34a - Poliovirus Flashcards
What family is poliovirus part of? Genus?
picornaviridae is the family. Fenus enterovirus
Characteristics of poliovirus?
nonenveloped icosahedral capsid, ss positive sense RNA.
What is the reservoir for poliovirus?
humans are only rservoir. spread fecal-oral route.
most common in summer months
How long is incubation period after infection? Where does initial infection occur?
7-14 days after initial replication in lymphoid tissue of pharynx and gut. Secondary spread to viremia and CNS.
What is most common clinical presentation of polio?
subclinical with no signs. (90%)
What are the three types of disease caused by polio
abortive polimyelitis aseptic meningitis (nonparylitic) paralytic poliomyelitis (risk increases with age)
What is post-polio syndorme?
increased weakening of muscles later in life
how is polio diagnosed?
neutralization assays of stool, throat, CSF. (vaccine can be distinguished from wild virus)
How is polio virus best inactivated and killed on surfaces?
resistant to ethanol AND detergents so formaldehyde or chlorine must be used.
What was used by SALK to inactivate polio for the vaccine?
formalin
What are the disadvantages of the Salk vaccine?
requires four subcu injecitons and does NOT prevent wild virus spread, only protects against paralysis
What is the Sabin live OPV?
oral administration of three drops (cheap). but can revert to virulence during preparation or during shedding by recipients.
