Pestivirus

Question 1

What is the family and genus?

Answer 1

• family - flaviviridae
• genus - pestivirus

Question 2

What are some of its features?

Answer 2

• single stranded
• +ve sense RNA virus
• enveloped

Question 3

What viruses does it include?

Answer 3

• CSFV
• BVDV
• BDV

Question 4

label

Answer 4

Question 5

What is the pathogenesis?

Answer 5

• depends on virus
• targets WBCs, gut, resp system, vasculature, CNS (foetus)
• cross placenta - abortion, persistent infections

Question 6

What happens if injected in early gestation?

Answer 6

• will get virus
• early embryonic death
• abortion
• no antibodies formed

Question 7

What happens if infected in late gestation?

Answer 7

• still have antibodies
• so virus will be gone before born

Question 8

What happens if infected after birth?

Answer 8

• has immune response needed

Question 9

What is CSFV?

Answer 9

• classical swine fever
• highly contagious
• notifiabel in pigs and wild boars
• one serotype - different strains
• eradicated in Uk - 1966
• last outbreak - 2000

Question 10

What countries is CSFV eradicated in?

Answer 10

• austrailia
• canada
• new zealand
• US
• most of western and central europe

Question 11

Describe the transmission of CSFV

Answer 11

• highly contagious - urine, tissues, faeces, blood, saliva, semen
  
  • ingestion of rubbish/ meat
  • direct or indirect contact - clothing (2 wks), skin cells, hair, bedding
  • vertical transmission - across placenta - congenitally affected

Question 12

What type of virus is CSFV?

Answer 12

• stable virus
• survive at high temp/ pH
  
  • need pH below 3 and above 11
  • 72 degrees for 1 min
  • 66 degrees for 30 mins
  • UV light
  • drying
  • bleaches

Question 13

What is the pregnant carrier sow syndrome?

Answer 13

• if infected 0-50 days - abortion, stillbirths, mummification
• 50-70 days - persistent infected offspring - dont produce neutralising antibodies
• 70-114 - late onset CSF

Question 14

Describe the pathogenesis of CSFV?

Answer 14

• tropism for vascular endothelial cells and phagocytic mononuclear cells
• cause vasculitis, thrombocytopenia, thrombosis of small vessels, DIC

Question 15

What is this showing?

Answer 15

• signs of CSF
  
  • haemorrhagic lymph nodes
  • dead patches in spleen
  • small haemorrhages in kidney
  • button ulcers in gut

Question 16

What are CSF clinical signs?

Answer 16

• 3 presentations:
  
  • acutely fatal
  • chronic
  • late onset/ congenital
• if have septicaemia/ high temp - APHA

Question 17

What biosecurity methods should be used for prevention of CSF?

Answer 17

• do not feed uncooked rubbish
• quarantine
• isolation
• no visitors
• PPE
• health records
• protect from wild pigs

Question 18

What surveillance for CSF?

Answer 18

• serological, virulence, clinical

Question 19

Where are vaccines used for CSF?

Answer 19

• only in endemic countries
• not in UK - cant see if theyve been naturally infected
• if found:
  
  • slaughter, containment, movement restrictions

Question 20

What is BVDV?

Answer 20

• BVDV-1/2
• BVDV-1 - most common
• infection - financial impact - due to repro and immunodeficient impacts
  
  • acute resp and enteric diseases
  • foetal and repro disease in susceptible breeding females
  • mucosal disease

Question 21

Acute disease -BVDV?

Answer 21

• young animals common
• subclinical or clinical
• clinical: diarrhoea, lethargy, inappetence, resp disease, milk drop
• immunosupression - prone to other infections
• high virulent strains - ulcerative oropharynx, larynx, haemorrhagic enteritis

Question 22

What are the outcomes of infections at different times during pregnancy for BVD?

Answer 22

• before mating - infertility (secreted in semen)
• 1 month - embryonic death and return to oestrus
• 2-9 months - abortion
• 25-90 days - PI
• 80-150 days - congenital defects

Question 23

What are the congenital malformations BVD?

Answer 23

• cerebellum hypoplasia
• alterations in cerebrum
• bone growth retardation
• lung growth retardation
• thymus growth retardation
• ataxia
• hair coat
• weak calves
• kidneys
• ocular lesions

Question 24

What are BVD PIs?

Answer 24

• infected in 1st trimester - 90 days
• immunotolerant to infection
• reservoir
• susceptible to mucosal disease

Question 25

What is mucosal disease?

Answer 25

• only occurs in PIs
• mutation in the BVD -
• goes from non-cytopathic to cytopathic
• localises in lymphatic tissue then to GI epithelium
• goes to keratinocytes - erosions and ulcers
• fluid leakage = diarrohea, dehydration, bacterial infections
• death - 1-3 weeks

Question 26

What is this?

Answer 26

• mucosal disease

Question 27

How do you diagnose BVD?

Answer 27

• virus - isolation - add to bovine cells - look for fluroescence - live virus
• genome - PCR
• antigens - ELISA - milk/ ear notches
• antibodies - seroconversion - milk/ ear notches

Question 28

Which test should be used in acute infection?

Answer 28

• PCR
• could use antigen ELISA/ isolation
• couldnt use antibodies - need a couple of weeks to make antigens

Question 29

What test should be used for a PI animal?

Answer 29

• Isolation
• PCR
• ELISA

Question 30

What test should be used when bulk testing milk?

Answer 30

• ELISA
• Ab - seroconversion
• could use PCR and isolation (not easy)

Question 31

How to control BVD?

Answer 31

• PI culling
• vaccination
• biosecurity
• surveillance - milk/ ear notches

Question 32

What is Border disease?

Answer 32

• first detected 1959
• sheep and goats
• virus - tropism for foetal lymphoid tissue, hair follicles, CNS
• barron ewes, abortions, stillbirths
• lambs - tremor, abnormal conformation, weak, hairy fleeces
• PI lambs
• no vaccine