Microbiology
Summary
Poliovirus, a member of the Picornaviridae family, is a naked, positive-sense RNA virus responsible for causing polio. While the disease has been largely eradicated in many parts of the world, it still persists in regions of Asia and Africa. Poliovirus possesses acid-stable properties, enabling it to endure the acidic environment of the stomach. Its primary transmission and replication occur in lymphoid tissues such as the tonsils and PeyerÕs patches, subsequently moving to the anterior horn of lower motor neuron cell bodies.
The symptoms of polio encompass asymmetric paralysis, typically concentrated in the lower legs, along with myalgias, reduced deep tendon reflexes, respiratory insufficiency due to diaphragm paralysis, and occasionally aseptic meningitis.
While treatment for polio remains unavailable, prevention is achieved through vaccines, including the Salk and Sabin vaccines named after their inventors. The Salk vaccine is an inactivated, or killed, vaccine that generates IgG antibodies, bypassing the GI tract. Conversely, the Sabin vaccine is a live, attenuated vaccine administered orally, triggering the creation of both IgG and IgA antibodies.
Lesson Outline
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FAQs
Poliovirus is a highly infectious virus that primarily targets children. It belongs to Picornaviridae, a family of positive-sense RNA viruses. Poliovirus primarily spreads via the fecal-oral route, mostly affecting the gastrointestinal system, specifically in the Peyer's patches of the small intestine.
Poliovirus is typically transmitted through the fecal-oral route. This means that the virus exits the body in feces, which if not disposed of properly, can contaminate water or food. If another person consumes this contaminated water or food, they can become infected with the virus.
Poliovirus is classified as an acid-stable virus because it has the ability to survive in harsh and acidic environments like the stomach, which gives it an advantage in invading the host body through oral consumption.
The Salk and Sabin vaccines are two types of polio vaccines developed by Jonas Salk and Albert Sabin. The Salk vaccine, introduced in 1955, is an inactivated polio vaccine (IPV) given by injection, which carries dead poliovirus strains. On the other hand, the Sabin vaccine, introduced in 1961, is an oral polio vaccine (OPV) that contains attenuated (weakened) poliovirus and triggers a strong immune response.
Asymmetric paralysis is a condition where one side of the body is more affected than the other. Poliovirus often causes this because the virus tends to infect the motor neurons in the spinal cord unevenly, leading to muscle weakness or paralysis on one side of the body.
