PESTIVIRUSES

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PESTIVIRUSES

• PETER H. RUSSELL, BVSc, PhD, FRCPath, MRCVS
• Department of Pathology and Infectious Diseases,
  The Royal Veterinary College,
• Royal College Street,
• London NW1 OTU.
• E-mail Web site

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LEARNING OBJECTIVESStudents should be able to

• identify how swine fever virus, bovine virus
  diarrhoea, and border disease of sheep are
  related but yet distinct with regard to
  antigens and pathogenicity.
• explain the pathogenesis of acute, chronic and
  mucosal disease and how immune tolerant viraemic
  animals affect epidemiology.
• describe the importance of bovine pestiviruses as
  reproductive pathogens.
• describe in outline how swine fever virus was
  eradicated and how bovine virus diarrhoea virus
  is controlled in the UK.

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CLASSICAL SWINE FEVER VIRUS

• Epidemiology CSFV had a worldwide distribution
  but has now been eradicated from ill Australia,
  NZ., USA and some European countries eg Denmark.
  It can survive in formites and pig meat eg
  sausage.

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CLASSICAL SWINE FEVER VIRUS

• Control Eradicated in UK in 1971 but a
  Chinese-like virus (as defined by phylogenetics)
  entered UK in 2000. It almost certainly entered
  via illegally imported pigs from EU. Previous
  control programme started in 1963 with crystal
  violet inactivated vaccine in 1960 followed by
  slaughter policy in 1963. In 1967, reported cases
  down to single figures.

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BORDER DISEASE VIRUS

• Pathogenesis

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BORDER DISEASE VIRUS

• Epidemiology

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BORDER DISEASE VIRUS

• Diagnosis Detection of antibody by ELISA or
  virus by virus isolation in cell culture or by
  antigen detection in ELISA are the common methods
  for BVD diagnosis. This is usually subsequent to
  clinical diagnosis of abortion and the birth of
  'hairy shaker' Iambs.

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BOVINE VIRUS DIARRHOEA VIRUS and MUCOSAL DISEASE
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BOVINE VIRUS DIARRHOEA VIRUS and MUCOSAL DISEASE

• The Virus

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BVDV

• non-cytopathogenic cytopathogenic

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BVDV Disease
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Severe Haemorrhagic Disease due to BVDV
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Transmission of BVDV
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Transplacental infection
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Persistently infected (PI) animals

• BVDV PI animals have certain characteristics

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Persistently infected (PI) animals

• BVDV PI animals have certain characteristics
• (cont.)

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Persistently infected (PI) animals

• (cont.)

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Mucosal Disease
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Mucosal Disease

• (cont.)

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The cause of mucosal disease

• BVDVnc infection

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The cause of mucosal disease

• Superinfection with BVDV c
• Homologous' to persisting virus

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Diagnosis
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Control
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SUMMARY

• Transplacental infections initiate events which
  have important pathological consequences for all
  three viruses.
• SFV is notifiable, but has been eradicated, and
  the most recent suspect cases have been due to
  BVD infecting pigs.
• Border Disease can cause serious losses in
  lambs in anyone year due to CNS damage and poor
  doers with hairy coats. It is advisable to
  eliminate carriers by getting rid of the entire
  crop of lambs that year .
• BVD is a primary enteric pathogen but also a
  major source of loss through reproductive
  abnormalities. The nc isolates are important in
  establishing persistently infected calves that
  are susceptible to secondary infection with the
  cytopathic isolates to initiate mucosal disease.
  Vaccination of cows before their first
  insemination is recommended.