Polio virus

Poliovirus is a member of the family Picornaviridae and the causative agent of poliomyelitis, a highly infectious and sometimes debilitating disease. The virus is composed of an RNA genome and a protein shell or capsid. It is one of the most well-studied viruses, with significant contributions to the fields of virology and molecular biology.

Structure and Genome

The poliovirus is an icosahedral virus of approximately 30 nm in diameter. The virus's capsid is composed of 60 copies each of four different viral proteins, VP1, VP2, VP3, and VP4. The RNA genome is a single-stranded, positive-sense RNA molecule approximately 7500 nucleotides long. It is enclosed within the capsid and is directly involved in protein synthesis after the virus infects a host cell.

Life Cycle

The life cycle of the poliovirus begins when it attaches to a receptor on the surface of a host cell. The virus is then taken into the cell where it uncoats and releases its RNA genome. The RNA is translated into a single large protein that is subsequently cleaved into smaller functional proteins. New virus particles are assembled and released from the cell to infect other cells.

Pathogenesis and Disease

Poliovirus primarily infects the cells of the gastrointestinal tract, but can spread to the central nervous system where it can cause paralysis. The severity of the disease can range from asymptomatic infection to severe paralysis and death. The virus is transmitted primarily through the fecal-oral route, but can also be spread through respiratory droplets.

Prevention and Treatment

There is no cure for poliomyelitis, but it can be prevented through vaccination. Two types of vaccines are available: the inactivated poliovirus vaccine (IPV) and the oral poliovirus vaccine (OPV). Both vaccines have been instrumental in the global effort to eradicate polio.

See Also

• Poliomyelitis
• Picornaviridae
• Virology
• Molecular biology
• Vaccine