Enteroviruses Flashcards
Picornaviruses
Pico(Small) RNA viruses, enterovirus, rhinovirus, hepatitis A
How many serotypes of enteroviruses are there?
71, polioviruses 1-3, coxsackie viruses, echoviruses, numbered enteroviruses
Enterovirus seasonality
Temperate climates: summer and fall, Tropics: year round.
Who does enterovirus affect most?
Children
What type of symptoms do most enteroviruses cause?
Most are asymptomatic or result in non-febrile illness with mild respiratory symptoms
Enterovirus viral characteristics
+ sense, single stranded RNA viruses, icosahedral capsid, NO envelope but resistant to harsh environmental conditions like sewage, broad pH range, GI tract, detergents
VP1
Contains receptor binding site that is buried within a canyon to hide it from antibodies
Enterovirus replication cycle
Reception, internalization, replication in cytoplasm, inhibition of host cell RNA synthesis, cytolytic
Pathogenesis of poliovirus
Enters the nasopharynx, replicates in oropharynx, primary virema, travels via nerves from muscle to motor neurons in anterior horn and brainstem, shedding in stool
Where can viruses be shed for weeks?
Nasal secretions and stool (longer in stool)
Mechanism of injury for enteroviruses
Cytolysis (for all but Hep A), immune mediated (for Hep A).
What prevents establishment of initial infection
Sec IgA
What prevents/controls viremia?
Serum IgG
What type of clinical syndromes does poliovirus cause?
Asymptomatic in 90%, Minor febrile illness in 5%, non paralytic aseptic meningitis in 1-2 percent, Paralytic in 2% or less.
Two polio vaccines
Inactivated: Salk (IM)
Live: Sabin (oral)
