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[Y2] Infectious Diseases > [W7] Picornaviruses > Flashcards

[W7] Picornaviruses Flashcards

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1
Q

What is the genome type of Picornaviridae?

A

Single-stranded positive-sense RNA

This type of RNA can be directly translated into proteins by the host cell.

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2
Q

Are picornaviruses enveloped?

A

No, they are non-enveloped

Non-enveloped viruses are generally more resistant to environmental conditions.

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3
Q

What is the shape and symmetry of picornavirus capsids?

A

Icosahedral symmetry

This geometric shape is common in many viruses and provides structural stability.

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4
Q

What is the size range of picornaviruses?

A

About 22–30 nm in diameter

This small size allows them to infect host cells easily.

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5
Q

Where do picornaviruses replicate in the cell?

A

In the cytoplasm

This is where the viral RNA can be translated and replicated.

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6
Q

What is the role of VPg in picornavirus RNA?

A

It’s a viral protein linked to the 5’ end of the genome, involved in replication

VPg helps initiate the synthesis of viral RNA.

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7
Q

What does the polyprotein of picornaviruses get processed into?

A

Structural proteins (VP1–VP4) and non-structural proteins for replication

This processing is crucial for the formation of viral components.

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8
Q

What does the picornavirus genome encode?

A

A single large polyprotein

This polyprotein is subsequently cleaved into functional proteins.

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9
Q

How is the polyprotein cleaved?

A

By viral proteases (e.g., 2A, 3C)

These proteases are essential for the maturation of the virus.

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10
Q

What is the role of the IRES in picornaviruses?

A

It enables cap-independent translation of the viral RNA

This allows the virus to hijack the host’s translational machinery effectively.

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11
Q

What does 3Dpol do in the viral life cycle?

A

It is the RNA-dependent RNA polymerase responsible for genome replication

This enzyme synthesizes new viral RNA genomes.

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12
Q

Name four major genera in the Picornaviridae family.

A

Enterovirus, Rhinovirus, Hepatovirus, Aphthovirus

Each genus is associated with different diseases.

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13
Q

Which virus causes poliomyelitis?

A

Poliovirus (a type of Enterovirus)

Poliovirus is notorious for its impact on motor neuron function.

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14
Q

What virus is the most common cause of the common cold?

A

Rhinovirus

Rhinoviruses thrive in the upper respiratory tract.

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15
Q

Which picornavirus causes hepatitis A?

A

Hepatitis A virus (HAV)

HAV is transmitted via the fecal-oral route.

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16
Q

Which picornavirus causes foot-and-mouth disease in livestock?

A

Aphthovirus

This virus affects cloven-hoofed animals and has significant agricultural implications.

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17
Q

How are enteroviruses typically transmitted?

A

Fecal-oral route

This route is common for many gastrointestinal viruses.

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18
Q

What is the primary transmission route for rhinoviruses?

A

Respiratory droplets

This facilitates rapid spread in crowded environments.

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19
Q

Which cells do enteroviruses initially infect?

A

Mucosal and lymphoid tissues of the oropharynx and gut

Initial infection sites are critical for viral dissemination.

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20
Q

How does poliovirus reach the CNS?

A

Through viremia and possible retrograde axonal transport

This ability to invade the nervous system is key to its pathogenicity.

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21
Q

What diagnostic method is commonly used for picornavirus RNA detection?

A

RT-PCR

This technique amplifies viral RNA for detection.

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22
Q

What type of cell culture may be used to isolate poliovirus?

A

HeLa or Vero cells

These cell lines are permissive for poliovirus replication.

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23
Q

What technique confirms serotype in enterovirus infections?

A

Neutralization assay

This assay identifies specific viral strains based on antibody interactions.

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24
Q

What are the two types of polio vaccines?

A

Inactivated (IPV) and oral live-attenuated (OPV) vaccines

Both vaccines play crucial roles in polio eradication efforts.

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25
Is there a vaccine for hepatitis A?
Yes, an inactivated virus vaccine ## Footnote Vaccination is key for hepatitis A prevention.
26
Are there antiviral treatments for most picornaviruses?
No, treatment is mainly supportive ## Footnote Management focuses on alleviating symptoms rather than targeting the virus.
27
What hygiene measure helps prevent enterovirus and HAV transmission?
Handwashing and sanitation ## Footnote These practices are essential for reducing infection rates.
28
What is the function of the 5′ UTR in picornavirus genomes?
Contains the IRES for translation initiation ## Footnote The IRES is crucial for the virus to initiate translation without a 5' cap.
29
What part of the genome encodes structural proteins?
The P1 region ## Footnote This region is essential for building the viral capsid.
30
What are the roles of the P2 and P3 regions?
Encode non-structural proteins for replication and polyprotein processing ## Footnote These proteins are vital for viral life cycle progression.
31
Which viral protein is responsible for RNA synthesis?
3Dpol ## Footnote This polymerase is crucial for replicating the viral genome.
32
What viral protease cleaves host translation factors?
2A protease ## Footnote This cleavage inhibits host protein synthesis, favoring viral replication.
33
How do picornaviruses enter host cells?
By receptor-mediated endocytosis ## Footnote This method allows the virus to exploit host cell receptors for entry.
34
What happens after the picornavirus uncoats?
The viral RNA is released into the cytoplasm for translation ## Footnote Uncoating is a critical step for initiating the viral replication cycle.
35
What is synthesized first upon uncoating?
The viral polyprotein ## Footnote This polyprotein is later cleaved into functional viral proteins.
36
What is the role of 2B and 2C proteins?
They are involved in membrane rearrangement and RNA replication complex formation ## Footnote These proteins help create the environment necessary for viral replication.
37
What viral structure facilitates RNA synthesis on host membranes?
Replication complexes associated with intracellular membranes ## Footnote These structures optimize the replication process.
38
What is the function of VPg during replication?
Serves as a primer for RNA synthesis ## Footnote This function is critical for initiating the synthesis of viral RNA.
39
What is the first step in genome replication after translation?
Synthesis of a complementary negative-strand RNA ## Footnote This step is essential for producing new viral genomes.
40
What property of picornaviruses allows acid stability in some types?
Specific capsid structures in enteroviruses ## Footnote These structures help enteroviruses survive harsh gastrointestinal conditions.
41
Which genus of picornavirus is acid-labile?
Rhinoviruses ## Footnote Their sensitivity to acid limits their ability to survive in the gastrointestinal tract.
42
Why are rhinoviruses not found in the gastrointestinal tract?
They are acid-sensitive and inactivated by stomach acid ## Footnote This acid sensitivity restricts their environmental range.
43
What property makes enteroviruses stable in the GI tract?
Acid stability ## Footnote This property allows them to persist through the digestive system.
44
What does a cytopathic effect (CPE) indicate in cultured cells?
Active viral replication ## Footnote CPE can be observed as changes in cell morphology or behavior.
45
What is VP1 involved in?
Receptor binding and uncoating ## Footnote VP1 is crucial for initiating the infection process.
46
Which structural protein forms the inner surface of the capsid?
VP4 ## Footnote This protein plays a structural role in maintaining capsid integrity.
47
Which protease is responsible for most of the polyprotein cleavage?
3C protease ## Footnote This protease is essential for producing functional viral proteins.
48
What is the function of 3A protein?
Inhibits host protein trafficking and contributes to membrane remodeling ## Footnote This inhibition aids in the virus's replication strategy.
49
What does 3B (VPg) do?
Acts as a primer during RNA replication ## Footnote This function is vital for synthesizing new viral RNA.
50
Why is the IRES important for picornaviruses?
It allows translation initiation in a cap-independent manner ## Footnote This mechanism is crucial for viral survival in host cells.
51
How do picornaviruses shut down host protein synthesis?
By cleaving eIF4G, a translation initiation factor ## Footnote This cleavage prevents the host from producing its own proteins.
52
What host machinery does picornavirus translation bypass?
The cap-binding complex (eIF4E) ## Footnote This bypass allows the virus to efficiently exploit the host's translational resources.
53
What part of the genome contains the IRES?
The 5′ untranslated region (5′ UTR) ## Footnote The 5' UTR is critical for initiating the translation process.
54
How are picornaviruses classified into different serotypes?
Based on differences in capsid proteins, especially VP1 ## Footnote Serotype classification is important for understanding viral diversity.
55
What characteristic allows polioviruses to be differentiated from each other?
Antigenic variation in capsid proteins ## Footnote This variation is significant for vaccine development and epidemiology.
56
Why is genetic variation high in picornaviruses?
Due to error-prone RNA-dependent RNA polymerase (3Dpol) ## Footnote This high mutation rate contributes to the adaptability of picornaviruses.
57
What is a key determinant of neurovirulence in poliovirus?
Ability to infect motor neurons in the spinal cord ## Footnote This characteristic is critical for the severe effects of poliovirus.
58
How does hepatitis A virus avoid causing chronic infection?
It does not integrate into the host genome and is cleared by the immune system ## Footnote This mechanism helps prevent long-term infection.
59
What is unique about rhinovirus growth temperature?
It replicates best at 33°C, the temperature of the upper respiratory tract ## Footnote This temperature preference helps it thrive in its natural environment.
60
Which picornavirus causes myocarditis and pericarditis?
Coxsackie B virus ## Footnote This virus is known for its impact on heart tissue.

[Y2] Infectious Diseases (12 decks)

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