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22 Cards in this Set
- Front
- Back
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What are some laboratory methods we use for virus replication? |
1. Inject into embryonated chicken eggs 2. Cell culture |
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Which viruses do we inject into the chorioallantoic membrane? |
Pox virus Infectious laryngotracheitis virus |
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Which virus do we inject into the amniotic cavity? |
Influenza virus |
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Which viruses do we inject into the allantoic cavity? |
Influenza virus Infectious bronchitis virus Newcastle disease virus Avian adenovirus |
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What is CPE? What does it mean? |
Cytopathic effect - a virus is considered slow growing if CPE appears after 4-5 days in culture - a virus is considered rapid growing if CPE appears after 1 to 2 days in culture |
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What is a non-cytopathic virus? |
In vitro infection is productive but cell structure and functions are preserved - yet they produce disease in hosts |
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7 types of Cytopathic effects |
1. total destruction 2. subtotal destruction 3. focal degeneration 4. swelling and clumping 5. Foamy degeneration (vacuolization) 6. Inclusion bodies 7. Cell fusion |
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What is a total destruction CPE? |
All cells in the monlayer rapidly shrink, become dense (pyknosis) and detach from the plate within 72 hours example: enteroviruses |
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What is subtotal destruction CPE? |
Death of some but not all of the cells in the monolayer Examples: alpha viruses some picornaviruses some paramyxoviruses |
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What is focal degeneration CPE? |
Produce localized areas of infection due to direct cell-to-cell transfer of virus - produce plaques Examples: - herpes viruses - poxviruses |
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What is swelling and clumping CPE? |
Infected cells greatly enlarge and clump together in grape-like clusters example: adenovirus |
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What is foamy degeneration (vacuolization)? |
Due to production of large and/or numerous cytoplasmic vacuoles - difficult to visualize without staining Examples: - paramyxoviruses - pestiviruses |
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What are inclusion bodies? |
Represent viral protein or nucleic acid being synthesized, or where virions are being assembled, or areas of viral scarring - cannot be seen in live cell cultures - may be intranuclear or intracytoplasmic - may be eosinophilic (pink staning) or basophilic (blue-purple staining) |
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What is cell fusion? |
Also called syncytium or polykaryon formation Fusion of the plasma membranes of four or more cells to produce an enlarged cell with multiple nuclei Examples: paramyxoviruses Herpesviruses |
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How is cell fusion facilitated? |
These viruses have fusion proteins or glycoproteins that act as fusion proteins, that can cause neighbouring cell membranes to fuse and form syncytium |
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What is the stepwise viral spread in a host? |
Primary lesion (invasion, multiplication) -> Regional lymph node (multiplication) -> Blood stream (primary viremia) -> Primary target organs (multiplication, tissue damage) -> Blood stream (secondary viremia) -> Secondary target organs |
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Which viruses cause primary lesions only? |
Rotaviruses Papillomaviruses |
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Outcomes of a viral infection depend on: |
Ability to infect (viral receptors)
- viral virulence Ability to colonize the host Ability to avoid clearance/immune response Host resistance/susceptibility |
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What are the two outcomes of successful viral replication? |
Inflammatory response Direct injury (*both lead to tissue specific injury* |
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What is virus induced transformation? |
Some viruses have the potential to change a cell from a normal cell into a tumour cell They are called oncogenic viruses |
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Tumours result due to genetic changes in: |
Cell proliferation Cell differentiation Apoptosis/programmed cell death |
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Two groups of tumour genes: |
Proto-oncogenes promote growth Tumour suppressors genes control proto-oncogenes *changes in either or both leads to uncontrolled cell growth* |
