Transcript HERPESVIRIDAE

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
LEARNING OBJECTIVES
Students 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.
FAMILY
CHARACTERISTICS:
TRANSMISSIBLE
GASTROENTERITIS VIRUS
(TGEV)
DISEASE & PATHOGENESIS
TRANSMISSIBLE
GASTROENTERITIS VIRUS
(TGEV)
HOST RANGE : pigs
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.
TRANSMISSIBLE
GASTROENTERITIS VIRUS
(TGEV)
DIAGNOSIS:
TRANSMISSIBLE
GASTROENTERITIS VIRUS
(TGEV)
CONTROL:
PORCINE RESPIRATORY
CORONAVIRUS
(PRCV)
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.
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.
FELINE INFECTIOUS
PERITONITIS (FIP)
ANTIGENICITY: The virus associated with
FIP is indistinguishable antigenically from the
common enteric FCoV.
FELINE INFECTIOUS
PERITONITIS (FIP)
HOST RANGE: Domestic & wild cats.
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.
INFECTIOUS BRONCHITIS
VIRUS (IBV) of CHICKENS
ANTIGENICITY : At least 8 serotypes in two
antigenic groups.
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.
OTHER CORONAVIRUSES
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.