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Veterinary Virology > Family: Bunyaviridae > Flashcards

Family: Bunyaviridae Flashcards

1
Q

Where does the name Bunyaviridae come from?

A

Bunyamwera = town in western Uganda, where Rift Valley fever virus was isolated in 1943

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2
Q

What are the 5 genera in Bunyaviridae? What do they infect?

A
  1. Orthobunyavirus - vertebrates
  2. Hantavirus - vertebrates
  3. Nairovirus - vertebrates
  4. Phlebovirus - vertebrates
  5. Tospovirus - plants (esp. tomatoes)
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3
Q

What is the structure of the Bunyaviridae virion?

A

spherical, enveloped virion with glycoprotein spikes and nucleocapsid segments with helical symmetry but lacks matrix proteins

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4
Q

What type of genome does Bunyaviridae have? Where does it replicate? How does it leave cells?

A

3 segment (L, M, S) negative-sense ssRNA genome that is 5’ capped

cytoplasm
budding into/from Golgi

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5
Q

How does Bunyaviridae differentially affect vertebrate and invertebrate cells? What tends to happen with closely related viruses in this family?

A

VERTERBRATE = cytocidal
INVERTEBRATES = non-cytocidal

genetic reassortment

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6
Q

Bunyaviridae RNA genome:

A

3 segments, 5’ capped

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7
Q

What causes Rift Valley fever? What is required for animal-to-animal transmission?

A

Rift Valley fever virus (RVFV)
- Kenya, Africa
- Bunyaviridae

mosquito vectors

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8
Q

What disease does Rift Valley fever virus cause? How does it affect humans?

A

fever-causing disease in sheep, cattle, and goats with high abortion rates and death in young animals

flu-like symptoms

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9
Q

Rift Valley fever virus replication cycle:

A
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10
Q

What are the 2 epidemiological cycles of Rift Valley fever?

A
  1. ENZOOTIC: constantly present in an animal population, but usually only affects a small number of animals at one time
  2. EPIZOOTIC: outbreak of disease affecting many animals of one kind at the same time (biological multiplication within mosquito vector)
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11
Q

Rift Valley fever distribution:

A
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12
Q

Where is Rift Valley fever most common? Why?

A

flood-prone areas, where female Aedes mosquitos lay eggs that have RVFV passed on and are able to lay dormant until heavy rainfall causes them to hatch

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13
Q

In what 4 ways is Rift Valley fever virus amplified?

A
  1. infection of other mosquitos
  2. establishment of disease in the environment
  3. large outbreaks
  4. humans can act as a source of the virus
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14
Q

In what 4 ways is Rift Valley fever virus transmitted? How is it not transmitted?

A
  1. vector - bite of infected mosquito
  2. direct contact - tissues or body fluids of infected animals via handling of birthing tissues and meat
  3. aerosol - inhalation during slaughter of infected animals or birthing process
  4. oral - drinking unpasteurized milk (not common)

person-to-person

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15
Q

How does species affect the intensity of infection of Rift Valley fever virus?

A
  • 100% death rate: lambs, calves, kids, puppies, kittens, some rodents
  • severe illness, abortion, death: sheep, cattle, goats, humans
  • severe illness, viremia, abortion: monkeys, camels, rats, squirrels
  • infection, viremia: horses, cats, dogs, monkeys
  • no infection: rodents, rabbits, birds
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16
Q

How does infection compare in adult cattle and calves?

A

ADULT: fever, weakness, anorexia, drooling, diarrhea, jaundice, 10% death rate, abortion rates can reach 100%

CALVES: fever, depression, sudden death (10-70%)

17
Q

How does Rift Valley fever virus affect sheep and goats?

A

signs begin within 3 days
- high rate of abortion at any stage
- foul diarrhea
- jaundice
- snotty nose
- death rate 20-30%
- adults appear normal

18
Q

How does Rift Valley fever affect dogs, cats, horses, pigs, and birds?

A

DOGS = abortion up to 100%, severe death and disease in puppies
CATS = death in kittens
HORSES = do not get sick
PIGS = do not get sick
BIRDS = do not get RVF

19
Q

How long does it take for symptoms to occur in Rift Valley fever in humans? What is the most common symptom? What 3 things happen in 1% of humans?

A

2-6 days post exposure

no signs to flu-like symptoms, like fever, headache, muscle and joint pain, nausea, and vomiting with recovery in 4-7 days

  1. inflammation of the retina, which may cause permanent damage
  2. bleeding disorder
  3. brain inflammation
20
Q

How is Rift Valley fever diagnosed?

A
  • detection of virus particles by EM
  • virus isolation
  • detection of Ag by serological techniques (IF, ELISA)
  • detection of the viral AB by serological techniques (ELISA, NT)
  • detection of NA by PCR
  • sequencing of viral genome
21
Q

In what 4 ways can Rift Valley fever virus infection be controlled?

A
  1. control of mosquito egg laying sites
  2. control of mosquito eggs and larvae
  3. control of adult mosquitos
  4. eliminate breeding places
    - drain or fill in low-lying areas
    - grade newly developed land
    - drainage holes
    - properly discard trash
    - clean gutters
    - change pet/stock water weekly
22
Q

What cases Akabane disease? How is it spread?

A

Akabane virus, a member of the Simbu serogroup of the family Bunyaviridae and genus Orthobunyaviridae

biting midges (Culicoides spp.)

23
Q

What animals does Akabane virus typically infect? What are 5 common clinical signs?

A
  1. abortion, stillbirth
  2. arthrogryposis
  3. hydranencephaly
  4. torticollis
  5. microencephaly
24
Q

What animals does Akabane disease most commonly affect? Why? Are humans susceptible?

A

cattle and sheep - long period of gestation and breeding throughout the year

no

25
Q

What is Aino virus? How is it transmitted? What is it linked to?

A

Simbu serotype in the family Bunyaviridae and genus Orthobunyaviridae (like Akabane virus)

insect vectors - biting midges (Culicoides gnats)

fatal deformities in sheep and goats

26
Q

What are 8 clinical signs of Aino virus infection?

A
  1. abortion/stillbirth/premature birth
  2. arthrogryposis
  3. scoliosis
  4. sunken eyes with cataracts
  5. maxillary retraction
  6. dental irregularities
  7. hydranencephaly
  8. cerebral hypoplasia or agenesis
27
Q

What is LaCrosse encephalitis virus (LACV)? When is prevalence the highest? What is the dead end host?

A

mosquito-transmitted (Aedes) virus that causes encephalitis (discovered in Wisconsin)

summer

humans

28
Q

What is Schmallenberg virus? What is it transmitted by?

A

member of the Simbu serogroup of Orthobunyaviruses discovered in 2011 near the German/Dutch border

Culocoides biting midges

29
Q

What 6 things do lambs and sheep congenitally infected with Schmallenberg virus show? What affects severity?

A
  1. arthrogryposis
  2. hydranencephaly
  3. torticollis
  4. kyphosis, lordosis, scoliosis
  5. ankylosis
  6. brahygnathia

gestational age of the fetus at infection

30
Q

What is Cache Valley Orthobunyavirus (CVV)? What was it first isolated from? What does it cause?

A

member of the Bunyamwera serogroup of Orthobunyavirus and order Bunyavirales

Culiseta inornata mosquitos in Utah’s Cache Valley

fatal encephalitis, multiorgan failure, and aborted/malformed lambs

31
Q

What 2 diseases do Hantaviruses cause in humans? How is it transmitted?

A
  1. hemorrhagic fever with renal syndrome (HFRS) - old world hantavirus
  2. Hantavirus pulmonary disease (HPS) - new world hantavirus

rodents

32
Q

What 5 Hantaviruses cause respiratory disease in the US?

A
  1. Sin Nombre virus
  2. Bayou virus
  3. Black Creek Canal virus
  4. Andes virus
  5. Laguna Negra virus
33
Q

How is Hantavirus infection diagnosed?

A
  • detection of viral antigens
  • detection of viral nucleic acids by rtPCR
  • seroconversion

Veterinary Virology (25 decks)

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