Family: Coronaviridae Flashcards
Coronavirus
Group 1a
What are the 4 viruses in this group?
- Feline enteric coronavirus
- formerly feline infectious peritonitis virus
- Canine coronavirus
- Transmissible gastroenteritis virus of swine
- Porcine respiratory coronavirus
Coronavirus
Group 1b
What is the virus in this group?
- Porcine epidemic diarrhea virus
Coronavirus
Group 2a
What are the 4 viruses in this group?
- Porcine hemagglutinating encephalomyelitis virus
- Mouse hepatitis virus
- Sialodacryoadenitis virus of rats
- Bovine coronavirus
Coronavirus
Group 2b
What are the 2 viruses in this group?
- SARS coronavirus (humans)
- SARS coronavirus (civet cats, bats)
Coronavirus
Group 3
What are the 2 viruses in this group?
- Avian infectious bronchitis virus
- Turkey coronavirus, Bluecomb virus
What are the 2 characteristic shapes of viruses found in Family Coronaviridae? How can you distinguish between the 2?
- Coronavirus have icosahedral internal core structure enclosing a helical nucelocapsid
- Torovirus have a tightly coiled tubular nucleocapsid bent intoa. doughnut shape
Transmissible Gastroenteritis (TGE) in Pigs
Coronavirus Group 1A
- highly infectious viral disease of pigs
- vomiting, dehydration, diarrhea, high mortality (piglets)
- older pigs susceptible, but have milder clinical signs
- Classified as OIE List B disease
- 2 forms: epidemic and endemic forms
- reported in USA
- exact mode of transmission not clear, BUT fecal-oral (major route of transmission); can also spread via aerosol
- incubation period: 24-48 hours
- onset SUDDEN
What are the 2 forms of TGE (Transmissible Gastroenteritis in Pigs)?
-
Epidemic form:
- when virus is first introduced into susceptible herd
- observed most often in winter
- rapid spread, high morbidity + mortality (piglets)
-
Endemic form:
- when virus persists in a partially immune herd OR due to concurrent porcine respiratory coronavirus (PRCV) infection (a deletion mutant of TGE virus)
- less severe form of disease + much lower mortality or morbidity
What is the pathogenesis pathway of TGEV (Transmissible Gastroenteritis in Pigs)?
- normal intestinal villi becomes infected with TGE
- blunting + fusion of intestinal villi results in marked villus atrophy and fusion
- Malabsorption
- Diarrhea
What are the clinical signs of TGE (Transmissible Gastroenteritis in Pigs)?
- profuse diarrhea (piglets)
- vomiting
- severe depression + dehydration
- watery, yellow-green stool with offensive odor
- feces contain clots of undigested milk
What are Post Mortem findings of TGE (Transmissible Gastroenteritis in Pigs)?
- distended intestine showing translucent intestinal wall and fluid ingesta
- dilated stomach containing undigested milk
- bloated gut
- presence of gases and atrophy of intestinal villi
Porcine Epidemic Diarrhea (PED)
Coronavirus Group 1b
- although clinical signs similar, PED virus unrelated to TGE virus (Group 1a)
- spread via fecal-oral route
- cause acute outbreaks of severe diarrhea, vomiting
- spread quickly across many US states - severe economic losses
Porcine Hemagglutinating Encephalomyelitis (Vomiting & Wasting Disease in Pigs)
- coronavirus with hemagglutinating properties
- spread via aerosol route - contact with nasal secretions from infected or carrier swine
-
PHE virus has 2 forms:
-
Vomiting and Wasting Disease (VWD) form
- usually piglets <4 weeks of age
-
encephalomyelitic form
- usually piglets <2 weeks
-
Vomiting and Wasting Disease (VWD) form
- form depends on pathogenicity of strain, age and litter susceptiblity
What is the pathogenicity process of Porcine Hemagglutinating Encephalomyelitis (Vomiting & Wasting Disease in Pigs)
- pig becomes infected via aerosol route from contact with nasal secretions from infected or carrier swine
- viral replication occurs in nasal mucosa
- viral replication further occurs in lungs, tonsils, small intestine
- virus spreads via peripheral nervous system to CNS
- replication in brain stem, cerebrum, cerebellum
- becomes Acute Encephalomyelitis (piglets <2 weeks) OR
- virus replication in Ganglion Distale vagi -> vomiting -> malnutrition -> wasting OR
- disturbance in gastric emptying (replication vagal ganglion, lesions in intramural plexi of stomach) -> malnutrition -> wasting
- Wasting usually in piglets <4 weeks of age
* Form depends on pathogenicity of strain, age & litter susceptibility
Bovine Coronavirus Infection in Calves
- diarrhea in calves (1 day to 3 months of ages, mostly 1-2 weeks)
- common during winter months
- spread via fecal-oral transmission, possibly aerosol by other sick calves or carrier cows (mostly mother)
- frequent, major symptoms: profuse diarrhea
- minor symptoms: respiratory symptoms (mild or sub-clinical rhinitis, tracheitis)
Bovine Coronavirus Infection in Calves
What is the pathogenicity process of Bovine Coronavirus Infection in Calves?
- calf becomes infected via fecal-oral transmission or aerosol from another sick calf or carrier cow (mostly mother)
- virus primarily replicates in small intestine, and also in large intestine
- causes atrophy of villi, destruction of crypt epithelium
- malabsorption, increased secretory function
- profuse diarrhea (frequent, major symptoms)
- virus also replicates in upper respiratory tract
- respiratory symptoms (mild or sub-clinical) rhinitis, tracheitis (minor symptoms)
Winter Dysentery in Cows
- primary etiology: a bovine Coronavirus
- mainly transmitted by fecal-oral route
- clinical signs:
- sudden, explosive outbreak of diarrhea, short course
- dark green to black colored feces, presence of blood flecks
- dehydration
- decline in milk production
- some coughing
Feline Infectious Peritonitis (FIP)
- a highly fatal immune-mediated disease of cats and wild felids (Cheetahs)
- triggered by systemic infection of cats with feline coronavirus (FCoV)
- enigmatic disease: biology poorly understood + prevention difficult
- FCoV shed in feces by infected or transiently infected cat or chronic carrier cat
- fecal-oral transmission (primary)
- FCoV can also be transmitted by other routes:
- inhalation
- transplacental transmission
- an intranasal vaccine was developed to prevent FIP in cats -> vaccine is not recommended
Feline Infectious Peritonitis (FIP)
What are the 2 hypotheses regarding FIP infections?
hypothesis-1:
- FCoV (FECV, feline eneteric corona virus) infects cat
- FCoV (FECV) (Avirulent/less virulent)
- mutations can result in:
- Avirulent/less virulent variants OR
- FIP FCoV (FIPV) (Virulent)
hypothesis-2:
- Avirulent and Virulent forms are simultaneously circulating in cat populations
Feline Infectious Peritonitis (FIP)
What are the different types of CMI: Cell-Mediated immune responses that can occur?
- Strong CMI Response
- prevent FIP
- Weak CMI & Strong Humoral Response
- effusive (wet) form FIP
- Peritonitis, pleuritis, vasculitis, intravascular coagulation, ascites, glomerulonephritis
- Intermediate response
- non-effusive/Dry form FIP
- small granulomas, ocular lesions, CNS involvement
Feline Infectious Peritonitis (FIP)
What is the pathogenicity process of FIP?
- virulent form of FCoV (FIPV) replicate efficiently in monocytes and macrophages
- ?????????????
Feline Infectious Peritonitis (FIP)
Effusive Form
What are the clinical signs?
- distended abdomen
- diffuse fibrinous peritonitis
- ascites
- pyogranulomatous foci on the serosal surface of the intestines
- pyogranulomas in liver
- serofibrinous pleuritis
- abdominal viscera show pyogranulomatous foci
- pyogranulomas on omentum
- thoracic effusion
Feline Infectious Peritonitis (FIP)
Non-effusive Form or Dry Form
What are the clinical signs of FIP?
- granulomatous inflammation & enlarged mesenteric lymph node
- pyogranulomatous lesions (kidney)
- granulomatous meningoencephalitis
- granulomatous uveitis
- keratic precipitates on the inner cornea
Feline Infectious Peritonitis (FIP)
How do you diagnose FIP?
- Effusion Analysis: Rivalta Test
- in a test tube, add one drop 98% acetic acid + 5 mL distilled water and mix thoroughly. Add one drop of effusion to tube
- if drop disappears and solution is clear -> NEGATIVE FOR FIP
- if drop retains its shape, drops down or attached to surface of tube -> POSITIVE FOR FIP
- in a test tube, add one drop 98% acetic acid + 5 mL distilled water and mix thoroughly. Add one drop of effusion to tube
- ELISA, IFA, and virus-neutralization tests
- detect the presence of coronavirus antibodies in a cat
- BUT, these tests cannot differentiate btwn the various strains of feline coronavirus
Avian Infectious Bronchitis
- common, highly contagious, acute, and economically important viral disease of chickens caused by coronavirus infectious bronchitis virus (IBV)
- The S protein of Infectous Bronchitis virus (IBV) is antigenically significant & a major inducer of protective immunity
- mutation + recombination of IBV can result in:
- genetic variation of gene encoding S protein which can result in:
- multiple genotypes OR
- variation in S protein which results in
- antigenic variation -> multiple serotypes
- some of these serotypes are protectotypes
- genetic variation of gene encoding S protein which can result in:
- protectotypes: some IBV serotypes are able to cross-protect against other IBV serotypes
- useful in vaccines
Avian Infectious Bronchitis (IVB)
What are the places IVB likes to cause pathogenesis?
- respiratory
- eneterotropic
- nephrotropic
- proventricular
- uterotropic
common IB strains reported in literature are:
- respiratory
- nephrotropic
pathology is commonly observed in respiratory tract. some strains are highly nephropathogenic.
Avian Infectious Bronchitis (IBV)
What type of vaccines are available to control IBV?
- live vaccines:
- used in meat type (broiler) chickens
- used for the initial vaccination and priming of breeders and layers pullets
- inactivated vaccines:
- intended for use in layers and breeders
Torovirus
- named after unique shape of nucleocapsid, doughnut-shaped
- causes gastroenteritis in mammals, primarily cattle
- transmitted via fecal-oral route
Bovine Torovirus
aka
Breda Virus
- causes profuse diarrhea in young calves
