Poxviridae

Question 1

Describe Poxviridae characteristics

Answer 1

• ds DNA
• Enveloped – some double enveloped
• caspid = brick /ovoid shaped
- contain genome & lateral bodies
• replicates in cytoplasm
• release budding
• > 100 protein detected in virus-infected cells
- 10 major antigens
- common Nucleoprotein Ag –> cross reactivity
• Virus remains viable in scabs for long pds
• survive years in dust

• Poxvirus in most species except dogs!

Question 2

Where does the Poxvirus replicate

Answer 2

Infect epidermis –> focal lesions –> proliferative –> necrotic

• papule, vesicle, pustule, and finally scabs or crusts
• cultivated in chorioallantoic membrane of chick embryos –> focal lesions = “pocks”

Question 3

If you recover from Poxvirus, can you get it again?

Answer 3

No, life long immunity

Question 4

What oncogenic process has poxvirus been assoc’d w/?

Answer 4

Epidermal & fibromatous hyperplasia

Question 5

Variolation

Answer 5

intranasal insufflation of dried small pox scabs

• 1-2% fatality rate vs 20-30% fatality rate of natural infections

Question 6

Important factors of smallpox eradication program

Answer 6

• Adequate Amt of potent & stable freeze-dried vx
• Single serotype
• Single host
• natural infection –> life-long immunity

Question 7

What is vaccinia virus vaccine?

Answer 7

• Papule appeared at vx site 4-5 d after
–> vesicle –> pustule –> enlarged regional LN
• Pustule dried from center outward 3 wks later
–> scar

Question 8

What makes pox viruses good vx vectors?

Answer 8

• Easy construction
• Relatively high protein expression
• Lg capacity for DNA insertion
• Wide host range

Examples of recombinant vectors
• Canarypox-based vaccine
     • rabies & rinderpest
• Fowl-pox
• Capri-pox
• raccoon-pox

Question 9

Pox virus infecting smal ruminants (SHEEP/GOAT)?

Answer 9

Contagious Ecthyma virus
• Parapoxvirus
• 6 serotypes
• similar to pseudo-cowpox

• Dermatotrophic

Question 10

Is CEV, in sheep/goat, zoonoic?

Answer 10

• Lesions usually confined to hands & face of Human

Question 11

What age group is most susceptible to Contagious Ecthyma virus (CEV)?

Answer 11

Kids & lambs

• -most adults are immune due to vx or prior exposure
• • Ewe nursing infected lamb –> develop lesion on udder

Question 12

Describe the CEV lesion

Answer 12

• Sheep - lips and mouth
• Initial lesion – @ oral mucocutaneous jxn
-spread over face, possibly GI tract or respiratory tract

• Papule –> pustules –> coalesce –> thick tenacious scabs over raise site of inflammation

• morbidity 90&
• mortalitty = low

Question 13

How are sheep vx’d against Contagious Erythema virus (CEV)?

Answer 13

• Scarification (make incision) inner thigh –> brush virus vx
• separate vx’d from non-vx until scabs fall off
• 2nd vx - 2-3mo later

Question 14

What virus causes Orf?

Answer 14

Contagious Ecthyma virus (CEV)

AKA
• contagious pustular dermatitis
• sore mouth

Question 15

What is a parapoxvirus

Answer 15

Contagious ecthyma virus

Question 16

What is an orthopoxvirus

Answer 16

Monkeypox

Question 17

What animals can transmit Monkeypox to humans?

Answer 17

• Pet prairie dogs
• Rodents –> captive cynomologous & rhesus monkeys

• Resembles smallpox 
      - vx --> attenuates dz (85%)
• potentially fatal
• 12d incubation pd
• children most susceptible

Question 18

Describe the structure of Monkeypox virus

Answer 18

• Brick-shaped w/ distinct Dumb-bell lateral core
• single Linear dsDNA virus
     - inverted terminal repeats
     - hairpin loop at each end
• Cytoplasmic replication
• Enveloped OR non-enveloped
     - both infective!

Question 19

How are the lesions of monkeypox and smallpox diff?

Answer 19

• both deep

• monkeypox pitting can resolve
• smallpox pitting = no recovery

Question 20

How can Dx of monkeypox be confirmed?

Answer 20

Electron microscopy exam of vesicle fluid & tissue

Question 21

What should you do if you dx a case of monkeypox?

Answer 21

Report to state & local health dept