Porcine viral diseases 1 - Emily Flashcards
What are the 4 viruses most commonly seen in pigs?
-Rotavirus
-Transmissible gastroenteritis virus (TGEV, coronavirus)
-Porcine epidemic diarrhea virus (PEDV, coronavirus)
-Swine Delta coronavirus (SDCV)
Which type of virus only affects suckling piglets and weaners?
Rotavirus
Which viruses can affect pigs through all life stages?
TGEV (transmissible gastroenteritis virus)
PEDV (porcine endemic diarrhea virus)
Delta corona virus
What are the common clinical signs of viral infections in pigs?
-Watery diarrhea
-Dehydration
-Loss of appetite
-Mortality 60% in suckling pigs
What structure do the 4 common viruses attack in the GIT?
Mature enterocytes in the small intestine
What are the clinical manifestations of PEDV?
-Diarrhea and vomiting
-Dehydration and metabolic acidosis
What is the incubation period of PEDV?
3-4 days
How does PEDV affect the intestinal villi?
It makes them stunted with a thinner wall, making the lumen larger and nutrients are unable to be properly absorbed
What type of cells does PEDV target?
Mature enterocytes!!
What are gross lesions of a PEDV infection?
Liquid intestinal contents, thin-walled intestines
What laboratory diagnostics can be used for identification of PEDV?
-RT-PCR
-ELISA
-Immunohistochemistry
-Virus isolation
-Immunofluorescence
-Serum neutralization
What preventative measures are available for PEDV?
-Natural immunity through colostrum (protection from 4-13 days of age)
-Biosecurity
-Vaccination (none in Canada yet)
What are the clinical manifestations of SDCV?
-Diarrhea and vomiting
-Mortality in nursing pigs
-Outbreaks when piglets are 3-5 weeks old
What mutation does TGEV have in its S-protein sequence that determines whether its tropism is for the GIT or the respiratory tract?
A deletion of 225aa in a spike protein of the glycoprotein envelope. If TGEV has this mutation, it becomes Porcine Respiratory Coronavirus (PRCoV) and changes its tropism to the respiratory tract
What are clinical manifestations of TGEV?
-Vomiting
-Profuse watery yellow diarrhea
-Rapid weight loss
-Dehydration
How would you be able to distinguish rotavirus from a coronavirus?
The infected enterocytes will take up a different stain
What is Porcine Parvovirus (PPV)?
-ssDNA genome, non-enveloped
-Virus needs REPLICATING cell (crypt cells)
-Causes SMEDI syndrome
Which virus requires replicating cells?
Porcine parvovirus
What is SMEDI syndrome? (Pls remember this!!)
-Stillbirths
-Mummification
-Embryonic Death
-Infertility
Which virus causes SMEDI syndrome?
Porcine Parvovirus!!
How is PPV transmitted?
-Secretes virus in feces and other fluids during acute infection
-Sow to fetus transmission only in seronegative animals (naive animals that haven’t been exposed before)
How long does vertical transmission of PPV take?
12-18 days after the initial infection of dams by fecal-oral route
What are the proposed theories for how sow to fetus transmission of PPV occurs?
-Lymph or blood or other fluids
-Continuous
-Transport by immune cells (macrophages/monocytes)
Which virus replicates in intestinal crypt cells?
Porcine parvovirus
How can PPV be diagnosed in a sow?
-Females return to estrus for no apparent reason
-Delays in parturition
-Increased mummified fetuses and smaller litters
How is PPV detected in fetal tissues?
The viral antigen can be detected using immunofluorescence
What is the vaccine protocol for PPV?
A sow will initially have passive immunity form its mother for 22 weeks. Then it will need a 1st dose of the vaccine. A booster vaccine should be given at 28 weeks of age. The sow should be bred at 32 weeks of age and will have immunity to PPV so that the fetuses do not become infected.
What is pseudorabies?
Suid Herpesvirus (Aujeszky Disease Virus)
How is pseudorabies transmitted?
-Direct nose-to-nose contact
-Sexual contact
-Inhalation of droplets or aerosolized virus
-Inanimate objects
Where does primary replication of pseudorabies occur?
In the respiratory tract
How does the pseudorabies virus spread throughout the body?
Spreads through blood vessels and lymphatics and retrograde transfer through neurons
Where does pseudorabies virus establish latency?
In the trigeminal ganglia
Where does secondary replication of pseudorabies occur?
Starts in the lymph nodes, which then goes systemic in circulation and reaches the placenta where replication continues
What is the main clinical sign of pseudorabies in neonates/suckling pigs?
Neurological symptoms (inability to move or stand, posterior paralysis)
What are the clinical signs of pseudorabies in weaner and grower pigs?
-Respiratory signs (coughing, sneezing, laboured breathing)
What are the clinical signs of pseudorabies in adult pigs?
Mild signs, but may have reproductive problems similar to SMEDI or give birth to piglets who are weak and trembling and quickly die
What can pseudorabies cause in non-natural hosts?
Unstoppable pruritus (itch signals to the brain that cannot be shut off)
How can pseudorabies be diagnosed?
Lesions, clinical signs, immunohistochemistry for viral antigens
Can pseudorabies be treated?
No, because it is a herpesvirus it is lifelong and goes into latency periods
What is the main source of pseudorabies being transmitted into domestic pigs?
Feral pigs
What are methods of eradicating pseudorabies?
-Serologic surveillance
-Culling of reactors
-Biosecurity
-Vaccination
What is the biggest concern with swine influenza virus?
Its ability to become zoonotic and infect multiple species
How is swine influenza transmitted?
Through nasal discharge and aerosols
What receptors does swine influenza have?
Human and avian flu viruses
How can swine influenza be detected?
-Nasal/tonsillar swabs
-RT-PCR
-Culture
-Immunohistochemistry
-ELISA
-Haemagglutination inhibition test
What is the best method for controlling swine influenza?
Vaccination
