Exam 2 - Family: Poxviridae Flashcards Preview

Virology > Exam 2 - Family: Poxviridae > Flashcards

Flashcards in Exam 2 - Family: Poxviridae Deck (86):
1

Two subfamilies

Chordopoxvirinae (poxviruses of vertebrates) and Entomopoxvirinae (poxviruses of insects)

2

8 Genera in the subfamily Chordopoxvirinae

1. Genus: Orthopoxvirus
2. Genus: Parapoxvirus
3. Genus: Avipoxvirus
4. Genus: Capripoxvirus
5. Genus: Leporipoxvirus
6. Genus: Suipoxvirus
7. Genus: Molluscipoxvirus (Myxoma virus)
8. Genus: Yatapoxvirus (Yaba Monkey Tumor Virus)

3

Properties of Poxviruses

- Large, sometimes enveloped doubled stranded DNA viruses.
- Pleomorphic, brick shaped Possess an irregular surface of projecting tubular or globular structures
- Do not conform to icosahedral or helical symmetry.

4

Genus: Parapoxvirus properties

Ovoid, covered with long thread-like surface tubules, arranged in crisscross fashion, resembling a ball of yarn.

5

Two distinct infectious poxvirus particles exists

Intracellular Mature Virus (IMV) and Extracellular Enveloped Virus (EEV)

6

Extracellular Enveloped Virus (EEV)

Contains two membranes: envelope and inner membrane. Are released by budding that contain virus encoded proteins from host cells membrane.

7

Intracellular Mature Virus (IMV)

Only have an inner membrane. Come out by disruption of host cell and have only inner membrane.

8

Poxvirus Replication

Occurs in cytoplasm. Unlike other DNA viruses, poxviruses have evolved to encode the enzymes required for transcription and replication of the viral genome.

9

Poxvirus Antigenic Characteristics

Group-specific Nucleoprotein (NP), genetic recombination among the viruses

10

Poxvirus Stability

Unlike other enveloped viruses, there is high environmental stability and remain infectious. Less sensitive to organic solvents/disinfectants due to low lipid content. High resistance of drying. Can survive for many months and years in dried scabs.

11

Poxvirus Transmission - Skin

Only with broken or lacerated skin.

12

Poxvirus Transmission - Respiratory route

Aerosol route, typically most common route

13

Poxvirus Transmission - mechanical

Biting of arthropods

14

Poxvirus Pathogenesis and Immunity

Are highly epitheliotropic. Can cause systemic diseases, and are host specific.

15

Spread of Poxvirus

Gains access to the systemic circulation via the lymphatic system. Secondary viremia disseminates the virus back to the skin.

16

Chronological pathway of skin lesions poxvirus

Macule, Papule, Vesicle, Pustule, Ulcer, Scab

Ma- Pa-Ve-PuU-Sca

17

Genus: Orthopoxvirus

Cowpox in cattle, cats and humans; Monkeypox

18

Cowpox Distribution

Endemic only in Europe and Asia.

(definition of endemic: regularly found among particular people or in a certain area)

19

Cowpox Reservoir

Rodents

20

Cowpox in Cattle - Transmission

From cow to cow, infected milker's hands or contaminated teat cups

21

Cowpox in Cattle - Incubation Period

3-7 days

22

Cowpox in Cattle - Clinical Findings

Papular lesions appear on the teats and udder or in mouths of suckling calves.

23

Cowpox in Cats - Transmission

Typically through bite or skin wound. Most commonly from rodents. Can be oro-nasal route.

24

Cowpox in Cats - Clinical signs (Primary Lesions)

Single primary lesion usually on head, neck or forelimb

25

Cowpox in Cats - Clinical signs (Secondary Lesions)

7-10 days after primary lesion, develop into discrete, circular, ulcerated papules. May develop mild coryza or conjunctivitis.

26

Cowpox in Humans - Transmission

Direct contact with cats, rarely from cattle.

27

Cowpox in Humans - Clinical signs

Macropapular lesions on hands and face. Enlarged painful local lymph nodes, some may report fever, vomiting, and sore throat.

28

Monkeypox in Humans - Symptoms

Similar to smallpox

29

Monkeypox in Humans - Transmission (primary)

Results from direct contact with blood, bodily fluids, or rashes of infected animals.

30

Monkeypox in Humans - Transmission (secondary)

Results from close contact with infected respiratory tract excretions, with the skin lesions of an infected person or with recently contaminated objects.

31

Monkeypox - Distribution

Villages in Central and West Africa

32

Monkeypox - invasion period

(0-5 days) Fever, intense headache, lymphadenopathy, muscle pain

33

Monkeypox - Skin eruption period

Evolution of the rash from maculo-papules to vesicles, pustules, followed by crusts.

34

Monkeypox in Monkeys

The disease in characterized by generalized skin eruptions, developing to papules on the trunk, face palms and soles.

35

Genus: Parapoxviruses

1. Pseudocowpox
2. Contagious Ecthyma/Orf Virus

36

Pseudocowpox Definition

Pseudocowpox is a viral skin disease that causes mild sores on the teats and udders of cattle. This virus can also infect humans and the condition is commonly referred to as milker's nodule.

37

Pseudocowpox Transmission

Infected cattle, contaminated milker's hands and teat cups, biting insects, suckling calves, semen of bulls

38

Pseudocowpox Acute Lesions

Ma-Pa-Ve-PuU-Sca

Thick scab that is elevated due to accumulation of granulation tissue. After 7-10 days, the scab drops off, leaving a Horseshoe-shaped ring of small scabs surrounding a small wart-like granuloma.

39

Pseudocowpox Chronic Lesions

Yellow-gray, soft scurfy scabs which are rubbed off during milking. Skin is corrugated, no pain, lesions may persists for months.

40

Pseudocowpox Diagnosis

Horseshoe-shaped ring like lesion (pathognomonic for the disease). Isolation and detection of the virus by various diagnostic laboratory methods from vesicular fluid or from teat skin.

41

Pseudocowpox Treatment

Removal of scabs, burn the scabs to prevent environmental contamination, application of an emollient ointment before milking. Application of astrigent preparation after milking.

42

Pseudocowpox Prevention

Disinfection, use iodophor teat dip. Isolation and treatment of infected cows. Reduce teat trauma, as injuries to skin of teat predisposes to infection.

43

Pseudocowpox in Humans (The Milker's Nodule)

Causes a milk skin lesion known as Milker's Nodule. Lesions on the hands of dairy farmers milking teats or vets treating infected cows. Lesions may vary from multiple vesicles to a single, indurated nodule.

44

Contagious Ecthyma - Synonyms

ORF, Scabby Mouth, Contagious Pustular Dermatitis, Sore Mouth

45

Contagious Ecthyma - Host

Sheep and goats, primarily in lambs and goats kids

46

Contagious Ecthyma - Transmission

Contaminated instruments, virus infects healthy animals primarily through damaged skin, oral lesions in lambs or kids result from nursing dams with teat lesions, and vice-versa.

47

Contagious Ecthyma - Pathogenesis

Ma-Pa-Ve-PuU-Sca

The skin reaction to viral infection consists of a cellular response with necrosis and sloughing of the affected epidermis and underlying stratum papillare of the dermis. The cutaneous response to infection includes a delayed-type hypersensitivity reaction and an influx of inflammatory cells.

48

Contagious Ecthyma - Clinical signs

First: lesion develops in mucocutaneous junction and swelling of the lips.
Next: Lesions spread to the muzzle and nostrils and buccal mucosa
Secondary signs: anorexia and weight loss, bacterial infections cause mastitis, lameness, infertility.
Underlying tissue heals without scarring.

49

Contagious Ecthyma - Vaccination

- Does not offer long-lasting immunity.
- NO circumstances should the vaccine be used on farms that DO NOT have a problem with ORF.
- Inspect the lamb 1 week after vaccination.
- Lambs/kids may need to be vaccinated at 6-8 weeks to help prevent the disease
- Vaccinate pregnant ewes only 7-8 weeks before lambing.

50

Genus: Capripoxvirus

This includes sheep pox, goat pox, and lumpy skin disease of cattle.

51

Sheep and Goat Pox - Distribution

Endemic in Africa, Asia and parts of Europe.

52

REMEMBER!

SPV and GPV cannot be distinguished from each other with serological technique, including viral neutralization.

53

SPV and GPV - Transmission

Highly contagious. Enter respiratory tracts and is commonly by aerosol route. Spread through mucous membrane and abraded skin. Especially from contaminated iatrogenic materials. Mechanical transmission by biting arthropods

54

SPV and GPV - Pathogenesis

A systemic disease. Leukocyte associated viremia. Localized in skin and other internal organs. Results in ischemic necrosis of dermis and overlying epidermis.

55

SPV - Clinical signs - Malignant Form - Initial Signs

- Seen in lambs and Merino breeds.
- Incubation period: 4-8 days
- Marked depression and prostration
- High fever, salivation, lacrimation
- Edema of the eyelids
- Serous nasal discharge that becomes mucopurulent

56

SPV - Clinical signs - Malignant form - Later signs

- 1-2 days after, pox lesions develop on skin and buccal, respiratory, digestive, and urinary tract mucosa
- Extend to pharynx, larynx, vagina, abomasum and spleen.
- Cutaneous nodules are distributed widely over the body.
- Lesions heal leaving a STAR SHAPED SCAR , free of hair or wool

57

SPV - Clinical signs - Benign form

- More common in adults and resistant breeds
- Only skin lesions occur
- Mild systemic reactions

58

SPV - Prevention and control

REPORTABLE DISEASE!

- Ring vaccination, destruction of affected flocks and quarantine of infected premises should be instituted.

59

SPV - Vaccination

- Large variety of commercial vaccines are now available, including a subunit vaccine
- Killed vaccine elicit, at best, temporary protection
- Live attenuated vaccines offer excellent protection > 1 year

60

GPV - Properties

REPORTABLE DISEASE!
-Young kids suffer systemic disease with lesions on skin, respiratory and alimentary mucosa
- A flat hemorrhagic form of capripox is seen in some European goats and this has a high case fatality.

61

Lumpy Skin Disease - Distribution

Enzootic in sub-saharan Africa and Middle east with recent incursion in Iraq

(def. of enzootic: of, relating to, or denoting a disease that regularly affects animals in a particular district or at a particular season.)

62

Lumpy Skin Disease - Transmission

Arthropod vector (most common) and direct contact.

63

Lumpy Skin Disease - Host

Cattle

64

Lumpy Skin Disease - Clinical findings

Fever, multiple nodular lesions on skin and mucous membrane, lymphadenopathy. Morbidity reaches 80% during epizootics.

65

Lumpy Skin Disease - Control

Live attenuated vaccines available. Slaughter of affected and in-contact animals.

66

Genus: Suipoxvirus

Swinepox Virus

67

Swinepox Virus - Transmission

Direct contact with skin injury. Mechanical transmission by Haematopinus suis (pig louse). Evidence of transplacental infection.

68

Swinepox Virus - Clinical signs

- Transient fever
- Ma-Pa-Ve-PuU-Sca
- Skin lesions in abdomen and inner thigh
- Exudative epidermitis (greasy pig)

69

Swinepox Virus - Control

Eradication of lice from piggery. No commercially available vaccine.

70

Genus: Avipoxvirus

This includes: fowlpox and other avian poxviruses.

DO NOT CONFUSE WITH CHICKEN POX.

71

Fowlpox - Transmission

Extremely resistant to desiccation and can survive in exfoliated scabs for a long period.

Can be transmitted by minor wounds and abrasions. Mechanical vectors and possibly aerosol routes.

72

Fowlpox - Clinical Signs - The Cutaneous Form

The dry form. Most common form. Low mortality.
-Results from mechanical vectors or lacerated skin.
-Small papules on comb, wattles, neck, legs, feet and around cloaca
- Nodules become yellowish and progress to a thick scab
- Recover in about 4 weeks

73

Fowlpox - Clinical Signs - The Diphtheritic form

The wet form.
- Caused by droplet infection.
- Infection of mouth, pharynx, larynx and trachea mucosa
- Lesions coalesce and result in pseudomembrane that causes asphyxiation
- Prognosis is poor
- High morbidity

74

Fowlpox - Clinical Signs - Ocular form

Conjunctivitis, cheesy exudate accumulates under the eyelids

75

Bollinger bodies

Eosinophilic granular intracytoplasmic inclusion bodies

76

Borrel bodies

Occur inside bollinger bodies. Borrel bodies are minute spherical bodies obtained by tryptic digestion of bollinger bodies

77

Fowlpox - Control (vaccination)

MLV of fowlpox or pigeonpox virus of chicken embryo of avian cell culture origin are available commercially. Vaccines indicated in areas where the disease is endemic. In enzootic areas, vaccinated during the first week of life and then again 8-12 weeks later.

Control mosquito population and other biting insects.

78

Unclassified Poxviruses

Ulcerative Dermatosis of Sheep

79

Ulcerative Dermatosis of Sheep - Transmission

Virus infection through damaged skin or by coitus

80

Ulcerative Dermatosis of Sheep - Clinical forms

Regardless of location, lesions are usually ulcers with a raw crater that bleeds easily. Manifest in two forms:

1. Lip and leg ulceration
2. Venereal form

81

Lip and leg ulceration

-Formation of ulcers around the mouth and nose or on the legs (lips and leg ulceration)
- Face lesions occur on the upper lip, between the border of the lip and the nasal orifice, on the chin, and on the nose
- Foot lesions are seen anywhere between the coronet and the carpus or tarsus

82

Venereal form

- Venereally transmitted ulceration of the prepuce and penis or vulva
- Rarely, ulcers may extend to the glans penis so that the ram becomes unfit for natural breeding
- In ewes, edema, ulceration and scabbing of the vulva have less serious consequences
- Balanoposthitis

83

Balanoposthitis

Superficial necrosis of the skin of the mucosa of the prepuce and glans penis

84

Diagnosis of Poxviruses

- Clinical signs
- Sampling material (scrapings from skin lesions, vesicular fluid, crusts, scabs
- Electron Microscope (characteristic morphology and size of poxviruses. Orthopoxviruses are brick shaped. Parapoxviruses are ovoid)
- Histopathology: presence of characteristic intracytoplasmic inclusion bodies.
-Chorioallantoic membrane (CAM)
- PCR, ELISA, Pock Assay, etc.

85

Type B inclusion bodies

Guarnieri inclusion bodies. Most poxviruses induce presence of type B inclusion bodies. These are slighly basophilic and composed of viral particles and protein aggregates.

86

Type A inclusion bodies

ATI inclusion bodies. Some poxviruses (cowpox and ectromelia virus) induce type A bodies. They are more strongly eosinophilic.