Characteristics
What is the primary route of transmission of poliovirus?
Fecal–oral route
Through which route does poliovirus spread to the central nervous system?
Bloodstream (viremia) → CNS
What type of paralysis is associated with poliomyelitis?
acute flaccid paralysis
What are the two main types of polio vaccines?
OPV (oral) and IPV (inactivated)
Which receptor does poliovirus use to enter host cells?
CD155 (poliovirus receptor)
Which cells in the spinal cord are targeted by poliovirus?
Anterior horn cells of spinal cord
What is the difference between abortive and paralytic polio?
Abortive: mild, no CNS involvement; Paralytic: CNS involvement with paralysis
Why is OPV widely used in mass immunization campaigns?
Induces strong intestinal (mucosal) immunity and easy administration
Explain the significance of the VP1 protein in poliovirus infection.
VP1 mediates attachment to CD155 receptor
Explain the steps of poliovirus dissemination from gut to CNS.
Ingestion → gut replication → lymphatics → primary viremia → secondary viremia → CNS invasion
Explain the pathophysiology of flaccid paralysis in poliovirus infection
Destruction of anterior horn motor neurons → loss of muscle innervation
Explain vaccine-derived poliovirus (VDPV).
Mutated vaccine strain regains virulence and spreads
How does poliovirus shut off host cell protein synthesis?
Poliovirus cleaves host eIF4G → inhibits host cap-dependent translation
How does poliovirus evade innate immune responses?
Inhibits interferon response and host protein synthesis
Explain the mechanisms underlying post-polio syndrome decades after infection.
Due to gradual degeneration of enlarged motor units formed after initial recovery
Describe the genetic reversion process in attenuated poliovirus strains
Genetic mutations/recombination restore neurovirulence