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Viro Second exam > Circoviridae > Flashcards

Circoviridae Flashcards

1
Q

what is the main disease we worry about with Circovirus in pigs?

A

Post weaning multisystemic wasting syndrom, PCT-2

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2
Q

Porcine circovirus type 1 is pathogenic?

A

FALSE NONPATHOGENIC

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3
Q

Genus Gyrovirus from the family Circoviridae is attributed to which disease in chickens?

A

Chicken infectious anemia virus.

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4
Q

General properties of Circoviridae

A

Small viruses 17-22nm in diameter, Viruses with circular single-stranded DNA genomes.

Non enveloped, spherical in outline with icosahedral symmetry T=1.

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5
Q

What is unique to Chicken infectious anemia virus in structure?

A

12 trumpet like structures that are less obvious in other circoviruses.

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6
Q

Genome of both Circovirus and Gyrovirus

A

Circovirus :circular SS ambisense DNA

Gyrovirus : Circular SS negative sense DNA

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7
Q

where does Viral DNA get replicated and what type of cells?

A

Replication occurs in actively dividing cells, and DNA replication occurs in the nucleus. S phase cell cycle provides cellular proteins and other components. Virions are very stable resisting 60 C for 30 min and pH 3 to pH9

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8
Q

Etiology of PMWS

A

Porcine circovirus 2 PCV2

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9
Q

Transmission of PCV2

A

wide spread in most pig populations

  • Fecal/oral transmission MOST COMMON
  • Virus found in ALL SECRETIONS, feces, urine, nasal secretions, saliva.
  • Vertical transmission (transplacental infection) occurs in swine. Virus is stable and can survive on Fomites for long periods.
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10
Q

Pathogenesis of PMWS

A

Characterized by individual to coalescing foci of granulomatous inflammation in lymphoid tissues, lungs, liver, kidney, heart and intestines, sometimes with prominent botryoid (grapelike ) intracytoplasmic inclusion bodies in virus infected macrophages.

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11
Q

What are the major cell types that PCV2 targets?

A

cardiomyocytes, hepatocytes, and macrophages during fetal life and mainly monocytes in early post natal life.

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12
Q

What is a consistent feature in pigs that develop clinical PMWS?

A

Lymphoid depletion and lymphopenia in peripheral blood. Loss of B and T cells , not direct effect of PCV2 on lymphocytes and how this lymphopenia is caused is unknown. Inhibitory effect on interferon alpha production by porcine leukocytes.

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13
Q

Transplacental infection results in what?

A

Infection during the first and second trimesters results in fetal death and resorption or aborted fetuses with severe cardiac congestion. infection during last trimester has minimal effect on fetuses.

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14
Q

Clinical signs, what is most common and what is the morbidity rates ?

A

subclinical infection is most common, with 10-30 % morbidity

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15
Q

Common clinical signs?

A

Lethargy, progressive weight loss, cough dyspnea, slow growth, lymphadenopathy, swollen inguinal lymph nodes, diarrhea, skin discoloration, congenital tremors, less commonly is icherus

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16
Q

Is co infection possible with PMWS?

A

Yes, with PPV, porcine reproductive and respiratory virus, SIV, mycoplasma hyopneumoniae, and variety of opportunistic bacteria may cause severe disease and more pronounced lesions.

17
Q

what do the lungs of a PMWS look like?

A

Rubbery lung, enlarged mandibular lymph nodes

18
Q

What about the liver and kidney in necropsy in a PMWS?

A

White necrotic foci in liver, Kidney: Multifocal necrosis.

19
Q

Co infection with PPV causes what?

A

Aborted fetus, mummies and stillborn fetuses.

20
Q

Co infection : Porcine Arterivirus PRRS

A

Interstitial pneumonia, aborted fetuses

21
Q

Co infection with Mycoplasma Hyopneumoniae in necropsy?

A

Enzootic pneumonia of swine, chronic bronchopneumonia.

22
Q

Diagnosis with PMWS:

A

Clinical signs, Samples: blood, tonsils, lymph nodes, spleen, ileum. Serological assays: Most pigs are seropostitive, therefore antigen detection is not of much value. Detection of PCV-2 nucleic acids by PCR.

23
Q

Vaccination in PMWS with Chimeric Vaccines

A

Chimeric Vaccines: New generation chimeric vaccines have been developed that utilize the non-pathogenic porcine circovirus 1 (PCV-1) as a genetic backbone for expression of the immunogenic capsid protein of PCV-2

24
Q

Inactivated or Baculovirus expressed vaccines:

A

Virus - like particles that include the capsid protein of PCV-2 are also available as vaccines.

25
Q

Sow vaccination:

A

2 and 5 weeks antepartum

26
Q

What disease is associated with PCV2, is sporadic and found in older piglets.

A

Porcine Dermatitis and Nephropathy Syndrome (PDNS). Findings: Necrotizing skin lesions, Necrotizing vasculitis, Necrotizing and fibrinous glomerulonephritis

27
Q

Genus Gyrovirus

A

Chicken Infectious Anemia, CAV, chicken anemia virus

28
Q

CAV disease effect on older chickens?

A

Older chickens are resistant to clinical disease. Highly contagious disease of young chickens (2-4 weeks of age).

29
Q

Transmission of CAV

A

Virus is shed in feces and feather dander, Horizontal transmission is through inhalation or oral exposure. Virus is also transmitted vertically through egg. Environmentally stable virus, remains in contaminated fomites for long periods.

30
Q

Pathogenesis of CAV is?

A

hemocytoblasts in the bone marrow, precursor T cells in the cortex of the thymus, and dividing CD4 and CD8 cells in the spleen. Replication in the hemocytoblasts leads to anemia, while replication in the T cells causes immunosuppression.

31
Q

what is apoptin? What does it cause?

A

apoptin protein of CAV induces apoptosis of infected lymphocytes. Immunosuppression and aplastic anemia, blood may be watery and clot slowly as a result of thrombocytopenia. Birds are vulnerable to secondary bacterial and fungal infections. Virus replication in oviduct of chicken may be regulated by estrogen allowing more efficient vertical transmission.

32
Q

Diagnosis of CAV

A

Clinical signs, (depression, lethargy, reduced body weight gain, pale, PCV low, SubQ hemorrhages and skeletal hemorrhages, pale muscles.
Necropsy, histopathology, Serology, Virus isolation, RT-PCR.

33
Q

Chicken Infectious Anemia Vaccination

A
  • Immunity to chicken anemia virus is complex,
  • presence of antibodies in breeders greatly reduces vertical as well as horizontal transmission.
  • the aim of vaccination is to protect the progeny from vaccinated breeders from early infections by means of maternally derived antibodies.
  • live vaccines are available for vaccination of antibody
  • Administration is by injection or by addition to the drinking water depending on the type of vaccine
  • Because of the synergism between CAv and other immunosuppressive viruses, such as Marek’s disease virus, control of the latter is also important

Viro Second exam (4 decks)

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