CORONAVIRUSES

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CORONAVIRUSES

• 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

• Compare the pathogenesis and epizootiology of
  enteric coronaviruses of calves and pigs.
• Discuss the diagnosis of and problems
  associated with the control of feline infectious
  peritonitis virus.
• Explain how infectious bronchitis virus of
  chickens is controlled.

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FAMILY CHARACTERISTICS
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TRANSMISSIBLE GASTROENTERITIS VIRUS (TGEV)

• DISEASE PATHOGENESIS

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TRANSMISSIBLE GASTROENTERITIS VIRUS (TGEV)

• HOST RANGE pigs

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TRANSMISSIBLE GASTROENTERITIS VIRUS (TGEV)

• EPIZOOTIOLOGY Faecal-oral transmission
  chronic carriers may harbour infection in the
  respiratory tract (TGEV replicates in the lung
  also). Common in the U.S. In Europe, sporadic
  outbreaks occur. In the UK, TGE is often absent
  for several years.

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TRANSMISSIBLE GASTROENTERITIS VIRUS (TGEV)

• DIAGNOSIS

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TRANSMISSIBLE GASTROENTERITIS VIRUS (TGEV)

• CONTROL

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PORCINE RESPIRATORY CORONAVIRUS

• (PRCV)

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BOVINE ENTERIC CORONAVIRUS

• DISEASE PATHOGENESIS Infects the small
  intestinal colonic enterocytes causing villus
  stunting and a malabsorption diarrhoea. Also
  infects respiratory tract. One of the pathogens
  found associated with calf scour.

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FELINE INFECTIOUS PERITONITIS (FIP)FIP is a
fatal disease which occurs in around one tenth of
cats infected with the feline coronavirus (FCoV).
Therefore most cats infected with FCoV do not
develop FIP.

• DISEASE A slow death. Some weeks, months or
  years after a localized primary infection with
  FCoV, cats who have failed to eliminate the virus
  can develop FIP.

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FELINE INFECTIOUS PERITONITIS (FIP)

• ANTIGENICITY The virus associated with FIP is
  indistinguishable antigenically from the common
  enteric FCoV.

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FELINE INFECTIOUS PERITONITIS (FIP)

• HOST RANGE Domestic wild cats.

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FELINE INFECTIOUS PERITONITIS (FIP)

• CONTROL
• A vaccine (Primucell) is available outside the
  UK. It will not protect cats already incubating
  FIP and kittens have to be isolated to prevent
  infection with FCoV before they are old enough to
  be vaccinated at 16 weeks. Problems with
  vaccination Antibodies do not protect from the
  disease and probably make it worse.

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INFECTIOUS BRONCHITIS VIRUS (IBV) of CHICKENS

• ANTIGENICITY At least 8 serotypes in two
  antigenic groups.

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INFECTIOUS BRONCHITIS VIRUS (IBV) of CHICKENS

• EPIZOOTIOLOGY World-wide infection.
  Transmission by infectious droplet inhalation or
  faecal/oral. Persistent infections may occur for
  several months following recovery.

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OTHER CORONAVIRUSES
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Summary

• The pathogenesis of the gastroenteritis caused
  by TGEV in pigs and BCV in calves is similar but
  TGEV is epizootic or enzootic in pigs while BCV
  is enzootic.
• Feline Infectious Peritonitis is a fatal disease
  of cats (effusive/non-effusive forms). Diagnosis
  is difficult no vaccines in the UK.
• Infectious Bronchitis Virus is controlled by
  aerosol vaccination of chicks with attenuated
  vaccines.