Figure 2. Evolutionary layers of the X and Y chromosomes. (a) Comparative mapping of genes from the human X in marsupial mammals detected an ancient region conserved on the X in all mammals and denoted XCR, as well as a recently added region denoted XAR that is autosomal in marsupials.
Poliovirus, the causative agent of poliomyelitis (commonly known as polio), is a human enterovirus and member of the family of Picornaviridae. Poliovirus is composed of an RNA genome and a protein capsid. The genome is a single-stranded positive-sense RNA genome that is about 7500 nucleotides long.
The polio shot (IPV) does not cause polio The recommended schedule for polio vaccination is three doses of IPV at 2, 4, and 6 months of age, and a booster at 4-6 years of age. Booster doses of polio vaccine are also recommended for persons traveling to areas of the world where polio is still a problem.olio [PO-lee-oh] is a viral disease that can damage the nervous system and cause paralysis. The polio virus enters the body through the mouth, usually from hands contaminated with the stool of an infected person. Polio is preventable by immunization.