Picornivirus Diseases Flashcards
Give a rundown on Picrornaviruses.
- Small (they are pico)
- Positive-sense, ssRNA
- Naked
- Icosahedral
How do Picornaviruses infect humans?
Fecal-oral transmission (except Rhinovirus, which is acid-labile)
Enteroviruses are broken down into subtypes not mentioned by Sketchy. Give the categories and examples of each.
- Enterovirus A: Coxsackie A
- Enterovirus B: Coxsackie B
- Enterovirus C: Polio
What is the utility of the subcategorization of the enteroviruses?
The viruses in each category can recombine and make chimeric genomes.
Antibodies to what portion of the Picornavirus virion confers host immunity?
Capsid proteins
Enterovirus D68 caused a fleeting outbreak of _____________ in 2014 and then quickly waned.
flaccid encephalitis
Sketchy does not have a separate video for which Enterovirus?
Echovirus (remember the echoing birds in the top of the aviary)
In general, Enterovirus typically causes disease in which season?
Late summer and early fall
The Picornaviruses can infect ______________.
any tissue of the body
Why is it that the encapsulated bacteria and Enterovirus become the most common causes of meningitis in children 6 months to 6 years?
Maternal antibodies persist for the first six months of life and prevent infection with these organisms.
How do Picornaviruses replicate?
They are positive-sense, ssRNA that directly encodes a polyprotein that contains the capsid protein and replicase proteins.
Which protein makes positive-sense RNA from negative-sense RNA?
RNA-dependent RNA polymerase (RDRP)
Describe the overall pathogenesis of Picornaviruses.
1) Typically, the primary infection is the GI or respiratory mucosa.
2) Viremia leads to the infection of target organs.
3) IgG will lead to future immunity, but IgA is needed to prevent future infection.
Almost all Poliovirus infections are _________________.
asymptomatic (95%)
People infected with Polio become infectious _________________ after being infected themselves.
almost immediately
How does Polio infect the CNS?
It can infect lymphocytes which can cross the BBB (which produces bilateral paralysis), or it can infect motor neurons at the NMJ (asymmetric paralysis).
What are the benefits of Sabin’s attenuated vaccine?
It is inexpensive and induces both IgA and IgG immunity.
Why did the oral polio vaccine regimen lead to infections in the community?
The live virus had attenuating mutations. In the body, mutations occurred that reverted the attenuated virus to live virus in two days.
What Enterovirus was discovered in 2014 at Children’s Hospital Colorado?
Enterovirus 68 (which causes acute flaccid paralysis)
Introduction of a vaccine in 2000 led to a drop from 100,000 cases per year to 10,000 cases per year in _____.
HAV
Polio binds to which receptor?
CD155
Picornavirus virions do not have ___________ proteins.
replicase (thus, RDRP is the first protein that Picornaviruses translate)
Briefly explain how Picornaviruses replicate.
They use ribosomes to make RNA-dependent RNA polymerase. Then, the RDRP makes (-) RNA which is used as a template to make more (+) RNA –also done by RDRP.
Explain why paralytic polio emerged relatively recently.
Polio usually causes paralysis only in adults. Prior to a couple hundred years ago, poor sanitation standards led to widespread polio infection of young children. Because young children are less likely to get paralytic polio, paralytic polio was uncommon until better sanitation practices meant that
_______________ can cause hemorrhagic gastroenteritisi in newborns.
Echovirus
From the time of ingestion onward, how quickly does polio infect the CNS?
Two weeks