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VM639: Virology > Reoviridae & Birnaviridae (Exam 2) > Flashcards

Reoviridae & Birnaviridae (Exam 2) Flashcards

1
Q

What are the general properties of reoviridae?

A

Double stranded
Segmented RNA genome
Icosahedral/spherical
Two or three concentric layers
Non-enveloped
Arthropod-borne and enteric pathogens

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2
Q

What are the steps of reoviridae replication?

A

Attachment
Receptor-mediated endocytosis
Outer capsid removed = core particle
mRNAs transcribed and released into cytoplasm
Genomic RNA synthesis/protein translation (viral factories)
New virions form
Release via accessory protein or cell lysis

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3
Q

What is included in the “virus factory” or reoviridae replication?

A

Intra-cytoplasmic inclusion body = virus factory
Inside = mRNA, dsRNA, viral proteins
Virions form in and around perimeter

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4
Q

What causes the large amounts of diversity in reoviridae?

A

Reassortment

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5
Q

What are the (6) requirements of reoviridae reassortment?

A
  1. Sympatry (same environment)
  2. Ecology (same species)
  3. Co-infection (infect same cells)
  4. Packaging (into same virion)
  5. Replicative compatibility
  6. Fitness (as fit or more than parental strains)
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6
Q

What disease is caused by rotavirus?

A

“milk scours”

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7
Q

What are the symptoms of “milk scours”?

A

Diarrhea, dehydration, acid-base imbalance

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8
Q

What is the host specificity of rotavirus groups?

A

Species specific!!

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9
Q

What is the structure of rotaviruses?

A

3 layer icosahedron (but round)

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10
Q

What is the structure of the rotavirus genome?

A

11 segment dsRNA genome

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11
Q

What is the stability of rotaviruses?

A

Stable in the environment (non-enveloped)
Stable at low pH
Resistant to lipid solvents

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12
Q

What is the pathogenesis of rotavirus?

A

Attacks villus tip cells
Causes atrophy, loss of digestive enzymes, dip in absorption –> malabsorption –> diarrhea

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13
Q

What enterotoxin is produced by rotaviruses? What does it cause?

A

Enterotoxin = NSP4
Causes osmotic imbalance in crypt cells, leading to secretory diarrhea

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14
Q

What age does rotavirus infect?

A

Neonatal/perinatal animals
2d to 8w of age

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15
Q

What clinical signs are associated with rotavirus?

A

Watery diarrhea, dehydration
Anorexia, depression, vomiting
+/- death due to severe dehydration or second infection

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16
Q

How is rotavirus transmitted?

A

Horizontal: fecal-oral route

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17
Q

What is the incubation period of rotavirus?

A

Quick
1-24 hours

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18
Q

What is the host range of rotavirus?

A

Every animal on earth

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19
Q

What are the risk factors to infection of rotavirus?

A

Poor sanitation
Lack of maternal immunity
Failure of passive transfer

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20
Q

What factors can increase morbidity of rotavirus?

A

Chilling, overcrowding
Other pathogens: E. coli, coronavirus, cryptosporidia

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21
Q

How is rotavirus diagnosed?

A

Latex agglutination (feces)
Histopathology
ELISA
PCR

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22
Q

How is rotavirus immunity acquired?

A

Good colostrum/milk quality and feeding
Vaccination or natural infection of dams

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23
Q

What sanitation/hygiene methods are used in prevention/control of rotavirus?

A

Disinfection of pens, feeding utensils, etc.
Rotavirus is not readily inactivated
Pasture rotation in range cattle operations

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24
Q

What (3) orbiviruses are listed by the World Organization of Animal Health?

A

Bluetongue virus
Epizootic hemorrhagic disease virus
African horse sickness virus

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25
Q

What cell types are targeted by orbivirus?

A

Endothelial cells!
Reticuloendothelial cells (macrophages, dendritic cells)

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26
Q

What is the pathogenesis of orbivirus?

A

Vasculitis
Vascular leakage

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27
Q

What are the pathological signs lesions of orbivirus?

A

Edema
Hemorrhage

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28
Q

How are orbiviruses transmitted?

A

Arthropod-borne: culicoides biting midges
Wind distribution
Virus acquired in blood meal from viremic animal
Shed in saliva in subsequent blood meal

29
Q

Where does orbivirus breed/replicate?

A

Breed in damp organic material
Replicates in midge (10 day extrinsic incubation period)

30
Q

What species does bluetongue virus infect?

A

Sheep
Cow

31
Q

What are the steps of pathogenesis of bluetongue virus?

A
  1. Culicoides bite
  2. Replication in local lymph nodes
  3. Primary viremia
  4. Replication in endothelial and reticuloendothelial cells (macrophages and dendritic cells)
  5. Close association with RBCs, secondary viermia
  6. Pulmonary edema, petechial hemorrhages in pericardium, vasculitis/edema/coronitis
32
Q

What are the clinical signs of bluetongue virus?

A

Edema (muzzle, ears, head, neck)
Coronitis, lameness, recumbency
Nasal discharge (serous to mucopurulent)
Fever
“Wool break”
Salivating, hyperemia of oral mucosa, oral ulcers, frothing of the mouth
Cyanosis of tongue

33
Q

How is bluetongue virus diagnosed?

A

PCR
Virus isolation (spleen, BM)
Serology

34
Q

How is bluetongue virus prevented?

A

Reduce culicoides exposure

35
Q

What species does epizootic hemorrhagic disease virus infect?

A

Deer

36
Q

What disease is caused by epizootic hemorrhagic disease virus?

A

Acute hemorrhagic fever

37
Q

What is the giveaway sign of epizootic hemorrhagic disease virus?

A

Deer carcasses in creeks, late summer/fall

38
Q

What 2 viruses are associated with dead deer in creek?

A

Epizootic hemorrhagic disease virus
Cervine adenovirus

39
Q

What symptoms are associated with epizootic hemorrhagic disease virus?

A

Fever, anorexia, ataxia
Lethargy, weakness
Salivation, oral ulcers
Hyperemia of mucous membranes, skin
Edema of conjunctiva, head, and neck
Lameness, hemorrhage of coronary band

40
Q

What are the mammalian host species of epizootic hemorrhagic disease virus?

A

White tailed deer
Mule deer
pronghorn

41
Q

How is epizootic hemorrhagic disease virus transmitted?

A

Culicoides

42
Q

How is epizootic hemorrhagic disease virus diagnosed?

A

PCR
Virus isolation
Serology

43
Q

How is epizootic hemorrhagic disease virus prevented?

A

Quarantine?
No vx yet
Reduce culicoides exposure

44
Q

What species does african horse sickness virus infect?

A

Horse

45
Q

What is the pathogenesis of african horse sickness virus?

A

Culicoides bite
Replication in local lymph nodes
Primary viremia
Infection of reticuloendothelial cells
Secondary viremia

46
Q

How does african horse sickness virus replicate?

A

Endothelial cells

47
Q

What symptoms are associated with african horse sickness virus?

A

Vasculitis
Pulmonary edema
Petechial hemorrhages: pericardium

48
Q

What are the antemortem clinical features of african horse sickness virus?

A

Frothy nasal discharge
Edema: conjunctiva and supraorbital fossae
Pulmonary edema
Up to 90-95% mortality in horses
Cardiac focal hemorrhage
Hydropericardium

49
Q

What are the specific mammalian hosts for african horse sickness virus?

A

Horses
Zebras (reservoir?)
Dogs, elephants, camels

50
Q

How is african horse sickness virus transmitted?

A

Culicoides

51
Q

African horse sickness virus is a _______ disease and is _______ to the united states.

A

Notifiable disease
Exotic to the US

52
Q

How is african horse sickness virus diagnosed?

A

Virus isolation (spleen)
Serology
PCR

53
Q

How is african horse sickness virus prevented?

A

Quarantine (60d)
Quadrivalent vaccine
Reduce exposure to culicoides (dawn/dusk, sprays)

54
Q

What are the symptoms associated with Colorado tick fever virus?

A

Fever, myalgia, headache, meningioencephalitis, hemorrhagic fever

55
Q

How is Colorado tick fever virus transmitted?

A

Tick borne, D. andersonii
Transmitted transtiadially

56
Q

What are the general characteristics of birnaviridae?

A

Double-stranded RNA with 2 segments
Icosahedral
Non-enveloped
Hardy in environment
Pathogens of birds, fish, and shellfish

57
Q

What diseases are caused by infectious bursal disease virus?

A

Gumboro disease
Acute diarrheal disease of young chicks
Immunosuppression in poultry

58
Q

What is the host range of infectious bursal disease virus?

A

Avian species
Chickens, turkeys, penguins

59
Q

How is infectious bursal disease virus transmitted?

A

Fecal-oral
Highly contagious
Persists in environment for up to 4 months
Harbored in meal worms for weeks
Resistant to most disinfectants

60
Q

What is the pathogenesis of infectious bursal disease virus?

A

Following oral inoculation, infect macrophages and lymphoid cells in the intestines
Replicates in the liver
Results in primary viremia and spread to the bursa of Fabricius
Lymphotropic for B cells
Secondary massive viremia and spread to other organs
Immunosuppression due to reduced humoral immune responsiveness

61
Q

What age group is most susceptible to infectious bursal disease virus?

A

Chicks 3 to 6 weeks of age (when bursa is developing)

62
Q

What is the morbidity/mortality of infectious bursal disease virus?

A

Morbidity: up to 100%
Mortality: from 0-30%

63
Q

What are the symptoms of infectious bursal disease virus?

A

Vent picking, soiled vent feathers
Anorexia, depression
Diarrhea, dehydration
Trembling, prostration

64
Q

What is the immunity to infectious bursal disease virus?

A

Maternal immunity important in reducing susceptibility of chicks

65
Q

What is the efficacy of vaccines with infectious bursal disease virus?

A

Vaccination of breeder is most effective
Vaccination of chicks

66
Q

How is infectious bursal disease virus controlled?

A

Disinfection/inactivation is difficult
Good husbandry (e.g. environmental temperature)

67
Q

What is the host range of infectious pancreatic necrosis virus?

A

Salmon, trout
Rockfish, flounder

68
Q

What disease is caused by infectious pancreatic necrosis virus?

A

Subclinical infections to highly pathogenic
90% mortality

69
Q

How is infectious pancreatic necrosis virus transmitted?

A

Survivors are chronic shedders, shed virus in feces, eggs, sperm

VM639: Virology (30 decks)

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