Circoviridae - Circovirus Flashcards
Describe the physiological characteristics of circoviridae.
17-22nm in diameter (small)
Single-stranded DNA genome (circovirus- ambisense DNA, gyrovirus- negative sense DNA)
Virions are 20-25nm, non-enveloped, spherical, with icosahedral symmetry (T=1)
What does Chicken infectious anemia virus have that are less obvious in the other circoviruses?
12 trumpet like structures
Where does replication occur?
Actively dividing cell nucleus
Are virions of circovirus stable?
Yes.
Reisting 60C for 30 minutes and pH of 3-9
What is Post-Weaning multi systemic wasting syndrome?
Caused by porcine circovirus 2
What is the host and age affected by PMWS?
Pigs
4-6 weeks or 2-3 weeks post weaning
Where does PMWS occur?
Worldwide
How is PMWS transmitted?
Fecal-oral (most common)
Found in all secretion
Transplacental (vertical transmission)
Fomites
What do the inclusion bodies of PMWS look like?
“Botryoid” (grape-like) intra-cytoplasmic inclusion bodies in virus infected macrophages.
What cells does PMWS target?
Cardiomyocytes, hepatocytes, and macrophages during fetal life.
Mainly monocytes in early post-natal life.
What is the pathogenesis of PMWS?
Lymphoid depletion and lymphopenial in peripheral blood.
Loss of B-cells and T-cells.
Inhibits IFN-alpha
What happens to pregnant sows infected with PMWS?
During the 1st and 2nd trimesters- fetal death and resorption or aborted fetuses with severe cardiac congestion.
3rd trimester - minimal effects on fetuses
What are the common clinical signs of PMWS?
lethargy, progressive weight loss, cough, dyspnoea, slow growth, lymphadenopathy, diarrhea, skin discoloration, congenital tremors, icterus
How does severe disease and more pronounced lesions with PMWS occur?
Confections with Porcine parvovirus, Porcine reproductive virus, Porcine respiratory virus, SIV, Mycoplasma hyopneumoniae, or a variety of bacteria.
How does enzootic pneumonia of swine occur?
Co-infection of PMWS with Mycoplasma hyopneumoniae
How is PMWS diagnosed?
Clinical signs
Samples of blood, tonsils, lymph nodes, spleen, ileum
Characteristic histopathology
Serological assays not much values– most pigs are seropositive
Detection of PCV-2 nucleic acids by PCR
What types of vaccinations against PMWS are available?
Chimeric virus uses PCV-1 capsid to innoculate vs. PCV-2
Baculovirus-expressed vaccines vs. capsid of PCV-2
What is the vaccination schedule for piglets?
1st dose at 3 weeks
2nd dose at 6 weeks
What is the vaccination schedule for the pregnant sow?
2 and 5 weeks antepartum.
What is porcine dermatitis and nephropathy syndrome (PDNS)?
- Reported with older piglets
- Associated with PCV2
- Necrotizing; skin lesions, vasculits, fibrinous glomerulonephritis
