Describe the appearance, habitat, etc. of the organism, and why it is important enough to have its genome sequenced. Describe how and where it was isolated. Include a picture or two (with sources) if you can find them.
[[Image:Poliovirus1.png|frame|'''Poliovirus''']]
[[Image:Poliovirus1.png|frame|'''Poliovirus''']]


==Genome structure==
==Genome structure==


Poliovirus is made up of a RNA genome and a protein capsid.  The genome is a linear, single-stranded, positive-strand RNA and it is approximately 7,500 nucleotides long.  The viral component is about 300 Angstrom in diameter with icosahdral symmetry.  Poliovirus is commonly known as the most important and basic virus because of its short genome and simple composition.
Poliovirus is made up of a [[RNA]] genome and a protein capsid.  The RNA genome is a linear, single-stranded, [[positive-strand]] RNA.  It is about 7,500 [[nucleotides]] long.  The viral component is about 300 [[Ångström]] wide with [[icosahdral]] symmetry.  Poliovirus is composed of carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur.
 
Poliovirus builds its RNA genes and its protective protein capsid from these elements.  Poliovirus has three [[serotypes]]; PV1, PV2, and PV3.  There are many strains of each serotype.  The three serotypes are very infectious, but differ in the protein capsid.  PV1 is the most common and harmful serotype.  Poliovirus is commonly known as the most important and basic virus because of its short genome and simple structure.
 
Describe the size and content of the genome. How many chromosomes?  Circular or linear?  Other interesting features?  What is known about its sequence?
Does it have any plasmids?  Are they important to the organism's lifestyle?


==Cell structure and metabolism==
==Cell structure and metabolism==
[[Image:Poliovirus_life_cycle.png|580 px|]]
[[Image:Poliovirus_life_cycle.png|580 px|]]


The cellular life cycle of poliovirus. It is initiated by binding of a poliovirion to the cell surface macromolecule CD155, which functions as the receptor (1). Uncoating of the viral RNA is mediated by receptor-dependent destabilization of the virus capsid (2). Cleavage of the viral protein VPg is performed by a cellular phosphodiesterase, and translation of the viral RNA occurs by a cap-independent (IRES-mediated) mechanism (3). Proteolytic processing of the viral polyprotein yields mature structural and non-structural proteins (4). The positive-sense RNA serves as template for complementary negative-strand synthesis, thereby producing a double-stranded RNA (replicative form, RF) (5). Initiation of many positive strands from a single negative strand produces the partially single-stranded replicative intermediate (RI) (6). The newly synthesized positive-sense RNA molecules can serve as templates for translation (7) or associate with capsid precursors to undergo encapsidation and induce the maturation cleavage of VP0 (8), which ultimately generates progeny virions. Lysis of the infected cell results in release of infectious progeny virions (9).
The cellular life cycle of poliovirus begins by binding of a poliovirion to the host cell surface receptor, CD155 (1). Destabilization of the virus capsid which is receptor dependent uncoats the viral RNA (2). Cellular phosphodiesterase cleaves the viral protein VPg and viral RNA is translated by a cap-independent (IRES-mediated) process (3). The viral polyprotein generates mature structural and non-structural proteins by proteolytic processing (4). The positive-sense RNA acts as template for complementary negative-strand synthesis, which constructs a double-stranded RNA (replicative form, RF) (5). Initiation of many positive strands from a single negative strand produces the partially single-stranded replicative intermediate (RI) (6). The synthesized positive-sense RNA molecules can act as templates for translation (7) or associate with capsid precursors to undergo encapsidation and the maturation cleavage of VP0 (8), which produces virions. The infected cell bursts and releases infectious viruses into the bloodstream(9).
[http://commons.wikimedia.org/wiki/Image:Poliovirus_life_cycle.png]
[http://commons.wikimedia.org/wiki/Image:Poliovirus_life_cycle.png]


==Ecology==
==Ecology==


Humans are the exclusive natural host for poliovirus.  It cannot naturally infect other species.
Humans are the exclusive natural host for poliovirus.  It cannot naturally infect other species. Monkeys and chimpanzees can be infected with poliovirus experimentally, but not naturally.  Poliovirus is spread through sewage by infected people who pass their faeces.  Even though an individual is immune to poliovirus, they can pass the virus through their faeces.
 
Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.


==Pathology==
==Pathology==


Poliovirus causes the viral disease, poliomyelitis.  Poliomyelitis is an extremely infectious disease.  Humans are the exclusive natural host for poliovirus.  It cannot naturally infect other species.  The virus takes over the nervous system and cause paralysis in hoursPoliovirus enters the body through the mouth and replicates in the throat and intestineOnce the virus remains stable in the intestine, it can enter the blood stream and pass onto the central nervous system.
Poliovirus causes the viral disease, [[poliomyelitis]].  Poliomyelitis is a very infectious disease.  Humans are the exclusive natural host for poliovirus.  It cannot naturally infect other species.  There are two types of poliomyelitis; nonparalytic polio and paralytic polio.  Nonparalytic polio is the main type of polio that doesn't lead to paralysis ([[abortive poliomyelitis]]).  About 5-10% of people are affected by nonparalytic polioAbout 1% of people are affected by paralytic polioThere are three types of paralytic poliomyelitis; [[spinal polio]], [[bulbar polio]], and [[bulbospinal polio]].


As poliovirus replicates, it damages motor neurons which control the muscles for swallowing, circulation, respiration, and the trunk, arms, and legs.  The damage of the motor neurons are irreversible and can cause a condition known as acute flaccid paralysis (AFP) which affects the limbs.  Paralysis involving the trunk and muscles of the thorax and abdomen can result in quadriplegia.  For bulbar polio, a more severe case of polio, poliovirus attacks the motor neurons of the brain stem which cause difficulty in swallowing and speaking.  Without respiratory support, bulbar polio can lead to death.  In the 1940s and 50s, people infected with polio that affected their respiratory muscles were immobilized in "iron lungs" - metal cylinders that were worked like a pair of bellows to regulate breathing and keep them alive.  Today the iron lung has been replaced by a positive pressure ventilator.
[[Spinal polio]] is the most common paralytic polio.  The poliovirus invades motor neurons in the spinal cord which may cause paralysis of the muscles that control breathing as well as the arms and legs.  


In countries with poor sanitation, poliovirus can be spread to others by faeces of people who are infected by the virusIt can also infect vaccinated people; they will not develop polio, but can carry this virus in their gastrointestinal tract and pass it on to others.   
[[Bulbar polio]] is the more severe case of poliomyelitis.  The poliovirus attacks the motor neurons of the brain stem and causes difficulty in swallowing and speakingWithout respiratory support, bulbar polio can lead to death.  In the 1940s and 50s, people infected with bulbar polio were treated with [["iron lungs"]] - metal cylinders that were worked like a pair of bellows to regulate breathingToday, the positive pressure ventilator replaced the iron lung.


Symptoms of individuals who are infected include fever, headache, vomitting, stiffness in the neck and pain in the back and neckPoliovirus can also lead to paralysis, usually in the legs.  Some people infected with this virus do not have any symptoms and aren't aware they have been infected.
[[Bulbospinal polio]] is a combination of bulbar and spinal polioBulbospinal polio can lead to paralysis of the arms and legs.  It may also affect breathing, swallowing and heart function.


There is no known cure for poliomyelitis.  
The poliovirus can take over the nervous system and can cause paralysis in hours. Poliovirus enters the body through the mouth and multiplies in the throat and intestine.  Once the virus remains stable in the intestine, it can enter the blood stream and pass onto the [[central nervous system]]. 


How does this organism cause disease?  Human, animal, plant hosts?  Virulence factors, as well as patient symptoms.
As poliovirus replicates, it damages [[motor neurons]] which affect the muscles for swallowing, circulation, respiration, as well as the trunk, arms, and legs.  The damage of the motor neurons are irreparable and can cause acute [[flaccid paralysis]] (AFP) which affects the limbs.  Paralysis of the trunk and muscles of the thorax and abdomen can result in [[quadriplegia]].


==Application to Biotechnology==
In countries with poor sanitation, poliovirus can be spread to others by faeces of people who are infected by the virus. It can also infect vaccinated people; they will not develop polio, but they can carry this virus in their [[gastrointestinal tract]] and pass it on to others. 
Does this organism produce any useful compounds or enzymes? What are they and how are they used?


Symptoms of infected individuals include headache, fever, vomiting, stiffness and pain in the neck and back.  Poliovirus can also lead to paralysis, usually in the legs.  Some people infected with this virus do not have any symptoms so they do not know they have been infected.


Unfortunately, there is no known cure for poliomyelitis.


==Current Research==
==Current Research==
'''Researchers Use Crippled Poliovirus to Attack Brain Cancer'''
In an experiment to attack brain cancer, Dr. Matthias Gromeier and researchers joined properties of poliovirus with an innocuous genetic coding element from the common cold.  The new virus that resulted from the experiment showed a strong anti-cancer property that quickly killed cancer cell cultures and in animals.  Even though the new virus contained cancer-killing properties of poliovirus, it did not cause polio.  The altered poliovirus killed cancer cells from brain tumors as well as breast and colon cancer metastases within four to six hours.  The researchers disabled poliovirus from killing normal brain cells while killing cancer cells in the brain.  Researchers switched a genetic property from the common cold “rhinovirus” with a corresponding genetic property from poliovirus.  The genetic element, called an internal ribosomal entry site ‘IRES,’ allows a virus to express its own genetic information inside the host cell it invaded.  Poliovirus has a natural affinity to invade the brain.  Poliovirus invades brain cells by binding to the CD155 receptor on the surface of motor neurons.  Dr. Gromeier demonstrated that brain tumors over-produce the CD155 receptor, which makes the cell in the brain tumors more susceptible to poliovirus infection.  The altered poliovirus enters the normal motor neurons because it shares the same CD155 receptor as brain tumor cells, but it can’t grow in normal neurons.  Tests were done on mice and non-human primates and the results indicated that the altered poliovirus kills brain tumor cells, but it doesn’t damage normal motor neurons.  The poliovirus would be injected into the brain tumor and it would find and destroy cancer cells without being detected by the body’s immune system.  Dr. Gromeier stated, “Cell differ in terms of how well-suited they are to a particular virus.  Every cell type has unique cellular proteins that can either support or block viral function, and we believe differences in these proteins account for the modified virus’ inability to infect normal brain cells.”
'''First Animal Model Developed for Oral Infection of Human Poliovirus'''


In the August 2007 issue of Journal of Virology, it was reported that researchers developed an animal model for oral poliovirus infection.  Researchers were trying to find new ways to prevent the spread of the virus in countries with poor conditions.  In the study, the mice that lacked the interferon receptor gene (IFNAR) and carried the human poliovirus receptor gene were affected by the oral ingestion of poliovirus.  Nine days after the ingestion, the mice died and the poliovirus was found in their small intestines and digestive tracts.  The mice that expressed the interferon receptor gene (IFNAR) were found to be less affected by the virus.  These results show that the interferon receptor gene (IFNAR) is significant in determining how permissive the poliovirus is in the digestive tract as well as the production of virus-specific immune responses to the virus by the oral route.  The researchers stated, “Thus, hPVR-Tg/IfnarKO are considered to be the first oral infection model for poliovirus.”


'''Researchers Use Poliovirus to Destroy Neuroblastoma in Mice'''
Researchers from Stony Brook University reported that a innocuous form of poliovirus can destroy neuroblastoma tumors in vaccinated mice.  Poliovirus kills the host cell it infects so that it can make copies of itself.  The researchers injected a weak strain of poliovirus into neuroblastoma tumors that have been transplanted into 12 mice.  The poliovirus destroyed the neuroblastoma tumors in all the mice, but tumors reappeared in two mice at the end of the experimental period.  The researchers also found out that the injection of poliovirus inhibited new tumor growth in mice.  This was important because new growth is common in neuroblastoma even after chemotherapy.


==References==
==References==


http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=138953&lvl=3&p=cdd&p=taxonomy&lin=f&keep=1&srchmode=1&unlock
*[http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=138953&lvl=3&p=cdd&p=taxonomy&lin=f&keep=1&srchmode=1&unlock]
 
*[http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.052.0.01.001.htm]
 
*[http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?lvl=0&id=12080]
 
*[http://www.ncbi.nlm.nih.gov/pubmed/10618373]


http://en.wikipedia.org/wiki/Poliovirus
*[http://query.nytimes.com/gst/fullpage.html?sec=health&res=9A03E2D81739F933A1575AC0A963948260]


http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.052.0.01.001.htm
*[http://www.sciencemag.org/cgi/content/abstract/229/4720/1358]


http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?lvl=0&id=12080
*[http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1490301]


http://www.ncbi.nlm.nih.gov/pubmed/10618373
*[http://www.medicalnewstoday.com/articles/65439.php]


http://query.nytimes.com/gst/fullpage.html?sec=health&res=9A03E2D81739F933A1575AC0A963948260
*[http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1490301#b14]


http://www.sciencemag.org/cgi/content/abstract/229/4720/1358
*[http://www.medicalnewstoday.com/articles/4800.php]


http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1490301
*[http://www.medicalnewstoday.com/articles/80204.php][[Category:Suggestion Bot Tag]]

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Polio EM PHIL 1875 lores.png
Poliovirus
Virus classification
Group: ssRNA viruses IV
Family: Picornaviridae
Genus: Enterovirus
Species: Poliovirus

Description and significance

Poliovirus is an enteroviruses which is a RNA virus that is stable and survive in acidic conditions. Poliovirus was first isolated by Karl Landersteiner and Erwin Popper in 1909. They proved that a virus caused the paralysis and not a bacterium. Karl Landsteiner presented that the cause of poliomyelitis could be experimentally transmitted to monkeys by injecting them with material that was made by grinding up the spinal cords of children who died from poliomyelitis.

Poliovirus

Genome structure

Poliovirus is made up of a RNA genome and a protein capsid. The RNA genome is a linear, single-stranded, positive-strand RNA. It is about 7,500 nucleotides long. The viral component is about 300 Ångström wide with icosahdral symmetry. Poliovirus is composed of carbon, hydrogen, nitrogen, oxygen, phosphorus and sulphur. Poliovirus builds its RNA genes and its protective protein capsid from these elements. Poliovirus has three serotypes; PV1, PV2, and PV3. There are many strains of each serotype. The three serotypes are very infectious, but differ in the protein capsid. PV1 is the most common and harmful serotype. Poliovirus is commonly known as the most important and basic virus because of its short genome and simple structure.

Cell structure and metabolism

Poliovirus life cycle.png

The cellular life cycle of poliovirus begins by binding of a poliovirion to the host cell surface receptor, CD155 (1). Destabilization of the virus capsid which is receptor dependent uncoats the viral RNA (2). Cellular phosphodiesterase cleaves the viral protein VPg and viral RNA is translated by a cap-independent (IRES-mediated) process (3). The viral polyprotein generates mature structural and non-structural proteins by proteolytic processing (4). The positive-sense RNA acts as template for complementary negative-strand synthesis, which constructs a double-stranded RNA (replicative form, RF) (5). Initiation of many positive strands from a single negative strand produces the partially single-stranded replicative intermediate (RI) (6). The synthesized positive-sense RNA molecules can act as templates for translation (7) or associate with capsid precursors to undergo encapsidation and the maturation cleavage of VP0 (8), which produces virions. The infected cell bursts and releases infectious viruses into the bloodstream(9). [1]

Ecology

Humans are the exclusive natural host for poliovirus. It cannot naturally infect other species. Monkeys and chimpanzees can be infected with poliovirus experimentally, but not naturally. Poliovirus is spread through sewage by infected people who pass their faeces. Even though an individual is immune to poliovirus, they can pass the virus through their faeces.

Pathology

Poliovirus causes the viral disease, poliomyelitis. Poliomyelitis is a very infectious disease. Humans are the exclusive natural host for poliovirus. It cannot naturally infect other species. There are two types of poliomyelitis; nonparalytic polio and paralytic polio. Nonparalytic polio is the main type of polio that doesn't lead to paralysis (abortive poliomyelitis). About 5-10% of people are affected by nonparalytic polio. About 1% of people are affected by paralytic polio. There are three types of paralytic poliomyelitis; spinal polio, bulbar polio, and bulbospinal polio.

Spinal polio is the most common paralytic polio. The poliovirus invades motor neurons in the spinal cord which may cause paralysis of the muscles that control breathing as well as the arms and legs.

Bulbar polio is the more severe case of poliomyelitis. The poliovirus attacks the motor neurons of the brain stem and causes difficulty in swallowing and speaking. Without respiratory support, bulbar polio can lead to death. In the 1940s and 50s, people infected with bulbar polio were treated with "iron lungs" - metal cylinders that were worked like a pair of bellows to regulate breathing. Today, the positive pressure ventilator replaced the iron lung.

Bulbospinal polio is a combination of bulbar and spinal polio. Bulbospinal polio can lead to paralysis of the arms and legs. It may also affect breathing, swallowing and heart function.

The poliovirus can take over the nervous system and can cause paralysis in hours. Poliovirus enters the body through the mouth and multiplies in the throat and intestine. Once the virus remains stable in the intestine, it can enter the blood stream and pass onto the central nervous system.

As poliovirus replicates, it damages motor neurons which affect the muscles for swallowing, circulation, respiration, as well as the trunk, arms, and legs. The damage of the motor neurons are irreparable and can cause acute flaccid paralysis (AFP) which affects the limbs. Paralysis of the trunk and muscles of the thorax and abdomen can result in quadriplegia.

In countries with poor sanitation, poliovirus can be spread to others by faeces of people who are infected by the virus. It can also infect vaccinated people; they will not develop polio, but they can carry this virus in their gastrointestinal tract and pass it on to others.

Symptoms of infected individuals include headache, fever, vomiting, stiffness and pain in the neck and back. Poliovirus can also lead to paralysis, usually in the legs. Some people infected with this virus do not have any symptoms so they do not know they have been infected.

Unfortunately, there is no known cure for poliomyelitis.

Current Research

Researchers Use Crippled Poliovirus to Attack Brain Cancer

In an experiment to attack brain cancer, Dr. Matthias Gromeier and researchers joined properties of poliovirus with an innocuous genetic coding element from the common cold. The new virus that resulted from the experiment showed a strong anti-cancer property that quickly killed cancer cell cultures and in animals. Even though the new virus contained cancer-killing properties of poliovirus, it did not cause polio. The altered poliovirus killed cancer cells from brain tumors as well as breast and colon cancer metastases within four to six hours. The researchers disabled poliovirus from killing normal brain cells while killing cancer cells in the brain. Researchers switched a genetic property from the common cold “rhinovirus” with a corresponding genetic property from poliovirus. The genetic element, called an internal ribosomal entry site ‘IRES,’ allows a virus to express its own genetic information inside the host cell it invaded. Poliovirus has a natural affinity to invade the brain. Poliovirus invades brain cells by binding to the CD155 receptor on the surface of motor neurons. Dr. Gromeier demonstrated that brain tumors over-produce the CD155 receptor, which makes the cell in the brain tumors more susceptible to poliovirus infection. The altered poliovirus enters the normal motor neurons because it shares the same CD155 receptor as brain tumor cells, but it can’t grow in normal neurons. Tests were done on mice and non-human primates and the results indicated that the altered poliovirus kills brain tumor cells, but it doesn’t damage normal motor neurons. The poliovirus would be injected into the brain tumor and it would find and destroy cancer cells without being detected by the body’s immune system. Dr. Gromeier stated, “Cell differ in terms of how well-suited they are to a particular virus. Every cell type has unique cellular proteins that can either support or block viral function, and we believe differences in these proteins account for the modified virus’ inability to infect normal brain cells.”

First Animal Model Developed for Oral Infection of Human Poliovirus

In the August 2007 issue of Journal of Virology, it was reported that researchers developed an animal model for oral poliovirus infection. Researchers were trying to find new ways to prevent the spread of the virus in countries with poor conditions. In the study, the mice that lacked the interferon receptor gene (IFNAR) and carried the human poliovirus receptor gene were affected by the oral ingestion of poliovirus. Nine days after the ingestion, the mice died and the poliovirus was found in their small intestines and digestive tracts. The mice that expressed the interferon receptor gene (IFNAR) were found to be less affected by the virus. These results show that the interferon receptor gene (IFNAR) is significant in determining how permissive the poliovirus is in the digestive tract as well as the production of virus-specific immune responses to the virus by the oral route. The researchers stated, “Thus, hPVR-Tg/IfnarKO are considered to be the first oral infection model for poliovirus.”

Researchers Use Poliovirus to Destroy Neuroblastoma in Mice

Researchers from Stony Brook University reported that a innocuous form of poliovirus can destroy neuroblastoma tumors in vaccinated mice. Poliovirus kills the host cell it infects so that it can make copies of itself. The researchers injected a weak strain of poliovirus into neuroblastoma tumors that have been transplanted into 12 mice. The poliovirus destroyed the neuroblastoma tumors in all the mice, but tumors reappeared in two mice at the end of the experimental period. The researchers also found out that the injection of poliovirus inhibited new tumor growth in mice. This was important because new growth is common in neuroblastoma even after chemotherapy.

References