Circoviridae - Circovirus Flashcards

1
Q

Describe the physiological characteristics of circoviridae.

A

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)

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2
Q

What does Chicken infectious anemia virus have that are less obvious in the other circoviruses?

A

12 trumpet like structures

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3
Q

Where does replication occur?

A

Actively dividing cell nucleus

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4
Q

Are virions of circovirus stable?

A

Yes.

Reisting 60C for 30 minutes and pH of 3-9

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5
Q

What is Post-Weaning multi systemic wasting syndrome?

A

Caused by porcine circovirus 2

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6
Q

What is the host and age affected by PMWS?

A

Pigs

4-6 weeks or 2-3 weeks post weaning

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7
Q

Where does PMWS occur?

A

Worldwide

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8
Q

How is PMWS transmitted?

A

Fecal-oral (most common)
Found in all secretion
Transplacental (vertical transmission)
Fomites

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9
Q

What do the inclusion bodies of PMWS look like?

A

“Botryoid” (grape-like) intra-cytoplasmic inclusion bodies in virus infected macrophages.

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10
Q

What cells does PMWS target?

A

Cardiomyocytes, hepatocytes, and macrophages during fetal life.
Mainly monocytes in early post-natal life.

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11
Q

What is the pathogenesis of PMWS?

A

Lymphoid depletion and lymphopenial in peripheral blood.
Loss of B-cells and T-cells.
Inhibits IFN-alpha

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12
Q

What happens to pregnant sows infected with PMWS?

A

During the 1st and 2nd trimesters- fetal death and resorption or aborted fetuses with severe cardiac congestion.
3rd trimester - minimal effects on fetuses

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13
Q

What are the common clinical signs of PMWS?

A

lethargy, progressive weight loss, cough, dyspnoea, slow growth, lymphadenopathy, diarrhea, skin discoloration, congenital tremors, icterus

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14
Q

How does severe disease and more pronounced lesions with PMWS occur?

A

Confections with Porcine parvovirus, Porcine reproductive virus, Porcine respiratory virus, SIV, Mycoplasma hyopneumoniae, or a variety of bacteria.

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15
Q

How does enzootic pneumonia of swine occur?

A

Co-infection of PMWS with Mycoplasma hyopneumoniae

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16
Q

How is PMWS diagnosed?

A

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

17
Q

What types of vaccinations against PMWS are available?

A

Chimeric virus uses PCV-1 capsid to innoculate vs. PCV-2

Baculovirus-expressed vaccines vs. capsid of PCV-2

18
Q

What is the vaccination schedule for piglets?

A

1st dose at 3 weeks

2nd dose at 6 weeks

19
Q

What is the vaccination schedule for the pregnant sow?

A

2 and 5 weeks antepartum.

20
Q

What is porcine dermatitis and nephropathy syndrome (PDNS)?

A
  • Reported with older piglets
  • Associated with PCV2
  • Necrotizing; skin lesions, vasculits, fibrinous glomerulonephritis