Viral Structure |
- The polio virus is made up of an RNA genome and a capsid. The virus is single-stranded.
- The polio virus binds to the immunoglobulin receptor CD155 on the cell surface. This binding causes a confirmational change to occur which enables the virus to enter the host cell. This entry either occurs by the formation of a pore or by receptor-mediated endocytosis. The viral RNA is released immediately after it enters the cell and it takes over the cell's translating mechanisms so that more viral proteins will be produced.
- There are 3 serotypes (variations) of the polio virus. PV1, PV2, and PV3 each have a different capsid protein. Capsid proteins hold the RNA together, help determine the shape of the protein, and determine receptor specificity. PV2 is thought to have been eradicated as it hasn't been documented since 1999 in India and PV3 hasn't been documented since 2012.
- People that are immune to the polio virus (because of the vaccine or because they have already had the infection) have antibodies that prevent the polio virus from replicating. These IgA antibodies are present in the tonsils and in the gastrointestinal tracts. IgM and IgG antibodies are present to keep the virus from spreading to the central nervous system.
Sources:
- http://www.merckmanuals.com/professional/infectious_diseases/enteroviruses/poliomyelitis.html
- http://www.polioeradication.org/Polioandprevention/Thevirus.aspx
- http://en.wikipedia.org/wiki/Poliovirus