Final: Coronaviridae Flashcards
Structure of coronaviridae
Icosahedral internal core structure enclosing a helical nucleocapsid (Coronavirus) or a tightly coiled tubular nucleocapsid bent into a doughnut shape (Torovirus)
Definition of Transmissible Gastroenteritis (TGE) in pigs
Highly infectious viral disease of pigs characterized with vomiting, dehydration, diarrhea and high mortality in piglets. Older pigs are also susceptible, but often exhibit milder clinical signs
Classified as “OIE List B disease”
Etiology of TGE in pigs
Genus Coronavirus of the family Coronaviridae
What is the epidemic form of TGE?
When the virus is first introduced into a susceptible herd, and is observed most often in winter. Rapid spread, high morbidity and mortality in piglets
What is the endemic form of TGE?
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 and much lower mortality or morbidity
Has TGE been reported in the USA?
Yes
What is the mode of transmission for TGEV?
Not clear, but fecal-oral transmission appears to be a major route of transmission. Can also be spread by aerosol.
What is the pathogenesis of TGEV?
Normal intestinal villi -> (enter TGE virus) Villus atrophy results in malabsorption-> diarrhea
Normal intestinal vili-> blunting and fusion of intestinal vili -> marked villus atrophy and fusion
Transmissible Gastroenteritis (TGE) in pigs causes what?
Incubation period: 24-48 hours
Onset is sudden
Profuse diarrhea in piglets Vomiting Severe depression and dehydration Water, yellow-green stool with offensive odor Feces contain clots of undigested milk
Pigs with TGE will have distended intestines that will show what?
Translucent intestinal wall and fluid ingesta
What will be in the dilated stomach of pigs with TGE?
Undigested milk
T/F: Pigs with TGE will have bloated gut and there will be presence of gases and atrophy of intestinal villi
True
Porcine Epidemic Diarrhea (PED) is caused by what? Is PED related to TGE virus?
Coronavirus
No, even though the clinical signs are similar
How is PED spread? What does it cause?
Fecal-oral route
Acute outbreaks of severe diarrhea and vomiting
T/F: PED has had no effect in the US
False
It has spread quickly and has caused severe economic losses
What is the pathogenesis of porcine hemagglutination encephalomyelitis?
Infection -> replication in nasal mucosa -> replication in lungs, tonsils, small intestine -> spread via PNS to CNS -> replication in brain stem, cerebrum and cerebellum -> virus replication in ganglion distale vagi OR disturbance in gastric emptying -> vomiting and malnutrition (respectively) -> wasting
Can go from replication in the brain stem cerebrum and cerebellum straight to acute enchephalomyelitis
What disease is caused by Porcine hemagglutinating encephalomyelitis?
Vomiting and wasting disease in pigs
Virus + RBC = ?
Agglutination
What age group is most affected by wasting?
Usually piglets <4 week old
What age group is most effected by acute encephalomyelitis from vomiting and wasting disease?
Piglets <2 weeks old
The form of vomiting and wasting disease that piglets get depends on what?
Pathogenicity of strain, age and litter susceptibility
What are the two forms of Porcine hemagglutinating encephalomyelitis?
Vomiting and Wasting Disease (VWD) form
Encephalomyelitic form
What does Bovine Coronavirus infection cause in calves? When does infection usually occur?
Diarrhea (1 day to 3 months old, mostly 1-2 weeks)
More common during winder months
What are the two paths of pathogenesis that can occur for Bovine Coronavirus infection?
Carrier cow or sick calf -> healthy calf -> virus replicated in upper respiratory tract -> respiratory symptoms: rhinitis, tracheitis
Carrier cow or sick calf -> healthy calf -> virus replicates in small intestine (primarily) and large intestine -> atrophy of villi, destruction of crypt epithelium -> malabsorption, increased secretary function -> profuse diarrhea (frequent, major symptoms)
What are the two routes of admin for bovine coronavirus infection in calves?
Fecal-oral transmission
Aerosol (?)
What is the etiology of winder dysentery in cows?
Primary etiology is believed to be a Bovine coronavirus
What is the transmission of winter dysentery in cows?
Fecal-oral route
What are the clinical signs of winter dysentery in cows?
Sudden, explosive outbreak of diarrhea Short course, dark green-black colored feces Presence of blood flecks Dehydration Decline in milk production Some coughing
What is Feline infectious peritonitis (FIP)?
Highly fatal immune mediated disease of cats and wild felids, such as Cheetahs.
Triggered by systemic infection of cats with feline coronavirus (FCoV)
An enigmatic disease: its biology is poorly understood and prevention is difficult
Who is FIP transmitted?
Infected/transiently infected OR chronic carrier cat -> FCoV shed in feces -> gets into uninflected cats by fecal-oral route.
What are the routes of transmission for FIP?
Fecal-oral route
Inhalation
Transplacental transmission
What are the 4 outcomes for cats that get FCoV infection?
Resistance (5-10%)
Transient infection with mild diarrhea (70%)
Persistent carriers (5-10%)
FIP (1-3%)
What are the 3 outcomes of cell mediated immunity (CMI) that can occur with FIP infections?
Strong CMI response -> Prevent FIP
Weak CMI & strong humoral response -> effusive (wet) form of FIP -> peritonitis, pleuritis, vasculitis, intravascular coagulation, ascites, glomerulonephritis
Intermediate response -> non-effusive/dry form FIP -> small granulomas, ocular lesions, CNS involvement
Where does the virulent for of FCoV replicate?
Monocytes and macrophages
What is the immunological pathogenesis of Feline infectious peritonitis virus?
FIPV -> attaches FIPV receptor on the macrophage -> macrophage engulfs the virus -> activated infected macrophage -> interaction with T cells in lymphoid tissues or can cause a disseminated infection
Antibody-dependent enhancement of FIPV?
FIPV spike-specific antibody binds to FIPV -> this will form an antigen-antibody-complex -> activation of complement pathway -> vasculitis and edema -> effusive or wet form of FIPV
Antibodies can also enhance uptake and replication of FIPVs in macrophages
What are some things that can be seen with the wet/effusive form of FIPV
Distended abdomen Diffuse Fibrinous Peritonitis Ascites Pyogranulomatous foci on the serosal surface of the intestines Pyrogranulomas in the liver Serofibrinous pleuritis Abdominal viscera show pyrogranulomatous foci Pyrogranulomas on omentum Thoracic effusion
What can be seen with the non-effusive/dry form of FIPV?
Granulomatous inflammation and enlarged mesenteric lymph nodes Pyogranulomatous lesions (kidney) Granulomatous meningoencephalitis Granulomatous uveitis Keratin precipitates on the inner cornea
How do we diagnose FIPV?
Effusion analysis: Rivalta test
ELISA
IFA
Virus-neutralization
(All detect presence of coronavirus antibodies in a cat but cannot differentiate between the various strains of feline coronavirus)
What is the Rivalta test?
In a test tube, add one drop of 98% acetic acid + 5 mL distilled water and mix thoroughly. Add one drop of effusion to the 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.
Are vaccines available for FIPV?
Intranasal vaccine was developed to prevent FIP in cats but the vaccine is not recommended
What is avian infectious bronchitis
A common, highly contagious, acute and economically important viral disease of chicken caused by coronavirus infectious bronchitis virus (IBV)
Which protein of infectious bronchitis virus (IBV) is antigenically significant and a major inducer of protective immunity?
S protein
What is a protectotypes?
Some IBV serotypes are able to cross-protect against other IBV serotypes; these have become known as protectotypes. Useful in vaccines.
How are IBV classified?
Multiple genotypes
Variation in S protein ->
Antigenic variation -> multiple serotypes
What are the pathotypes of avian infectious bronchitis?
I. Respiratory II. Enteropathic III. Nephrotropic IV. Proventricular V. Uterotropic
Where is the pathology of avian infectious bronchitis commonly reserved?
Respiratory tract
BUT, Some strains are highly nephropathogenic
How is IBV transmitted?
Infected chicks or even recovered/carrier chickens are sources of IBV: coughing, virus in tracheo-bronchial exudate, virus in feces, virus on egg surface from oviduct -> healthy bird -> respiratory disease (most common), nephritis or reproductive disorders -> decline in egg production
What are the routes of transmission for IBV?
Aerosol/inhalation
Direct contract
Contact with contaminated poulty, litter, food, water, equipment or other fomites
IBV respiratory disease (infectious bronchitis) will have enhanced severity by immunosuppression, E. coli, or Mycoplasma infections. What clinical signs can be seen?
Depression, ruffled feathers Gasping, respiratory distress Dyspnea, tracheal rales Congestion, hemorrhages in the trachea Inflammation of trachea and bronchi, white caseous exudate in syrinx and primary bronchi
What are the clinical signs for infectious bronchitis viral nephritis?
Nephritis, kidney swollen, urolithiasis, ureter distended with white urates
Visceral gout, urates on liver, heart
What clinical signs do we see for chickens with reproductive disorders due to IBV?
Soft-shelled, misshapen, discoloured eggs
Albumen thin and watery, separation between thick and thin albumen absent
Involuted, flaccid ovarian follicles
Stunting, dwarfing of embryo
What type of vaccines are available for IBV?
Live: are used in meat type chickens and for the initial vaccination and primin of breeders and layers pullets
Inactivated: intended for use in layers and breeders
What is the shape of the torovirus nucleocapsid?
Doughnut
What does torovirus cause in mammals, primarily cattle?
Gastroenteritis
What is the mode of transmission for torovirus?
Fecal-oral route
Bovine virus, aka Breda virus causes what in young calves?
Profuse diarrhea
Porcine epidemic diarrhea has been reported in the USA
True
Birds infected with avian infectious bronchitis virus exhibit only clinical signs of respiratory disease
False
