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)
3 countries that still have polio
Afghanistan, Nigeria, Pakistan
Other enteroviruses cause
Exanthems, febrile illness, URI, acute hemorrhagic conjunctivitis
Which virus causes Hand foot and mouth disease
Coxsackie A
Which virus causes overwhelming neonatal disease?
Coxsackie B
How to distinguish viral meningitis from bacterial?
Elevated WBC in CSF, but markedly less than bacteria. Lymphocytic predominance, normal glucose and protein.
Prion diseases
Long incubation period, Slow but progressive neurologic deterioration, uniformly fatal over a period of months
Common pathologic findings in prion diseases
Minimal inflammatory response, neuronal degeneration, astrocyte proliferation, vacuoles within cells,
PrP
Prion protein, conformation isomer of a normal host protein, accumulates in the brain of affected individuals very resistant to chemical or physical inactivation, transmitted by infected brain tissue, transmission can be iatrogenic, can be genetic
