Pestivirus Flashcards
What is the family and genus?
- family - flaviviridae
- genus - pestivirus
What are some of its features?
- single stranded
- +ve sense RNA virus
- enveloped
What viruses does it include?
- CSFV
- BVDV
- BDV
label
What is the pathogenesis?
- depends on virus
- targets WBCs, gut, resp system, vasculature, CNS (foetus)
- cross placenta - abortion, persistent infections
What happens if injected in early gestation?
- will get virus
- early embryonic death
- abortion
- no antibodies formed
What happens if infected in late gestation?
- still have antibodies
- so virus will be gone before born
What happens if infected after birth?
- has immune response needed
What is CSFV?
- classical swine fever
- highly contagious
- notifiabel in pigs and wild boars
- one serotype - different strains
- eradicated in Uk - 1966
- last outbreak - 2000
What countries is CSFV eradicated in?
- austrailia
- canada
- new zealand
- US
- most of western and central europe
Describe the transmission of CSFV
- 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
What type of virus is CSFV?
- 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
What is the pregnant carrier sow syndrome?
- if infected 0-50 days - abortion, stillbirths, mummification
- 50-70 days - persistent infected offspring - dont produce neutralising antibodies
- 70-114 - late onset CSF
Describe the pathogenesis of CSFV?
- tropism for vascular endothelial cells and phagocytic mononuclear cells
- cause vasculitis, thrombocytopenia, thrombosis of small vessels, DIC
What is this showing?
- signs of CSF
- haemorrhagic lymph nodes
- dead patches in spleen
- small haemorrhages in kidney
- button ulcers in gut
What are CSF clinical signs?
- 3 presentations:
- acutely fatal
- chronic
- late onset/ congenital
- if have septicaemia/ high temp - APHA
What biosecurity methods should be used for prevention of CSF?
- do not feed uncooked rubbish
- quarantine
- isolation
- no visitors
- PPE
- health records
- protect from wild pigs
What surveillance for CSF?
- serological, virulence, clinical
Where are vaccines used for CSF?
- only in endemic countries
- not in UK - cant see if theyve been naturally infected
- if found:
- slaughter, containment, movement restrictions
What is BVDV?
- 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
Acute disease -BVDV?
- 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
What are the outcomes of infections at different times during pregnancy for BVD?
- 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
What are the congenital malformations BVD?
- cerebellum hypoplasia
- alterations in cerebrum
- bone growth retardation
- lung growth retardation
- thymus growth retardation
- ataxia
- hair coat
- weak calves
- kidneys
- ocular lesions
What are BVD PIs?
- infected in 1st trimester - 90 days
- immunotolerant to infection
- reservoir
- susceptible to mucosal disease
What is mucosal disease?
- 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
What is this?
- mucosal disease
How do you diagnose BVD?
- virus - isolation - add to bovine cells - look for fluroescence - live virus
- genome - PCR
- antigens - ELISA - milk/ ear notches
- antibodies - seroconversion - milk/ ear notches
Which test should be used in acute infection?
- PCR
- could use antigen ELISA/ isolation
- couldnt use antibodies - need a couple of weeks to make antigens
What test should be used for a PI animal?
- Isolation
- PCR
- ELISA
What test should be used when bulk testing milk?
- ELISA
- Ab - seroconversion
- could use PCR and isolation (not easy)
How to control BVD?
- PI culling
- vaccination
- biosecurity
- surveillance - milk/ ear notches
What is Border disease?
- 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
