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Virology Final Exam Summer 2015 > Bunyaviridae > Flashcards

Bunyaviridae Flashcards

1
Q

Describe the virion and genome of family Bunyaviridae?

A

Spherical, enveloped, with glycoprotein spikes but NO MATRIX PROTEIN
Three nucleocapsid segments with helical symmetry
Segmented negative sense single stranded RNA
RNA Segments: L, M, S

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2
Q

Where does replication of this virus occur?

A

Cytoplasm! Buds into golgi vesicles

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3
Q

This virus is generally ______ for vertebrae cells

A

Cytocidal

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4
Q

T or F: Genetic recombination occurs between closely related viruses

A

False! It’s not recombination, it’s reassortment

Segmented: ReaSsortment

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5
Q

What are the genuses of interest for us?

A

Arthropod borne: Orthobunyavirus, Phlebovirus, Nairovirus

Non-arthropod borne: Hantavirus

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6
Q

Which genus produces the clinical disease RIft Valley Fever (RVF) and what are its hosts?

A

Phlebovirus
Sheep, cattle, goats
Can infect humans!

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7
Q

How can RVF infect humans?

A

From percutaneous or aerosol exposure while slaughtering or handling infected aborted fetuses
Also from bites of infected mosquitoes (Aedes mosquito)
But no human to human transmission has been documented

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8
Q

Where are you most likely to find RVF?

A

Throughout most of Africa

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9
Q

What are the biological and mechanical vectors for RVF?

A

Biological: primary is Aedes mosquito and secondary is Culex and Anopheles mosquito
Mechanical: biting flies i.e. culicoides or midges

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10
Q

T or F: the epizootic cycle is characterized by local, normal transmission and usually happens during periods of normal rainfall

A

False! The epizootic cycle occurs during abnormally heavy rainfall and massive emergence of Aedes mosquitoes

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11
Q

How is the disease transmitted between Aedes mosquitoes?

A

Transovarially! Through eggs

These eggs hatch when there is abnormally heavy rainfall and cause the mass emergence of mosquitoes

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12
Q

Where does the RVF virus like to replicate?

Also describe the pathogenesis after an animal is infected

A

Liver, other major organs and results in widespread cell necrosis
*Extensive hepatocellular necrosis is common in terminally affected sheep
Encephalitis, hemorrhages in GI tract
Renal failure, hepatic necrosis, shock are primary causes of death

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13
Q

T or F: 90-100% of pregnant animals that get infected with RVF abort

A

Truuuuu

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14
Q

What are the clinical signs of RVF?

A

Sheep: mortality in young lambs, abortion, encelphalomyelitis in young animals
Cattle: less severe than sheep but still abortion
Livestock: fever, mortality, abortion, lethargy, inappetance, epistaxis, drop in milk production, death orrrr life long immunity?

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15
Q

How is RVF diagnosed?

A

Should be suspected when abnormally heavy rains and flooding are followed by abortions/mortality
And concurrent with influenza-like disease in people handling animals or products

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16
Q

Describe the control of RVF

A

Livestock vaccination
Vector control
Attenuated-live RVF vaccines produced in mouse brain and embryonated eggs for sheep (but not pregger ones because they can cause abortion)
Inactivated-virus vaccines are expensive but avoid abortion problem

17
Q

To what genus does Akabane disease belong?

A

Orthobunyavirus!

18
Q

What are the hosts of Akabane virus?

A

Cattle, sheep, goats

*Congenital disease

19
Q

How is akabane transmitted?

A

Biting midges (culicoides) and mosquitoes (aedes and culex)

20
Q

Describe the pathogenesis of Akabane disease

A

After bite, virus infects pregnant animal and reaches fetus
Most severe lesions result from infection at 3-4 months when CNS is developing
Results in encephalomyelitis and polymyositis
Viral infection of CNS causes hydraencephaly
Arthrogryposis (fixation of limbs, think pathology!!)

21
Q

Are there clinical signs associated with Akabane disease?

A

No clinical signs in adults and young animals

22
Q

How is Akabane virus diagnosed?

A

Detection of specific neutralizing antibody in serum from aborted fetuses or newborns (before colostrum)
Difficult to isolate after birth, but placenta and aborted fetus is a good shot

23
Q

Is Akabane virus reportable?

A

Yes!

24
Q

Are vaccines available for Akabane virus?

A

Yes, inactivated virus vaccine is available in Japan and Australia

25
Q

To which genus of bunyaviridae does Schmallenberg virus belong?

A

Orthobunyavirus

26
Q

General things about Schmallenberg virus, 1, 2, 3, go—-

A

Cattle, sheep, goats
European countries
Transmission by culicoides
Clin signs: malformed animals and diarrhea, abortion, reduced milk production in adults

Virology Final Exam Summer 2015 (9 decks)

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