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VM639: Virology > Poxviridae (Exam 2) > Flashcards

Poxviridae (Exam 2) Flashcards

1
Q

Define: Variolation

A

Insufflation or scarification using material from smallpox lesions

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2
Q

What is the timeline of vaccination utilizing smallpox?

A

1776: Edward Jenner noted that humans with a previous history of cowpox infection, variolae vaccinae, were protected against smallpox
1798: Jenner used material human “cowpox” lesions to inoculated humans who were then challenged with smallpox
1971: Smallpox eradication from human populations

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3
Q

What vaccine was utilized for smallpox vaccination? Is it still used? Why or why not? Is it the same as the one Jenner used?

A

Vaccinia (origin uncertain)
Not the same virus as Jenner’s orginal vaccine for smallpox
Use has been discontinued (eradication) = complications in patients with eczema, defects of CMI, other varieties of immunosuppression

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4
Q

Where is vaccinia seen today? What animals?

A

Present in Brazil, India, Egypt in Cattle and Buffalo
Useful model for laboratory study of poxviruses
Therapeutics: now used in recombinant DNA vaccines, vectors for delivering antigen, gene therapy

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5
Q

What is the history of exposure for Mpox?

A

Exposure to prairie dogs (traceback to imported African rodents and exposure of prairie dogs, dispersal, and sale

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6
Q

What are the clinical signs of Mpox in humans? What is the incubation period?

A

Rash, fever
Incubation = 12 days

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7
Q

How is Mpox diagnosed?

A

PCR
Virus Isolate
Immunohistochemistry
Electron Micrograph

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8
Q

What are the general characteristics of Poxviridae?

A

Large
Complex
Enveloped
Linear dsDNA genome

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9
Q

Who is affected by Poxviridae?

A

Pathogens of mammals, birds, and insects

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10
Q

What are important aspects of the structure of poxviridae?

A

Dumbbell shaped core containing viral DNA genome and proteins
Complex, oblong shape, >100 viral proteins in virion
Lateral bodies flanking the core contain proteins
Surface tubules
Stable in environment

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11
Q

Where does poxvirus replication occur?

A

In the cytoplasm (unique for DNA viruses - can be demonstrated in enucleated cells)

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12
Q

What enzymes and proteins are included in the poxvirus virion?

A

Transcriptase, DNA polymerase, enzymes needed for genomic DNA synthesis
100 early genes include virokines and growth factors
Late genes encode structural proteins, viral enzymes included in virion

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13
Q

Describe the steps of virion assembly of poxviridae

A

(1) Spherical immature particles
(2) Outer bilayer becomes the outer membrane of the virion
(3) Core and lateral bodied differentiate within the outer membrane
(4) Mature virions can acquire an envelope from the Golgi apparatus and are released by exocytosis
*Some virions are not enveloped and are released by cell lysis

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14
Q

What are the poxvirus virokines?

A

Homologue of epidermal growth factor
Complement (C3b, C4) binding proteins
Interferon resistance
TNF soluble receptor, TNF resistance
CrmA (serpin) inhibits ICE protease and apoptosis
“Viral host response modifiers”

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15
Q

Describe poxvirus IFN resistance

A

Myxomavirus M-T7 is a soluble IFN-gamma receptor
Vaccinia E3L binds dsRNA and blocks activation of Pkr
Vaccinia A18R regulates dsRNA production

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16
Q

What are the clinical signs of poxvirus infections? Which viruses cause which?

A

Localized skin infections resulting in skin lesions (e.g. orf swinepox, swinepox, molluscum contagiosum)
Skin lesions following in systemic infections (ecromelia, smallpox)

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17
Q

How are poxviruses transmitted? Which viruses are associated with each?

A

Mechanical transmission by biting arthropods (fowlpox, sheeppox, myxomavirus)
Introduction into abrasions from fomites or the environment (molluscum contagiosum)
Aerosolized respiratory secretions (smallpox)

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18
Q

What is the progression of pox lesions?

A

Macule
Papule
Vesicle
Pustule
Ulceration
Scab Formation
Healing/Scar

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19
Q

What are examples of Orthopoxviruses?

A

Variola (smallpox)
Vaccinia
Cowpox
Camelpox
Ectromelia
Mpox
Uasin Gishu
Tatera pox
Raccoon pox
Vole pox
Seal pox

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20
Q

What is the etiologic agent of cowpox?

A

Many poxviruses of rodents, (pet) rats, mice, voles, gerbils

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21
Q

What is the host range of cowpox?

A

Natural host are rodents
Diseases occur in domestic/large cats, cows, humans, rhinoceros, elephants

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22
Q

What are the clinical signs of cowpox in different hosts?

A

Cows: lesions on teats
Dogs, Cats: paws, head mouth lesions
Cats: severe disseminated disease
Humans: skin lesions

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23
Q

How is cowpox transmitted?

A

Aerosolized respiratory secretions
Direct contact
Fomites (e.g. milking machines)

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24
Q

How is cowpox shed?

A

Scab material
Aerosol (cats)

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25
Q

How is cowpox prevented?

A

Disinfection of milking equipment
Sanitation
Rodent Control

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26
Q

What poxviruses cause localized infections?

A

Swinepox
Pseudocowpox
Bovine papular stomatitis
Contagion ecthyema, contagios pustular dermatitis, “orf”, “soremouth”
Cowpox in cattle

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27
Q

What is the etiological agent of swinepox?

A

Swinepox virus (uncommon in commercial herds in the US)

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28
Q

What is the host range of swinepox?

A

Suidae
Most severe in pigs <4 months of age

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29
Q

What are the clinical signs of swinepox?

A

“Pox” skin lesions
Fever, vesicles, pustules, scabs

30
Q

How is swinepox transmitted?

A

Mechanical by biting lice, Hematopinus suis

31
Q

How is swinepox prevented?

A

Control of lice, sanitation

32
Q

What are examples of parapoxvirus?

A

Orf virus
Pseudocowpox
Bovine papular stomatitis virus
Ausdyk virus
Seal parapoxvirus

33
Q

What is the etiologic agent of Orf?

A

Contagious ecthyema virus

34
Q

What is the distribution of Orf?

A

Worldwide

35
Q

What is the host range of Orf?

A

Ovidae

36
Q

What are the symptoms of Orf?

A

Papules, pustules, rough raised scabs, lesions on lips, nose, face, feet, teats

37
Q

What is the morbidity/mortality of Orf?

A

High morbidity, low mortality

38
Q

Is Orf zoonotic?

A

Yes
Individual raised proliferative lesions with an umbilicated center and scab formation

39
Q

How is Orf transmitted?

A

Mechanical transfer by direct contact, fomites, thorns

40
Q

How is Orf shed?

A

Scabs (virus is stable)

41
Q

How is Orf prevented?

A

Vaccines, live non-attenutated, short duration of immunity
Stability of the virus in the environment makes it difficult to eradicate from a premise

42
Q

What is the etiologic agent of pseudocowpox?

A

Pseduocowpoxvirus

43
Q

What is the distribution of pseudocowpoxvirus?

A

Worldwide

44
Q

What is the host range of pesudocowpox?

A

Bovidae

45
Q

What are the clinical signs of pseduocowpox?

A

Scabs on teats or in the mouths of calves

46
Q

How is pseudocowpox transmitted?

A

Mechanical transfer by direct contact, fomites, flies

47
Q

How is pseudocowpox shed?

A

Virus present in skin lesions

48
Q

How is pseudocowpox prevented?

A

Disinfection of milking equipment between cows

49
Q

What is the etiological agent of bovine papular stomatitis?

A

Bovine papular stomatitis virus

50
Q

What is the distribution of bovine papular stomatitis?

A

Worldwide

51
Q

What is the host range of bovine papular stomatitis?

A

Bovidae

52
Q

What are the clinical signs of bovine papular stomatitis?

A

Raised circular lesions in the mouths of calves
Usually of little clinical importance
Occasional spread to skin

53
Q

How is bovine papular stomatitis transmitted?

A

Direct contact
Fomites

54
Q

How is bovine papular stomatitis shed?

A

Virus present in lesions

55
Q

How is bovine papular stomatitis prevented?

A

Disinfection of bottles, pails
Prevent contact with infected calves

56
Q

What is the etiological agent of avipox?

A

Multiple avian poxviruses

57
Q

What is the host range of avipox?

A

Many wild and domestic birds

58
Q

What are the 2 forms of the disease cause by avipox? What are the lesions associated with each?

A

Cutaneous (Dry): “pox” lesions on eyelids, mouth, feet, comb
Diptheritic (Wet): lesions in the mouth, pharynx, trachea

59
Q

How is avipox transmitted?

A

Mechanical by arthropods, abrasions, wounds
Aerosolized droplets

60
Q

How is avipox prevented?

A

Vaccination
Insect control
Sanitation

61
Q

What is the etiologic diagnosis of sheeppox/goatpox?

A

Genetically similar viruses, sheeppox, goatpox, lumpy skin disease virus

62
Q

What is the distribution of sheeppox/goatpox?

A

Asia and Africa
Exotic to the US

63
Q

What is the host range of sheeppox/goatpox?

A

Sheep, goats, cattle

64
Q

What disease is associated with sheeppox/goatpox?

A

Pox lesions on skin, extensive distribution

65
Q

What is the mortality rate of sheeppox/goatpox in young animals?

A

High
50-100%

66
Q

How is sheeppox/goatpox transmitted?

A

Mechanical via wounds, biting arthropods
Aerosolized respiratory secretions during outbreaks

67
Q

What is lumpy skin disease?

A

Systemic spread of sheeppox/goatpox
Scabs contain infectious virus, durable in the environment

68
Q

What is the etiologic agent of myxomatosis?

A

Myxoma virus

69
Q

What is the host range of myxomatosis?

A

Lagomorphs

70
Q

What lesions are associated with myxomatosis?

A

Raised, edematous lesions on skin
Conjunctivitis
Fever
Benign fibromas in Sylvilagus spp.
High mortality rate in Oryctolagus cuniculus

71
Q

How is myxomatosis transmitted?

A

Mechanical via biting arthropods (mosquitos, fleas)
Fomites (thorns)
Aerosolized respiratory droplets

72
Q

Define: Balanced Pathogenicity

A

As pathogen and host co-evolve, there is selective pressure for attenuated virulence of the pathogen and resistance of the host

VM639: Virology (30 decks)

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