Poxviridae Viruses and Diseases

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Questions and Answers

What is a characteristic feature of variola virus?

It produces 'pocks' (correct)

It has a wide host range

It causes tissue hyperplasia

It is transmitted by respiratory route

What is the significance of Edward Jenner's work?

He discovered the myxoma virus

He developed a vaccine for sheeppox

He used a poxvirus of cattle as vaccine for smallpox (correct)

He proved that rabbit fibroma virus causes tissue hyperplasia

How are sheeppox, swinepox, fowlpox, and myxomatosis typically transmitted?

Mechanically by biting arthropods (correct)

Through respiratory route

Through contaminated environment

Through direct contact

What is a common feature of poxviruses?

They have a narrow host range Signup and view all the answers

What is the current status of smallpox?

It has been eradicated Signup and view all the answers

What was the first viral laboratory pathogen described?

Myxoma virus Signup and view all the answers

How is orf virus typically transmitted?

Via respiratory route Signup and view all the answers

What is a unique feature of rabbit fibroma virus?

It causes tissue hyperplasia Signup and view all the answers

What is the typical shape of most poxviruses?

Brick shape Signup and view all the answers

What is unique about the surface structure of Parapoxvirus?

Thread-like surface tubules arranged in a crisscross fashion Signup and view all the answers

Why may the outer tubular layer of some poxviruses appear irregular?

Due to dehydration Signup and view all the answers

What can poxviruses survive in for many years?

Dried scabs or other virus-laden material Signup and view all the answers

What is the size of the brick-shaped poxviruses?

250 x 200 x 200 nm Signup and view all the answers

What is the shape of the nucleocapsid of poxviruses?

Complex Signup and view all the answers

What is unique about the outer layer of poxviruses?

It is composed of an outer layer of tubular structures Signup and view all the answers

Which of the following is a characteristic of Parapoxvirus?

Cocoon (ovoid) shape and irregular surface tubules Signup and view all the answers

What is a characteristic of enveloped virions compared to non-enveloped virions?

They are more readily taken up by cells Signup and view all the answers

Where do poxvirus genome replication and maturation occur?

In enucleated cells, but maturation is blocked Signup and view all the answers

What is the classification of poxviruses that infect vertebrates?

Chordopoxvirinae Signup and view all the answers

What is the economic impact of sheep pox and goat pox?

High mortality and significant economic loss Signup and view all the answers

What is the host range of poxviruses?

Both vertebrates and insects Signup and view all the answers

Which of the following is a poxvirus disease that affects domestic animals?

Sheep pox and goat pox Signup and view all the answers

What is the geographical distribution of swine pox?

Worldwide Signup and view all the answers

Which of the following animals is NOT a host for poxviruses?

Bacteria Signup and view all the answers

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

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Description

This quiz covers the Poxviridae virus family, including diseases of veterinary and medical importance, such as Sheeppox.