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49 Cards in this Set
- Front
- Back
3 main genera within picornaviruses that infect humans
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Enteroviruses
Heparnaviruses Rhinoviruses |
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Poliovirus is part of what genera
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Enterovirus
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Where do they enteroviruses replicate
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GI tract
Transmitted by fecal-oral route NOTE: do NOT cause severe GI disease |
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Where do rhinoviruses replicate
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Nose & upper respiratory tract
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What is the site of recognition of picornaviruses for virus receptors?
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Cleft in VP1 protein
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These picornaviruses are NOT sensitive to acid pH
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Enteroviruses
Includes: poliovirus, coxsackie, echo, entero |
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Capsid proteins are at what end of the picorna RNA
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5' end
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IRES
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Internal Ribosome Entry Site
Serves same purpose as RNA cap, which these do NOT have |
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VPg
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Primer in RNA replication at 5' end
Removed to allow translation to begin |
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Where does picornavirus replication take place?
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ENTIRELY in cytoplasm
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This event transforms procapsid into a mature capsid
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Proteolytic cut in one of the casid proteins
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How long does picornavirus replication cycle take?
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6 - 8 hours
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How do picornaviruses overhaul cellular machinery?
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Cleave and inactivate host protein that recognizes mRNA "cap"
Stops host cell synthesis BUT, viral synthesis can continue due to IRES |
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What type of paralysis does polio cause?
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Flaccid
From destruction of motor neurons |
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Which polio serotype causes most paralysis?
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Serotype 1
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How does poliovirus spread in the body?
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Hematogenously
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How long is the incubation period of poliovirus?
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7 - 14 days
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Abortive polio
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~90% of cases or more
Sore throat or GI symptoms NO neurological problems Resolves in a few days |
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Non-paralytic polio
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5% of cases
Back/Neck pain, muscle spasms Spreads to CNS, but NO paralysis Recovery is complete after 2-10 days |
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Paralytic Poliomyelitis
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~1% of cases
ASYMMETRIC, FLACCID paralysis May be accompanied by meningitis NO SENSORY LOSS Maximal recovery ~6 months Recovery is almost NEVER COMPLETE Recovery results in lifelong immunity |
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Post-polio syndrome
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Muscle wasting and mild paralysis
Can occure 30 - 40 yrs after primary disease NOTE: NO viral growth during this |
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Binding of what can neutralize poliovirus?
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Neutralizing epitopes on VP1
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How long does passive immunity (mom-->kid) last against polio?
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~6 months
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What types of vaccines are available for polio?
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Killed (Salk)
Live attenuated (Sabin) |
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Reservoirs for polio
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HUMAN ONLY
BUT, can be transferred to monkeys |
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Seasonality of polio
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Temperate climate -- summer/early fall
Tropics -- all year long |
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Age group most at risk for polio
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5 - 15 yr. olds
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Type A coxsackie only are most usually found in what diseases?
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Herpangina
Hand-foot-mouth Acute hemorrhagic conjuctivitis Think face/mouth |
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Type B coxsackie only are most usually found in what diseases?
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Pleurodynia
Myocarditis Meningoencephalitis Think heart/chest/brain |
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When are coxsackie virus infections most common?
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Summer
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How do coxsackie viruses spread within body?
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Hematogenously
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How long is the incubation period for coxsackie viruses?
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2 - 9 days
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Herpangina
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Severe febrile pharyngitis
Onset is abrupt Only a few days duration (self-limiting) Caused by some GROUP A coxsackie viruses Pharynx has characteristic vesicles on palate Can affect any age group, but children @ highest risk |
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How is Hand-Foot-Mouth disease distinguished from Herpangina
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HFM lesions occur more towards ANTERIOR mouth
Palms and soles are involved in HFM |
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HOw is HFM distinguished from chicken pox
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HFM almost always involves the mouth
Chicken pox makes people more sick |
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Hand-Foot-Mouth Disease (HFM)
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Ulcers in mouth, and vesicular rash on palms/soles
Rash may spread to arms/legs Most common in children Caused by Group A Coxsackie viruses |
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Pleurodynia
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Also called Bornholm's disease
Sudden onset fever and chest & ab pain Pain worsened by movement and breathing Caused by Group B Coxsackie Most common in children Lasts week or so Relapses may occur |
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Coxsackie-related myocarditis is worst in what age group?
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Newborns
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What viruses cause Acute hemorrhagic conjuctivitis
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Enterovirus 70
Coxsackie virus A24 |
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What is incubation period in case of acute hemorrhagic conjuctivitis?
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Very short - 24 hrs.
Cases resolve spontaneously in 1-2 weeks |
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What other infections can coxsackie viruses cause?
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Coxsacikie A alone -- diarrhea
Coxsackie A & B -- common cold |
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Seasonality of common cold
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Early Fall
Late Spring |
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Non-rhinoviruses that cause common cold
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Parainfluenze
Adenoviruses Coronaviruses Enteroviruses |
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What other animals canbe infected with rhinovirus?
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Gibbons
Chimps |
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Conditions that rhinoviruses survive or succumb to
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Inactivated @ acid pH (3)
Replicate best @ 33 degrees C Very stable to dehyrdation |
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Most important methods of rhinovirus transmission
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Self inoculation (fingers, etc.)
Aerosol |
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How long does it take for Ab to show for rhinovirus?
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7 - 21 days
NOTE: this is after disease has cleared (takes 3-7 days) Ab is protective against subsequent infection of SAME serotype |
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Why is rhinovirus vaccine unlikely?
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Poor growth in cell culture
TOO MANY serotypes |
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Which picornavirus does NOT grow well in cell culture?
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Rhinovirus
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