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Poxviridae Flashcards

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1
Q

Describe the look of pox viruses VS parapoxvirus.

A
  1. Poxvirus
    -lg, some enveloped, DNA virus, complex symmetry
    -pleomorphic, brick shaped, irregular surface w tubular/globular structures projecting
  2. Parapoxvirus
    -ovoid w thread like surface tubules arranged in cross cross
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2
Q

Describe IMV & EEV of pox viruses.

A
  1. IMV
    -intracellular mature virus
    -infectious
    -inner membrane only
    -virions released by disruption of host cell
  2. EEV
    -extracellular enveloped virus
    -infectious
    -envelope + inner membrane
    -virions released via budding
    *IMP for spread of virions bc taken up by cells more readily
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3
Q

Describe pox virus structure.

A

-virion outer layer encloses dumbbell shaped core + 2 lateral bodies
-core = viral DNA + proteins
-200+ genes in genome & 100 encode proteins
>genome = single molecule of linear double stranded DNA
>proteins encoded are enzymes in nucleic acid syn & virion structural components + proteins that counteract host adaptive & innate IR

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4
Q

Describe replication in poxvirus.

A

-replication in cytoplasm
>encode enzymes required for transcription & replication of viral genome
-after replication virion released by:
>budding = enveloped virions
>exocytosis
>cell lysis = non enveloped virions (most)

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5
Q

Describe stability of poxvirus.

A

-high environmental stability & stay inf for months
-low lipid content = less sensitive to organic solvents/disinf compared to other enveloped virus
-high resistance to drying
>survive years in dried scabs or other virus laden material

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6
Q

Describe transmission of poxvirus.

A

transmitted between animals
1. Skin
-cant inf intact skin
2. Respiratory route
-inhale aerosol
3. Mechanically transmitted
-biting arthropods (myxoma virus & avipoxvirus)

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7
Q

Describe the pathogenesis & immunity of poxvirus.

A

-highly epitheliotropic = cause cutaneous skin lesion
-systemic disease in bird & wild animals
-host specific
>orthopoxvirus inf wide range of species

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8
Q

Describe the spread of poxvirus.

A

-systemic circ via lymphatic system
-secondary viremia disseminates the virus back to skin & other target organ

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9
Q

Describe the skin lesions in pox virus infection.

A

Ma
Pa
Ve
Pu
Sca sca

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10
Q

Describe orthopoxvirus.

A

‘Cowpox’
1. Distribution
-endemic in Europe & Asia
2. Host
-cattle, cats, humans, zoo animals, etc
3. Reservoir
-rodents

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11
Q

Describe cowpox in cattle.

A
  1. Transmission
    -cow to cow via inf milker hand or teat cup
    -inf farm cats can transmit disease
  2. Economic imp
    -loss of $ to farmer bc of milking = soreness of teats & mastitis from secondary bacterial inf
  3. Clinical findings
    -cows mildly febrile, papules on teats & udder -> sucking calves develop lesions in mouth
    -vesicles not evident or may rupture readily, leaving raw, ulcerated areas that form scabs
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12
Q

Describe cow pox in cats.

A
  1. Transmission
    -skin inoculation (bite or wound)
    -rodents
    -exotic cat = viral pneumonia
  2. CS Primary lesion
    -skin lesion on head, neck, forelimb
    -small scabbed wound to lg abscess
  3. CS Secondary lesion
    -2-4d primary lesion develop into discrete, circular, ulcerated papules
    -ulcers become covered in scabs & healing complete by 6wk
    -cats show no signs other than skin lesions but 20% develop mild coryza or conjunctivitis
    -complication from secondary bacterial inf
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13
Q

Describe cow pox in humans.

A
  1. Transmission
    -direct contact w cats (most common)
    -rarely from rodents/zoo animals
    -virus not commonly found in cattle
  2. CS
    -macropapular lesion on hands & face -> develop into vesicular & ulcerative lesions
    -enlarged painful local LN
    -fever, vomit, sore throat
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14
Q

Describe monkey pox in humans.

A

viral zoonosis w symptoms in humans similar to those seen in small pox patients
1. Transmission
-primary inf: direct contact w blood, body fluids, rash of inf animal (monkey, Gambian rat, squirrels in Africa)
-secondary inf: close contact w inf respiratory tract excretion w the skin lesion of inf person or recently contaminated objects

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15
Q

Describe the different types of parapox viruses.

A
  1. Pseudocowpox virus (cattle & humans)
  2. Contagious ecthyma/orf virus (sheep, goat, human)
  3. Bovine papular stomatitis virus (cattle, humans)
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16
Q

Describe pseudocowpox virus.

A
  1. Definition
    -viral skin disease that causes mild sores on teats & udder of cattle
    -inf humans = milks nodules
    >dairy farmer, vet
  2. Etiology
    -member of parapoxvirus
  3. Epidemiology
    -most countries
  4. Transmission
    -source of inf = inf cattle
    -contaminated milk hand, teat cup
    -biting insect
    -calves inf during suckling inf teats
    -semen of bulls
  5. Pathogenesis
    -hyperplasia or squamous epi
  6. CS
    -mild
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17
Q

Describe pseudo cow pox virus acute VS chronic lesions.

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A
  1. Acute
    Erythema -> papules -> vesicle or pustule -> rupture -> scab
    -scab becomes elevated due to accumulation of granulation tissue
    -after 7-10d the scab falls off leaving a horseshoe shaped ring of small scabs surrounding a small wart like granuloma
  2. Chronic
    -start as erythema
    -yellow gray, soft scurfy scabs rubbed off during milking
    -skin is corrugated
    -no pain
    -lesion persist for months
18
Q

Describe the diagnosis & differential diagnosis of pseudocowpox.

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A
  1. Diagnosis
    -horse shoe shaped ring like lesion = pathognomic
    -isolation & detection of virus via various diagnostic lab methods from vesicular fluid or from teat skin
  2. Differential diagnosis
    -cow pox virus
    -bovine herpes virus ulcerative mammilitis
    -vesicular stomatitis
    -udder impetigo (bacterial dermatitis = sm pustules)
    -teat chaps & frost bite
    -black spot (hyperkeratosis)
19
Q

Describe the treatment & prevention of pseudocowpox.

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A
  1. Treatment
    -removal of scabs
    -burn scabs to prevent environmental contamination
    -apply emollient ointment before milking
    -apply astringent prep after milking
  2. Prevention
    -disinf + iodophor teat dip
    -isolation & treatment of inf cow
    -reduce teat trauma
20
Q

Describe contagious ecthyma.

Study These Flashcards
A

‘Orf’
1. Etiology
-parapoxvirus
2. Host
-sheep, goat (mostly lamb, kids)
3. Distribution
-worldwide

21
Q

Describe contagious ecthyma transmission.

Study These Flashcards
A

-scab fall off have virus
-virus stable in environment for long time under dry conditions
-contaminated instruments (docking, ear tagging)
-rapid spread
-inf healthy animal thru damage skin
-oral lesion in lambs or kids from nursing dams w teat lesions (vice versa)

22
Q

Describe contagious ecthyma pathogenesis.

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A

-damage of skin establish inf
-skin reaction to viral inf = cell response w necrosis & sloughing of epi & underlying stratum papillare of dermis
-cutaneous response to inf = delayed type hypersensitivity reaction + influx of inflam cells
Macule -> papule -> vesicle -> pustule -> ulcers -> scab

23
Q

Describe the clinical signs of contagious ecthyma.

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A

-first lesion in mucocutaneous junction + swelling of lips -> spread to muzzle & nostril surrounding hairy skin & buccal mucosa
>discomfort from lesion -> anorexia & weight loss
-affected lambs/kids inf ewes or goats = lesion on teat
>secondary bacterial inf -> mastitis
-severe: lesion in genital, coronets, ears
>lameness, infertility
-scabs drop off & underlying tissue heal w/o scarring -> complication from secondary bacterial inf or invasion of lesion by fly larvae
-malignant form of disease seen in sheep

24
Q

Describe contagious ecthyma vaccine.

Study These Flashcards
A

-prepared from suspension of scabs in glycerol saline & painted onto small area of scarified skin inside thigh = localized lesion develops
-DONT vaccinate on farms that dont have an issue w orf
-inspect lamb 1 week after vaccine for local reaction = indicated viability of vaccine
-vaccine last for 1-2y (not long lasting immunity)
-vaccinate:
1. Problem flocks/herds & lambs/kids
2. Pregnant ewes before lambing

25
Describe orf in humans.
-macropapular lesion & lg nodular lesion in finger, hand, arm, face, penis -secondary bacterial inf cause complications
26
Describe Capripoxvirus.
1. Sheep pox 2. Goat pox 3. Lumpy skin disease of cattle
27
Describe sheep pox & goat pox.
*thought to be strain of same virus but genetic seq demonstrated sep virus *most strain host specific & cause severe CS in sheep/goat while some have equal virulence in both species -cant be distinguished via serological test like viral neutralization -related to lumpy skin disease in cattle (LSDV doesnt cause disease in shoats) 1. Etiology -capripox virus 2. Distribution -endemic in Africa, Asia, parts of Europe
28
Describe the transmission of sheep pox & goat pox.
-highly contagious -virus enter respiratory tract & transmission by aerosol route -spread thru MM or abraded skin, esp by direct contact w contaminated iatrogenic materials -virus present in nasal & oral secretion for weeks after inf -virus survive in dry scab for months -mechanical transmission by biting arthropods
29
Describe the pathogenesis of sheep pox.
-systemic disease -incubation period followed by leukocyte associated viremia -virus localizes in skin & internal organs -deposit immune complex result in severe necrotizing vasculitis in arterioles & post capillary venules of skin (type III HS) = ischemic necrosis of dermis & overlying epi
30
Describe the clinical signs of sheep pox.
1. Malignant form -lambs & sus non native breeds (merino) -pox lesion on skin & buccal, respiratory, digestive & urinary tract mucosa -> pharynx, larynx, lungs, vagina, abomasum, spleen -secondary pneumonia common & abortion is rare -cutaneous nodule over whole body -> become vesicular, pustular, then scab -lesion heal leaving star shaped scar free of hair/wool -high mortality & case fatality rate (50%) 2. Benign form -more common in adults & resistant breeds -only skin lesion -no or milk systemic reaction
31
Describe sheep pox prevention & vaccine.
1. Prevention -notifiable !!! 2. Vaccine -lg variety of commercial vaccine -subunit, killed (temporary protection), live attenuated (>1 yr)
32
Describe goat pox.
-Africa, Asia, parts of Europe -reportable !!! -clinical similar to sheep pox -young kinds suffer systemic disease -milder form on adults
33
Describe lumpy skin disease.
1. Etiology -capripoxvirus 2. Distribution -enzootic in sub Saharan Africa, Middle East, iraq 3. Transmission -arthropod vector (most common) -direct contact 4. Host -cattle of all ages & types are sus 5. CS -fever, multi nodular lesions on skin & MM, lymphadenopathy
34
Describe suipoxvirus.
‘Swinepox’ 1. Etiology -suipoxvirus 2. Distribution -worldwide -sporadic 3. Host -pigs -benign w low mortality & low morbidity in older pig -high case fatality in congenital inf & young suckling pig 4. Transmission -direct contact w skin injury -virus survive in scab for yrs -mechanical transmission by pig louse Haematopinus suis (carry virus for weeks or months), flies, insects -transplacental inf of neonatal pig 5. Control -eradicate lice -no vaccine
35
Describe swine pox clinical signs.
-typical pox lesion >anywhere but mostly skin of abdomen & inner thigh -exudative epi (greasy pig disease) & secondary bacterial dermatitis -severe: esp congenital inf -> lesion occur in URT & GIT
36
Describe Avipoxvirus.
‘Fowl pox’ 1. Etiology -Avipoxvirus 2. Host -highly inf disease of poultry & turkeys 3. Distribution -worldwide 4. Transmission -resistant to desiccation -survive in exfoliated scabs for long periods -routes: >within flock thru wounds in mouth, comb, wattle, skin >mechanically via mosquito, lice ,ticks >aerosol
37
Describe the clinical signs of fowlpox.
1. Cutaneous form (dry) -most common -low mortality -results from injury by biting arthropod, mechanical transmission to injured skin -small papule on comb, wattle, beak >legs, feet, cloaca less common -nodules become yellow -> scab -fall in egg prod -recover in 4 wk 2. Diphtheritic form (wet) -caused by droplet inf -inf of MM, pharynx, larynx, trachea -lesion can cause death by asphyxiation -poor prognosis 3. Ocular form -conjunctivitis -exudate under eye lid
38
Describe avipoxvirus bollinger & borrel bodies.
1. Bollinger -eosinophilic granular intracytoplasmic inclusion bodies 2. Borrel -occur inside bollinger bodies -spherical bodies obtained by tryptic digestion of bollinger bodies
39
Describe fowlpox control.
1. Vaccine -modified live fowlpox or pigeon pox virus of chicken embryo or avian cell culture origin avail commercially -recombinant fowl pox vectored vaccines 2. Control mosquito & other biting insects
40
Describe unclassified pox virus.
‘Ulcerative dermatosis of sheep’ 1. Transmission -virus inf thru damaged skin or by coitus 2. CS *lesion usually ulcers w raw crater that bleeds easily* A) lip & leg ulceration B) venereal form >transmitted ulceration of prepuce & penis or vulva >ram becomes unfit for natural breeding
41
Describe the diagnosis of poxvirus.
1. CS 2. Sampling material -scrape skin lesion, vesicular fluid, crust, scab 3. Electron microscopy -morphology & size 4. Histopath *intracytoplasmic inclusion bodies* A) type B or Guarneri inclusion bodies = most poxvirus >slightly basophilic >viral particles & protein aggregates B) type A or ATI inclusion bodies >cowpox & ectromelia virus >strongly eosinophilic C) bollinger & borrel bodies >avipoxvirus 5. Inoculation in embryonated egg >CAM = pock lesion >parapoxvirus dont multiply in chicken embryo 6. Serological assay (ELISA) 7. Detection of poxvirus nucleic acid by PCR

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