Week 10

• Coronavirus group 1a

  Feline enteric coronavirus

  Canine coronavirus

  Transmissible gastroenteritis virus of swine

  Porcine respiratory coronavirus
• Coronavirus group 1b

  Porcine epidemic diarrhea virus
• Coronavirus group 2a

  Porcine hemagglutinating encephalomyelitis virus

  Mouse hepatitis virus

  Sialodacryoadenitis virus of rats

  Bovine coronavirus
• Coronavirus group 2b

  SARS coronavirus (humans)

  SARS coronavirus (civets, cats, bats)
• Coronavirus group 3

  Avian infectious bronchitis virus

  Turkey coronavirus (bluecomb virus)
• Coronavirus

  Icosahedral internal core structure enclosing helical nucleocapsid
• Torovirus

  Tightly coiled tubular nucleocapsid bent into a doughnut shape
• Transmissible gastroenteritis in pigs

  Highly infectious viral disease of pigs

  Vomiting, dehydration, diarrhea, high mortality in piglets

  Older pigs susceptible but exhibit milder clinical signs

  OIE list B disease

  Fecal-oral transmission
• Epidemic form of transmissible gastroenteritis in pigs

  When the virus is first introduced into a susceptible herd

  Observed mostly in winter

  Rapid spread, high morbidity and mortality in piglets
• Endemic form transmissible gastroenteritis in pigs

  Virus persists in partially immune herd or due to concurrent porcine respiratory coronavirus

  Less severe form of disease (much lower mortality or morbidity)
• Pathogenesis of transmissible gastroenteritis in pigs

  Villus atrophy - blunting and fusion of intestinal villi results in malabsorption

  24-48 hour incubation period

  Sudden onset
• Clinical signs from transmissible gastroenteritis in pigs

  Vomiting

  Severe dehydration and depression

  Watery, yellow-green stool with offensive odor

  Feces contain clots of undigested milk

  Distended intestine showing translucent intestinal wall and fluid ingesta, bloated gut

  Dilated stomach containing undigested milk

  Presence of gasses and atrophy intestinal villi
• Porcine epidemic diarrhea

  Fecal-oral transmission

  causes acute outbreaks of severe diarrhea and vomiting
• Porcine hemagglutinating encephalomyelitis (vomiting & wasting disease in pigs)

  Transmission - aerosol; contact with nasal secretions from infected or carrier swine

  Clinical forms - vomiting and wasting form; encephalomyelitic form
• Porcine hemagglutinating encephalomyelitis

  1.Replication in nasal mucosa

  2. Replication in lungs, tonsils, and small intestine

  3. Spread via peripheral nervous system to central nervous system

  4. Replication in brainstem, cerebrum, cerebellum - acute encephalomyelitis, virus replication in ganglion distale vagi, disturbance in gastric emptying
• Bovine coronavirus infection

  Transmission - fecal-oral; aerosols

  Site of replication - primarily in small intestine (also in large intestine) and also in upper respiratory tract

  Atropy of villi, destruction of crypt epithelium - malabsorption, increased secretory function, profuse diarrhea

  Respiratory symptoms - mild or subclinical; rhinitis, tracheitis (minor symptoms)
• Winter dystentery in cows (bovine coronavirus)


  Fecal-oral transmission

  Clinical signs - sudden, explosive outbreak of diarrhea, dehydration, decline in milk production, some coughing
• Feline infectious peritonitis

  Highly fatal immune mediated disease of cats and wild felids triggered by systemic infection of cats with feline coronavirus

  Enigmatic disease - biology poorly understood
• Feline infectious peritonitis transmission

  Fecal-oral - shed in feces from infected or transiently infected cat or chronic carrier

  Inhalation

  Transplacental
• Avirulent feline coronavirus mutate during replication in small intestine leading to avirulent/less virulent variants and FIP feline coronavirus
• Avirulent and virulent feline infectious peritonitis are simultaneously circulating in cat populations
• Feline infectious peritonitis pathogenesis

  Replicate in monocytes and macrophages, enters through CD13 receptor

  Infected activated macrophages spread throughout the body and release IL-10 to diminish cell mediated immunity

  Lose tropism for enterocytes of intestine
• Outcome of feline infectious peritonitis depends on how macrophages respond to viral infection and how the immune system of the host responds to the infected cells
• Strong cell mediated immunity 


  Prevent feline infectious peritonitis
• Weak cell mediated immunity and strong humoral response (effusive/wet form of feline infectious peritonitis)


  Peritonitis, pleuritis, ascites

  Vasculitis, intravascular coagulation, glomerulonephritis

  Distended abdomen, diffuse peritonitis

  Pyogranulomatous foci on the serosal surface of the intestines

  Pyogranulomatous liver, serofibrinous pleuritis, thoracic effusion

  Pyogranulomas on omentum

  Thoracic viscera show pyogranulomatous foci
• Intermediate cell mediated immunity and humoral response (non-effusive/dry form)


  Small granulomas, ocular lesions, CNS involvement

  Granulomatous inflammation and enlarged mesenteric lymph node

  Pyogranulomatous lesions (kidneys), granulomatous meningoencephalitis, granulomatous uveitis

  Keratic precipitate in the inner cornea
• Diagnosis of feline infectious peritonitis (Rivalta test)

  Add one drop 98% acetic acid and 5mL distilled water to a test tube

  Add one drop of effusion to tube

  If drop disappear and solution is clear = negative

  If drop retains shape, drops down or attached to surface of tube = positive
• ELISA, IFA, virus neutralization for FIP

  Detects presence of coronavirus antibodies in cat

  Can't differentiate between various strains of feline coronavirus
• FIP vaccine

  Intranasal vaccine was developed to prevent FIP in cats

  Not recommended
• Avian infectious bronchitis

  Common, highly contagious acute, economically important viral disease of chickens

  Reproductive disorders

  Decline in egg production
• Tropism of avian infectious bronchitis

  Respiratory

  Enterotropic

  Nephrotropic

  Proventricular

  Uterotropic
• Transmission of avian infectious bronchitis

  Aerosol/inhalation

  Direct contact

  Indirect contact through contaminated poultry, litter, food, water, equipment, or other fomites
• Bronchitis in avian infectious bronchitis

  Severity enhanced by immunosuppression, E. coli or Mycoplasma infection

  Depression, ruffled feathers

  Dyspnea, tracheal rales

  Congestion or hemorrhages in trachea

  Inflammation of trachea and bronchi with white caseous exudate in syrinx and primary bronchi
• Nephritis in avian infectious bronchitis

  Urolithiasis, ureter distended with urates

  White urates in swollen kidney

  Visceral gout, urates on liver and heart
• Reproductive disorders in avian infectious bronchitis

  Soft-shelled, misshapen, discolored eggs

  Albumen thin and watery, separation between thick and thin albumen

  Involuted flaccid ovarian follicles

  Stunting, dwarfing of embryo
• Avian infectious bronchitis vaccines

  Live vaccines for broilers and the initial vaccination and priming of breeders and layers pullets

  Inactivated vaccines intended for use in layers and breeders
• Bovine torovirus (Breda virus) 


  Causes profuse diarrhea in young calves

  Fecal-oral transmission

  Causes gastroenteritis
• Caliciviridae

  Vesivirus - Vesicular exanthema of swine and feline calicivirus

  Norovirus causes gastroenteritis
• Feline calicivirus

  Highly infectious pathogen of cats

  Associated with range of clinical syndromes (inapparent to typical mild or acute oral and upper respiratory tract disease)

  Some strains induce lameness

  Highly virulent forms have emerged and are associated with systemic infection that is frequently fatal
• Transmission of feline calicivirus

  Shed in oral, nasal, and conjunctival secretions

  Direct contact with conjunctiva

  Inhalation

  Ingestion