Pathophysiology - Infection
- Poliovirus enters the body by the oral fecal route and attaches to the CD155 receptor on the epithelial cells of the lining of the intestine, in particular M-cells (micro-fold cells).
- Once it binds to the CD155 receptor the capsid (it’s protective shell) degrades in the area attached and allows the RNA of the virus to enter into the epithelial cell.
- When it enters the cell it begins to replicate using the cells own ribosomes (the cells protein assembly station) to replicate all of it’s component proteins.
- The components come together and reform within the cell making a new virus RNA and a new capsid, essentially creating new poliovirus which then causes infected cells to swell and burst, thus releasing new poliovirus to infect more cells.
- This process continues till it gets into the bloodstream, where it is transported around and comes into contact with the lymph and muscles.
- If it stops here than only non-paralytic polio is what is present, however, if it goes further and enters the neurons it can cause paralytic polio. This is rare, and it is unclear as to exactly how it ends up in motor neurons, but it does, and the motor neurons have lots of CD155 receptors for it to bind too. So poliovirus in motor neurons replicating and destroying just as it does within the blood until the bodies defenses stop it, or fail entirly, resulting in death.