Picornaviridae Flashcards
1
Q
Picornoviridae characteristics
A
• Smallest RNA viruses (ss)
• icosahedral
• no envelope
• 5' end
-- virus encoded protein called VPg or 3B
--Internal ribosomal entry site (IRES) ** unique to picorna
• Rapidly cytopathic in cell culture
• Typically host specific
• resistant to many disinfectants
2
Q
What is the fxn of IRES
A
enhance ribosomal recognition of the virus RNA facilitating translation of viral proteins
3
Q
Picornavirus that occurs in swine
A
- Foot & mouth dz
(Aphthovirus)
– also ruminants - Swine vesicular dz
(Enterovirus)
4
Q
Swine vesicular disease virus
A
• infects swine & humans
- influenza-like signs
• Trasmission = ingestion
- contaminated garbage
- undercooked meat (salami)
• 2-4 day incubation
Clinical signs
• Vesicles at coronary band & interdigital spaces, mouth, snout
No vx recommended
5
Q
Foot and Mouth disease virus
A
- Highly infectious (cloven-hoofed)
- Systemic dz
- high fever
- vesicles on epithelial surfaces
- Fatal in young (myocarditis)
- non-fatal in adults –> economic loss
- Virus shed in mucosal secretions, milk, urine, feces
- 2-8 day incubation
6
Q
What countries are FMD-free?
A
North america & New Zealand
7
Q
What can be used to inactivate FMDV?
A
- 5% acetic acid
- 1-2% sodium hydroxide
- Oxidizing agents (bleach) if no organic matter
- Heat
8
Q
Describe the diff effects on susceptible hosts:
• Pigs
• Cattle
• Sheep
A
Pigs
- Amplifying Host
- secrete Lg ants of virus in breath
- airborne
Cattle
- Sentinel Host
- highly sensitive to infection by respiratory route
Sheep
- Maintenance Host
- Mild to asymptomatic dz
9
Q
Factors that allow rapid spread & persistence of FMD
A
- Ag variation
- Lg host range
- Low infectious dose
- Lg Amt of virus before clinical signs develop
- not all species have clinical signs
- persistent infection in partially immune
- Many rounds of transmission (hardy)
