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422 Virology > lecture 4- BVDV and BLV > Flashcards

lecture 4- BVDV and BLV Flashcards

1
Q

what is BVDV

A

bovine viral diarrhea virus

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2
Q

How many types of BVDV are there

A

2 types with many classifications within each type

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3
Q

what are the envelope proteins of interest in the genome of BVDV

A

E ms, E1, E2

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4
Q

true or false: BVDV only infects bovine

A

false!!

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5
Q

is it likely that wildlife carry BVDV and transfer it to cows?

A

no- more likely the other way around

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6
Q

what are the requirements to be a potential wildlife reservoir for BVDV? 4 things

A

1) be susceptible to BVDV
2) shed BVDV (and replicate)
3) maintain BVDV in the population (shed it enough to maintain)
4) have sufficient contact with cattle that allow spillback infections

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7
Q

what happens with pigs that get BVDV

A

poor conception rates, abortion, stillborn piglets, often no clinical signs

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8
Q

what are hairy shakers?

A

sheep infected with BVDV that present with neurological signs/tremors

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9
Q

If a cow is infected with BVDV during her first month of pregnancy, what typically happens? why?

A

early emryonic death and return to estrus

BVDV infects mom and then the fetus who has no immunity

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10
Q

If a cow is infected with BVDV during her 2-4th month of pregnancy, what typically happens? why?

A

The calf will be persistently infected with BVDV and will be antibody negative. it is possible that abortion/malformation could occur too.

this happens because the fetus cannot yet distinguish between self and non-self antibodies

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11
Q

what does it mean if a cow is a PI for BVDV?

A

They are a carrier of the disease and will be shedding it, despite having no clinical signs. They are immunosuppressed.

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12
Q

If a cow is infected with BVDV during her 5-9 months of pregnancy, what typically happens? why?

A

the calf might be born normal with positive antibodies, or they might be aborted / have malformations

at this point the calf can recognize self from non-self, so can respond with antibodies to fight off infection.

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13
Q

what is the pathogenesis of BVDV?

A

oronasal infection
tonsils
regional lymphnodes
blood circulation
lymphoid tissue of the GI track and lungs
thymus/bone marrow/spleen
all other organs (depending on virulence)

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14
Q

in PIs, which organs test positive for BVDV? why is this significant?

A

all organs are BVDV positive, leading to immunosuppression

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15
Q

what does it mean if a PI calf is infected with cytopathic BVDV? how does it occur?

A

This happens in PI’s and is indicative of mucosal disease, in that this form causes cell death.

it occurs by a genetic mutation occurring in the non-cytopathic form of BVDV.

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16
Q

What does it mean if a PI cow is infected with non-cytopathic BVDV?

A

The disease is able to replicate without causing disturbance/cell death.

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17
Q

what are the clinical signs mucosal disease?

A

discharge from nose, foaming from mouth, lesions in oral cavity/esophagus

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18
Q

what is the genetic basis for mucosal disease?

A

non-cytopathic virus is mutated via RNA recombination at the NS2 NS3 junction, resulting in production of the NS3 protein next to NS2-3 polyprotein

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19
Q

why is mucosal disease considered a “fluke of evolution”?

A

it kills PIs (fast!)

20
Q

What is the most effective way to eradicate BVDV?

A

euthanasia of PIs

21
Q

how does vaccination affect the prevalence of PIs?

A

in unvaccinated herds, it is a ticking time bomb before an outbreak occurs, then nearly all calves will become PI

22
Q

is vaccinating PIs out of the herd effective?

A

no- its too late.

23
Q

what is BLV

A

bovine leukemia virus

24
Q

why is BLV important to the dairy industry?

A
  • decreased milk production
  • decreased cow longevity
  • clinical leukosis
  • export restrictions
  • animal welfare
  • consumer concerns
25
Q

can cows overcome BLV?

A

no- once they are infected, they are always infected

26
Q

is BLV significant in Canada?

A

yes! upwards of 90% of herds are infected

27
Q

what kind of virus is BLV

A

deltaretrovirus

28
Q

what cells does BLV infect?

A

B-lymphocytes (cells that make antibodies)

29
Q

what is the viral mechanism of BLV?

A

makes a copy of genome and inserts that into the DNA of cow

30
Q

what are the 3 ways that the immune system can respond to BLV?

A
  1. asymptomatic / aleukemic stage
  2. persistent lymphocytosis
  3. leukemia/lymphoma
31
Q

how does infection of CD5+ B cells by BLV impact B cells and T cells?

A

polyclonal expansion of B cells (increasing) and abnormal function of T cells and monocytes (decreased)

32
Q

in what 2 ways does BLV cause tumors?

A
  1. cis- activate oncogenes by inverting into genome
  2. trans- virus produces mediators that induce tumors
33
Q

what are clinical signs of BLV?

A

retrobulbar process -> exophtalmus, generalized edema, enlarged lymphnodes, cardial lymphosarcoma, other lymphosarcomas (spleen, intestinal)

34
Q

how is BLV transmitted between animals?

A

blood, colostrum, milk, in utero, natural breeding, iatrogenic, bulls

35
Q

what is used to test for BLV

A

blood or milk using antibody test

36
Q

how do you manage BLV?

A

biosecurity, minimize blood, monitor colostrum/milk

37
Q

what does it mean to have a high proviral load?

A

many cells contain copies of integrated provirus

38
Q

are proviruses (like BLV) silent?

A

no!

39
Q

is there a vaccine for BLV?

A

no

40
Q

what family is BVDV a part of?

A

Flaviviridae

41
Q

What family is BLV a part of

A

Retroviridae

42
Q

what is the structure of BVDV (Flavi)

A

enveloped, positive sense (ssRNA)

43
Q

what is the structure of BLV?

A

enveloped, positive sense

44
Q

what is the replication strategy of BVDV?

A

ssRNA+ (viral genome acts as mRNA)

recall the family is Flavi

45
Q

what is the replication strategy of BLV?

A

ssRNA+ retro (virion reverse transcriptase –> ssDNA –> cellular pol2 –> mRNA)

retroviruses insert into host genome

422 Virology (15 decks)

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