picornaviruses Flashcards
(41 cards)
picornavirus structure
nonenveloped, icosahedral positive sense ssRNA
List the viruses of the picornavirus group and dz they cause
PEERCH: poliovirus, echovirus (aseptic meningitis, hepatitis), enterovirus (respiratory), rhinovirus (cold), coxsackivirus (hand, foot and mouth dz, aseptic meningitis, myocarditis, pericarditis, herpangina), hepatitis A virus.
members of the enterovirus genus
enterovirus is a genus of the picornavirus family. It includes polio, coxsackie, echovirus, enterovirus
What molecules of the virus and the host define picornavirus serotypes?
Neutralizing antibodies from the host and antigenic epitopes of capsid proteins (on the surface of virus particles)
What is the Most Common Respiratory Virus Causing Infection among Patients of All Ages Hospitalized with Acute Respiratory Illness
picornaviruses- cause 25%
enterovirus 68
Most common enterovirus infection in the US in 2014. Causes mild to severe respiratory infections and in rare casses is associated with acute flaccid myelitis/ paralysis and brainstem/ grey matter spinal cord lesions
seasonal incidence of enterovirus
peaks in late summer August-September
Sx of aseptic meningitis
Acute onset of fever, chills, headache, photophobia, and pain on eye movement. Nausea and vomiting are also common. Headaches commonly persist for several days. Patients often describe the headaches as the worst they have ever experienced. Examination reveals meningismus without localizing neurologic signs. CT scans, when performed, are unremarkable
list causes of meningitis in newborn (0-6mos)
Group B strep, e coli, listeria
list causes of meningitis in children (6mos-6years)
S. pneumoniae, N. meningitidis, H flu type B, enterovirus
list causes of meningitis in 6-60yrs
N. meningitidis, enterovirus, S. pneumonia, HSV
list causes of meningitis in 60+ year olds
S. pneumoniae, gram negative rods, listeria
List causes of meningitis in HIV
cryptococcus, CMV, toxoplasmosis, JC virus
compare CSF findings in bacterial, viral and fungal meningitis
bacterial: increased pressure, PMNs, increased protein, decreased sugar. Viral: nl/ elevated pressure, lymphocytes, nl protein and nl sugar. Fungal: increased pressure, lymphocytes, increased protein, decreased sugar
Which picornavirus is associated with myocarditis
coxsackivirus B- occurs in newborns, adolescent or young adults. 10% progress to chronic dilated cardiomyopathy
Hand foot and mouth disease
young children with with fever, anorexia, and malaise followed by the development of sore throat and vesicles on the hands, feet and mouth. Highly contagious. Usually caused by coxsackievirus A16 or enterovirus 71
Picornavirus associated with hemorrhagic conjunctivitis
enterovirus 70 and coxsackievirus A24.
picornavirus penetration into host
Pentamer Extrusion Model: The genomic RNA is extruded from the virion particle into the host cell cytoplasm; through the cell membrane
picornavirus RNA replication
occurs in cytoplasm. Positive sense ssRNA is copied into negative strand RNA by RNA-dependent RNA polymerase, forming a dsRNA intermediate called a replicative intermediate. Negative strand RNA is then copied to make more positive strand RNA.
does picornavirus have replication proteins
NO- virion particles do not contain replicase (RNA dependent RNA polymerase, RNA helicase, capping enzymes)
picornavirus transcription/ translation
the positive sense RNA is used directly as mRNA for translation
picornavirus protein synthesis
After translation of a single polypeptide, it is cleaved into functional viral proteins by viral proteases. Proteins include VP1-4, 2Apro (protease), 3Cpro (protease). Occurs in cytoplasm
Why are most picornavirus infections innocuous
the patient’s acquired immune response typically produces serotype-specific neutralizing antibodies before the virus spreads from mucosal portals of entry to critical target organs
picornavirus pathogenesis
Infection at mucosal surface > viremia to lymph nodes and peripheral tissues > Interferon production limits initial viral replication > secondary viremia (5-15 days later) spreads virus to target organs > IgM and IgG neutralize virus
