Is there a defense?
Poliovirus is a cytocide agent, which means that it impacts individual cells at a time. Because of this, the most important defense are by antibodies. To get best results, around 200 lymphocytes are necessary. Phagocytes and T lymphocytes are in charge of viral clearance from the central nervous system. Though the immune system might not be able to completely defeat polio, it can at least control it so some extent.