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VMS 2006 > Pestiviruses and Teratogenic viruses > Flashcards

Pestiviruses and Teratogenic viruses Flashcards

1
Q

What is a teratogen?

A

A teratogen is an agent that can disturb the development of an embryo or fetus

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2
Q

What are some examples of teratogens?

A
  • radiation
  • maternal infections
  • chemicals
  • drugs
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3
Q

Give 4 examples of teratogenic viruses

A
  1. Blue tongue
  2. Japanese B encephalitis
  3. Epizootic haemorrhagic disease
  4. BVD
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4
Q

What is the genome organisation of a pestivirus?

A
  • Single-stranded, positive-sense RNA virus of genome 12.3kb
  • single open reading frame is translated to different polyproteins
  • the virion is enveloped- size 40-60nm is diameter
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5
Q

What is the structure of the pestivirus virion?

A
  • Enveloped
  • spherical
  • 50nm in diameter
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6
Q

How many encoded proteins do mature pestivirus virions have?

A

three virus-encoded proteins

Erns, E1, E2

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7
Q

What is the immundominant glycoprotein in pestiviruses?

A

E2

carries neutralising epitopes

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8
Q

What are the two main genotypes of BVDV?

A

BVDV-1 and BVDV-2

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9
Q

What is the most common BVDV genotype in the UK?

A

BVDV-1

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10
Q

What is the host range of BVDV?

A
  • Sheep
  • Goats
  • Pigs
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11
Q

What is the clinical presentation of BVDV?

A
  • Acute enteric, respiratory disease
  • Reproductive and foetal disease in susceptible breeding females
  • Mucousal disease
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12
Q

What are the two biotypes of BVDV?

A
  • Non-Cytopathogenic
  • Cytopathogenic
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13
Q

What does infection of a seronegative animal with BVDV lead to?

A

a transient, acute, infection that usually causes no or mild clinical symptoms

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14
Q

When does persistent BVDV infection occur?

A

Infection of ncp but not cp
occurs in month 2-4

persistent infection of the fetus

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15
Q

What happens when a BVDV infection occurs late in gestation?

A

abortion and malformation

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16
Q

What is the definition of a persistent infection?

A

animal is already infected with the virus when it is born and remains infected throughout its entire life

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17
Q

What happens when the foetus is infected in the first 90 days of life?

BVDV

A
  • The foetus becomes immunotolerant to the virus
  • Virus therefore survives and replicates
  • the animals can act as a reservoir of infection to the rest of the herd
  • they are also susceptible to mucousal disease
18
Q

In what cattle does mucousal disease develop?

A

Only develops in PI cattle

associated with the mutation of BVDV

19
Q

Where is BVDV localised?

A

lymphoid tissue before spreading to the gastrointestinal epithelium

20
Q

What does mucousal disease cause in keratinocytes?

A

Causes necrosis of keratinocytes, causing erosion/ ulceration

21
Q

What does fluid leakage from the ulceration post BVDV lead to?

A

Diarrhoea, Dehydration and bacterial infection

inevitably fatal

22
Q

What are the three different ways bulls can get BVDV?

A
  1. Male calves are born PI (persistent infection)
  2. Post-pubertal bulls can be exposed to BVDV as a transient infection (they shed the virus in semen for up to 28 days)- bulls then mount an immune response to the virus
  3. Post-pubertal bulls exposed to BVDV can be acutely infected but develop persistent testicular infection- this virus is cleared systemically
23
Q

What are the three ways you can diagnose BVDV?

A
  • Virus/ antigen detection- virus isolation from the semen
  • BVDV-specific antigen detection assays (blood samples, ear notches, milk testing)- fluorescent antibody test
  • BVDV- specific antibody detection- serum neutralisation test
24
Q

How can you control BVDV within a herd?

A
  • Target PI animals alongside a good vaccination programme
  • Test and cull schemes
25
Q

Why are BVDV vaccinations important?

A
  • Prevent the infection of the fetus
  • Reduce reproductive losses
  • Prevent production of PI animals and reduce the transmission cycle
26
Q

In what animal species is Classical Swine Fever Virus notifiable?

A

Notifiable in pigs and wild boar

27
Q

Where does classical swine fever virus survive?

A

fomites and pig meat such as sausage

28
Q

At what pH is CSFV inactivated?

A

rapidly inactivated at <3 or >10

29
Q

How thermally stable is classical swine fever?

A
  • Inactivated by 36 minutes at 70 degrees
  • the thermal stability is dependent on the matrix
30
Q

What CSFV sensitive to?

A

Organic solvents, Detergents and UV

31
Q

How can CSFV be transmissed directly?

A
  • Pig to pig contact
  • Oral, Nasal secretions
  • Feces, Urine, Blood, Semen
  • Transplacental
  • Contact with wild boar
32
Q

How is CSFV transmissed indirectly?

A
  • Arthropods, birds
  • Rodents, foxes
  • Infected pig pens
  • Lorries, equipment
33
Q

What is vertical CSFV transmission?

A

transmission across the placenta during gestation to produce congenitally infected piglets

34
Q

What is the pathogenesis of CSFV?

A
  • Virus enters the oral pharynx and replicates in the palatine tonsil
  • pyrexia, anorexia, leucopenia, generalised petechia
  • Haemorrhagic lymphadenitis in young pigs
  • Intestinal lesions of lymphoid tissue
  • CNS lesions can occur with tremors and incoordination
35
Q

What does CSFV in-utero transmission look like?

A
  • Cross-uterine congenital infection with cerebellar hypoplasia or growth retardation
  • Foetal death, abortion, congenital damage
36
Q

How can you prevent CSFV?

A
  • Do not feed uncooked food to swine
  • Disinfect boots/ Clean overalls
  • Quarantine newly introduced animals
  • Protect animals from feral pigs/ boar
37
Q

What species does border disease affect?

A
  • ewes, goats, ocassionally cattle
38
Q

What does border disease cause in flocks?

A
  • Significant abortion
  • classic outcome = ‘hairy-shaker lamb’
39
Q

What are the clinical signs of mucousal disease?

A
  • BVDV is localised to the lymphoid tissue then spreads to the gastrointestinal epithelium
  • There is then necrosis of keratinocytes
  • Fluid leakahe leads to diarrhea, dehydration and bacterial infection -> inevitably fatal
40
Q

How long does the shed BVDV virus last in semen?

A

Up to 28 days
* Bulls will mount an immune response to the virus which prevents further shedding

41
Q

What do persiently infect animals act as a d what are they susceptible to?

A
  • they act as reservoirs of infection
  • they are susceptible to mucousal disease
42
Q

What are the two vaccines for BVDV?

A
  • Inactivated
  • Modified Live vaccine

VMS 2006 (25 decks)

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