17 - Poliovirus Flashcards
In most of the world, poliovirus is mainly a _____________, however, some developing countries are still affected
historical issue
Poliovirus is associated with what type of food products?
milk and milk products
Can poliovirus spread via the fecal oral route from person to person?
YES
Pasteurization of milk at above ___C for ___sec deactivates poliovirus
70
30
What are the 2 vaccines effective at preventing the illness caused by poliovirus
- the inactivated poliovirus vaccine (IPV)
- the oral poliovirus vaccine (OPV)
Poliovirus mainly affects:
children under the age of 5 years old
1 in 200 poliovirus infections leads to _______________
irreversible paralysis
T or F: As long as a single child remains infected, children in all countries are at risk of contracting polio
T
Poliovirus is transmitted via the fecal oral route and multiplies in the __________
intestine
Poliovirus invades the ___________, and can cause total paralysis in a matter of ______.
nervous system
hours
Initial symptoms of poliovirus include:
- fever
- fatigue
- headache
- vomiting
- stiffness of the neck
- pain the limbs
Poliovirus has a:
__________ genome
__________ssRNA
____________ virus with a protein capsid
RNA
+
non-enveloped
What are the 3 serotypes of poliovirus and why are they different:
PV1
PV2
PV3
*they each have a slightly different capsid protein
Capsid proteins define cellular receptor __________ and virus ____________
specificity
antigenicity
T or F: All three serotypes PV1, PV2, PV3 are extremely infectious
T
T or F: PV1 is the most common in nature
T (localized in Pakistan and Afghanistan)
PV2 is likely eradicated, it was last detected in _______
India
T or F: PV3 has not been detected since 2012, so it is likely eradicated
T
The poliovirus genome consists of a single-stranded, positive-sense RNA, which encodes a single ________
polyprotein
The 5’ non-translated region (NTR) harbors two functional domains, the ____________ and the_______________, and is covalently linked to the viral protein ____
cloverleaf
internal ribosome entry site (IRES)
VPg
The 5’ - terminal cloverleaf, helps to regulate viral _____________, as well as initiation of ______________
RNA replication
translation
The IRES mediates translation of viral ______
mRNA
The 3’ NTR is ________________
poly-adenylated
The polyprotein contains N-terminus to ___________, structural ____ and non-structural _____ proteins that are released from the polypeptide chain by _____________ mediated by virally-encoded proteinases
C-terminus
P1
P2-P3
proteolytic processing
The polyprotein ultimately encoded ___ mature viral proteins
11
Poliovirus lifecycle:
- poliovirion binds to the cell surface receptor
- uncoating of the viral RNA
- Cleavage of viral protein VPg is performed by cellular phosphodiesterase
- translation of the viral RNA
- poliovirus mRNA is translated as one long polypeptide
- The positive-sense RNA serves as template for complementary negative-strand synthesis, thereby producing a double-stranded RNA
- associate with capsid precursors to undergo encapsidation
- lysis of the infected cell results in release of infectious progeny virions
Poliovirus assembly:
- P1 precursor is cleaved to yield VP1, VP3, and VP0
- They are assembled into 5S monomers and then into 14S pentamers
- 12 of these pentamers associate directly with genomic RNA being transcribed by membrane-bound complexes to assemble an immature 150S provirion
- VP0 is further cleaved to yield VP2 and VP4 resulting in the mature virion
