The Polio-virus, also known as Poliomyelitis, is a disease that attacks the body and can leave the victim permanently damaged or even dead.
Viral Structure
|
Poliovirus is a small and simple virus.
The poliovirus capsid is around 30 nanometers in diameter. In the capsid is the information that it needs to make new virus particles – a single molecule of ribonucleic acid, or RNA. When the virus infects a cell, the RNA genome enters the cell and programs it to make new virus particles. These virus particles are released from the cell and go on to infect new cells. In humans, the poliovirus is ingested, and replicates in cells of the gastrointestinal tract. Newly synthesized virus particles are released into the intestine and shed in the feces. After multiplying in the gastrointestinal tract, poliovirus may enter the spinal cord and brain. Destruction of motor neurons by the virus leads to limb paralysis. |
Taxonomy Reproduction
Polio, also known by the scientific name Poliomyelitis, is caused by the virus Poliovirus, which is a highly contagious virus that is specific to humans.The term Poliomyelitis is from the Greek polios, which means gray, and the word meyelos, which means "Inflammation"
Polio is classified as either symptomatic or asymptomatic. Most cases display no symptoms (asymptomatic polio), and a very small amount of the cases display symptoms (symptomatic polio). There are three types 1. Sub-clinical: Approximately 95 percent of polio cases are sub-clinical, and; the form of polio does not affect the central nervous system (the brain and spinal cord). 2. Non-paralytic: This form, which does affect the central nervous system, produces only mild symptoms and does not result in paralysis. 3. Paralytic: The rarest and most serious form of polio; produces full or partial paralysis in the patient. There are three types of paralytic polio Post-Polio syndrome: - a complication that can occur years after a victim is infected with the virus. Symptoms can appear up to thirty years after the infection -Polio Taxonomy: - Group IV ((+)ssRNA - Order: Picornavirales - Family: Picornaviridae -Genus: Enterovirus - Species: Enterovirus C -(Sub group) serotypes: Poliovirus (PV)-1, PV-2, PV-3 |
The steps:
1. initiated by the binding of a poliovirion to the cell surface macromolecule CD155, which functions as the receptor. 2. The uncoating of the viral RNA is mediated by a receptor-dependent destabilization of the virus capsid 3. Cleavage of viral protein VPg is performed by a cellular phosphodiesterase, and the translation of the viral RNA occurs by a cap-independent (IRES-mediated) mechanism 4. The Proteolytic processing of the viral polyprotein yields mature structural and non-structural proteins 5. The positive-sense RNA serves as a template for complementary negative-strand synthesis, producing a double-stranded RNA (replicative form, RF) 6.The initiation of many positive strands from a single negative strand produces the partially single-stranded replicative intermediate (RI). 7. The newly synthesized positive-sense RNA molecules serve as templates for translation or associate with capsid precursors to undergo encapsidation and induce the maturation cleavage of VP0 , 8. It generates progeny virions. The lysis of the infected cell results in release of infectious progeny virions |