24 Questions
What is a characteristic feature of variola virus?
It produces 'pocks'
What is the significance of Edward Jenner's work?
He used a poxvirus of cattle as vaccine for smallpox
How are sheeppox, swinepox, fowlpox, and myxomatosis typically transmitted?
Mechanically by biting arthropods
What is a common feature of poxviruses?
They have a narrow host range
What is the current status of smallpox?
It has been eradicated
What was the first viral laboratory pathogen described?
Myxoma virus
How is orf virus typically transmitted?
Via respiratory route
What is a unique feature of rabbit fibroma virus?
It causes tissue hyperplasia
What is the typical shape of most poxviruses?
Brick shape
What is unique about the surface structure of Parapoxvirus?
Thread-like surface tubules arranged in a crisscross fashion
Why may the outer tubular layer of some poxviruses appear irregular?
Due to dehydration
What can poxviruses survive in for many years?
Dried scabs or other virus-laden material
What is the size of the brick-shaped poxviruses?
250 x 200 x 200 nm
What is the shape of the nucleocapsid of poxviruses?
Complex
What is unique about the outer layer of poxviruses?
It is composed of an outer layer of tubular structures
Which of the following is a characteristic of Parapoxvirus?
Cocoon (ovoid) shape and irregular surface tubules
What is a characteristic of enveloped virions compared to non-enveloped virions?
They are more readily taken up by cells
Where do poxvirus genome replication and maturation occur?
In enucleated cells, but maturation is blocked
What is the classification of poxviruses that infect vertebrates?
Chordopoxvirinae
What is the economic impact of sheep pox and goat pox?
High mortality and significant economic loss
What is the host range of poxviruses?
Both vertebrates and insects
Which of the following is a poxvirus disease that affects domestic animals?
Sheep pox and goat pox
What is the geographical distribution of swine pox?
Worldwide
Which of the following animals is NOT a host for poxviruses?
Bacteria
Study Notes
Poxviridae
- Includes several viruses of veterinary and medical importance
- Poxviruses have been eradicated in developed countries but still occur in some developing countries, causing major losses
- The history of poxviruses has been dominated by smallpox, which has been eradicated
Transmission
- Occurs by several routes through introduction of virus into small skin abrasions or directly or indirectly from a contaminated environment
- Examples:
- Orf virus is transmitted by the respiratory route via droplets from infected animals
- Sheeppox, swinepox, fowlpox, and myxomatosis are transmitted mechanically by biting arthropods
Replication Cycle
- occurs in enucleated cells, but maturation is blocked
- Some contribution from the cell is required, but it is not clear what this is
Classification
- The family Poxviridae is subdivided into two subfamilies:
- Chordopoxvirinae (poxviruses of vertebrates)
- Entomopoxvirinae (poxviruses of insects)
- The subfamily Chordopoxvirinae is subdivided into several genera
- There are other poxviruses that have not yet been classified
Host Range
- Numerous hosts, including:
- Humans
- Cattle
- Rabbits
- Squirrels
- Monkeys
- Great apes
- Elephants
- Rhinoceros
- Okapi
- Gerbils
- Voles
- Seals
- Camels
- Chickens
- Turkeys
- Other birds
Sheep Pox and Goat Pox
- The most important of all pox diseases of domestic animals
- Causes high mortality in young animals and significant economic loss
- Poxviruses are resistant in the environment under ambient temperatures and may survive for many years in dried scabs or other virus-laden material
Virion Properties
- Shape:
- Brick shape (250 x 200 x 200 nm) (most poxviruses)
- Cocoon (ovoid) shape (260 x 160 nm) (Parapoxvirus)
- Nucleocapsid is complex
- Virions are composed of an outer layer of tubular structures
- Outer tubular layer:
- Irregular (most of poxviruses)
- Thread-like surface tubules, arranged in a crisscross fashion (Parapoxvirus)
- Exceptions: some viruses of reptiles are brick-shaped but have a surface structure similar to parapoxviruses
This quiz covers the Poxviridae virus family, including diseases of veterinary and medical importance, such as Sheeppox.
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