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Veterinary Virology > Families: Arteriviridae & Roniviridae > Flashcards

Families: Arteriviridae & Roniviridae Flashcards

1
Q

What is the morphology of Arterivirdae’s virion? What is its genome like?

A

spherical, with a smooth surface envelop and a ring-like structure

ssRNA positive sense

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2
Q

Where does Arterivirdae replicate? How does the virion form?

A

cytoplasm

buds into the rER and is released by exocytosis

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3
Q

What are 4 common Arteriviridae viruses that cause significant disease?

A
  1. equine arteritis virus (EAV)
  2. porcine reproductive and respiratory syndrome virus (PRRSV)
  3. lactate dehydrogenase-elevating virus (LDV) of mice breeding colonies
  4. simian hemorrhagic fever virus (SHFV)
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4
Q

What are the tropisms of equine arteritis virus (EAV) and porcine reproductive and respiratory syndrome virus (PRRSV)?

A
  • macrophages (monocytes)
  • respiratory and reproductive tracts
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5
Q

Arteriviridae replication cycle:

A
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6
Q

What order, family, and genus does equine arteritis virus (EAV) belong to?

A

Nidrovirales
Arteriviridae
Arterivirus

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7
Q

What species does equine arteritis virus (EAV) affect?

A

horses, donkeys, zebras, ponies (no outbreaks in mules reported)
- isolates vary in virulence
- only one serotype
- 10-70% infected stallions become carriers

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8
Q

What is the prevalence of equine arteritis virus (EAV) in horse breeds? What likely causes this?

A

Standardbreds > Thoroughbreds > Warmbloods > Quarterhorses

management practices

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9
Q

What are the 3 modes of transmission of equine arteritis virus (EAV)?

A
  1. RESPIRATORY - common where horses gather, like racetracks, sales, and shows
  2. VENEREAL - acutely infected mares and acutely/chronically infected stallions, typically via natural service and artificial insemination
  3. IN UTERO - fomites (equipment), mechanical (humans, other animals)
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10
Q

How does freezing infecting semen affect equine arteritis virus (EAV)?

A

no effect - semen remains infectious

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11
Q

What 4 things were observed in experimental infections of equine arteritis virus (EAV)?

A
  1. fever
  2. depression
  3. serous ocular and nasal discharge
  4. pregnant donkeys did not abort
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12
Q

Equine arteritis virus (EAV) transmission:

A
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13
Q

When are asymptomatic infections most commonly observed in equine arteritis virus (EAV)? Severe infections?

A

mares bred to long-term carriers

foals with respiratory signs and enteritis

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14
Q

What disease is seen in adults, pregnant mares, and stallions infected with equine arteritis virus (EAV)?

A

fever, depression, anorexia, edema

abortion, stillbirth

decreased fertility (acute), reduced sperm quality caused by increased scrotal temperature and edema, decreased libido

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15
Q

What are common postmortem lesions associated with equine arteritis virus (EAV) in acute cases, foals, and aborting mares?

A

edema, congestion, hemorrhages, fluid accumulation in body cavities

pulmonary edema, interstitial pneumonia, splenic infarcts, enteritis

endometrial hemorrhages, autolyzed fetus

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16
Q

What is the pathology of equine viral arteritis?

A
  • EAV infection (respiratory, venereal, in utero)
  • EAV in macrophages 24 hours PI
  • EAV in satellite lymph nodes 48 hours PI
  • EAV in endothelium and circulating monocytes 3 days PI
  • systemic distribution of EAV and male carrier state
  • EAV in blood vessel endothelium and medial myocytes 6-8 days PI
  • severe damage to blood vessels 10 days PI and abortion of infected newborn
  • EAV in renal tubular epithelium and shedding in urine 10-21 days PI
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17
Q

How can laboratory diagnosis of equine arteritis virus (EAV) occur?

A
  • virus isolation from semen from a carrier stallion on rabbit kidney cells
  • nucleic acid (RNA) detection in rtPCR
  • antigen detection via IHC and histopathology
  • serology: virus neutralization, complement fixation, agar gel immunodiffusion, indirect fluorescent antibody, fluorescent microsphere immunoassay, ELISA
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18
Q

How can carrier stallions be detected?

A

breeding to 2 seronegative mares

19
Q

What are 9 differential diagnoses for equine arteritis virus (EAV) infection?

A
  1. equine influenza
  2. equine infectious anemia
  3. African horse sickness
  4. Hendra virus
  5. equine rhinitis A and B viruses
  6. equine adenoviruses
  7. equine herpesviruses 1 and 4
  8. purpura hemorrhagica
  9. Berteroa incana (hoary alyssum) poisoning
20
Q

How is equine arteritis virus (EAV) infection controlled?

A
  • modified live vaccine for breeding mares
  • identification of persistently infected stallions
  • no breeding of anti-EAV antibody positive mares
21
Q

What 2 requirements should horses pass to be proven equine arteritis virus (EAV) negative and able to export?

A
  1. horses should be seronegative
  2. semen should be negative for virus isolation and rtPCR
22
Q

What are the 2 major porcine reproductive and respiratory syndome virus (PRRSV) genotypes?

A
  1. European prototypes - EU-type I (Lelystad virus)
  2. North American prototypes - NA-type II (VR-2332); ENDEMIC
23
Q

Porcine reproductive and respiratory syndrome virus (PRRSV) is constantly changing into different quasispecies. What do the European and North American strains share? What do they lack?

A
  • 55-70% nucleotide identity at the genome level
  • 50-80% amino acid similarity
  • cross protection - immunity produced by one strain does not protect against the other

(LV and VR-2332)

24
Q

In what 6 ways is porcine reproductive and respiratory syndrome virus (PRRSV) transmitted?

A

HORIZONTAL:
1. respiratory
2. fecal-oral
3. direct contact

VERTICAL:
4. trans-placental
5. semen (venereal)
6. artificial insemination

(spread every possible way)

25
Q

Genome structure and organization of PRRSV:

A
  • leader (ORF)
  • RNA polymerase (1a, 1b)
  • structural genes

7 strands of RNA

26
Q

What are the primary target cells for replication of porcine reproductive and respiratory syndrome virus (PRRSV)?

A

porcine alveolar macrophages (PAM)

27
Q

What 5 characteristics make the spread of porcine reproductive and respiratory syndrome virus (PRRSV) very easy?

A
  1. immunosuppressive
  2. PRSSV survives a long time in the cold and we conditions
  3. highly infectious - small amount is enough to infect entire herd
  4. persistent infection up to 200 days in some pig shedders
  5. easily mutated, making vaccine preparation hard
28
Q

Why is it hard to tell between infected and vaccinated individuals with porcine reproductive and respiratory syndrome virus (PRRSV)?

A

difficult to differentiate - requires DIVA tests

29
Q

What are 4 respiratory presentations of porcine reproductive and respiratory syndrome virus (PRRSV) infection?

A
  1. interstitial pneumonia with tan discoloration and mottling with a rubbery texture
  2. enlarged lymph nodes
  3. destruction of alveolar macrophages
  4. thumping - shallow and rapid breathing indicative of pneumonia
30
Q

What are 5 reproductive presentations of porcine reproductive and respiratory syndrome virus (PRRSV)?

A
  1. abortion
  2. stillbirth
  3. mummification
  4. virus shed in semen
  5. impacts on semen quality
31
Q

What presentation of porcine reproductive and respiratory syndrome virus (PRRSV) is common in the European prototype?

A

(EU type I - LV)

blue ear - edema and cyanosis

32
Q

How can porcine reproductive and respiratory syndrome virus (PRRSV) infection be diagnosed?

A
  • fluorescent antibody examination of frozen tissue
  • PCR, especially in fetal materials from abortion
  • restriction fragment length polymorphism
  • virus isolation
  • viral genome sequencing
  • IHC
  • ELISA
  • immunoenzymatic staining assay: indirect immunofluoresence
  • viral infection neutralization test
33
Q

What is the purpose of the porcine reproductive and respiratory syndrome virus (PRRSV) vaccine?

A

decrease titer and duration of viremia/viral shedding
- modified live vaccine not safe for naive pregnant females

34
Q

What are 4 management control measures that can prevent porcine reproductive and respiratory syndrome virus (PRRSV) infection?

A
  1. biosecurity (all-in-all-out)
  2. reduce concurrent infection
  3. replacement of gilts
  4. checking AI semen used
35
Q

When was simian hemorrhagic fever virus first noticed? What are 7 clinical signs?

A

macaques imported from India in 1964

  1. fever
  2. facial edema
  3. anorexia
  4. dehydration
  5. skin petechiae
  6. diarrhea
  7. hemorrhage
36
Q

How is simian hemorrhagic fever virus transmitted? What are the 2 target cells?

A

blood-to-blood transmission with 100% mortality within 5-25 days

  1. macrophages
  2. dendritic cells
37
Q

What species can Toroviruses affect? What shape does it take?

A

equids, bovines, humans, swine

torus = circular convex molding (doughnut)
- capsid may be bent into an open torus, coferring a biconcave disk/kidney shape or may be straight, resulting in a rod-shaped particle

38
Q

Torovirus (ToV) vs. Coronavirus (CoV):

A
39
Q

What are 4 common Toroviruses?

A
  1. bovine torovirus Breda I
  2. equine torovirus strain Berne
  3. human torovirus
  4. porcine torovirus Merkelo
40
Q

In what animals is porcine torovirus (PToV) most commonly found in? What was used to detect it? What else can be used?

A

piglets with diarrhea

immunoelectron microscopy
- neutralization assays
- indirect ELISA
- PCR**

41
Q

What is the shape of Roniviridae virions?

A

enveleoped baciliform particles with a helical nucleocapsid composed of the nucelocapsid protein (p20) surrounded by a lipid envelop containing two transmembrane glycoproteins (gp64, gp116)

42
Q

What is the genome of Roniviridae like? Where does it replicate?

A

non-segmented, positive-sense ssRNA with 5-6 long open reading frames

cytoplasm with nucleocapsids budding at the membrane of the rER and Golgi

43
Q

Where is the primary Roniviridae of veterinary importance and its 2 genotypes? What does it typically infect? What are the primary natural hosts?

A

Okavirus - gill-associated virus, yellow-head virus

crustaceans - giant tiger shrimp (Penaeus monodon)

44
Q

How does gill-associated virus (GAV) typically affect shrimp?

A

chronic infection in healthy brood stock and farmed black tiger prawns

Veterinary Virology (25 decks)

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