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22 Cards in this Set
- Front
- Back
Virulence
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The capacity of a virus to cause disease
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Viral pathogenesis
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the process by which a viral infection leads to disease. The sum of the effects of virus replication and the immune response on the host.
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3 patterns of viral infection
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1. Acute
2. Chronic 3. Latent, Relapsing |
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Acute Infection
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-Self limited
-Often asymptomatic -Often RNA viruses -Interact with innate immune system -Often shut of host cell protein synthesis -Cytopathic in vitro (inclusions, syncytia, cell swelling, apoptosis) -Replicate quickly and kill the cell -ex: influenza, rhinovirus |
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Syncytia
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Cell fusion that can be caused by viral infection. Viral fusion proteins delivered to surface and the infected cells fuse together
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Viral infections triggers production of...
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Cytokines, interferon, TNF
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What induces the anti-viral state in neighboring cells
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INF (alpha and beta) released by infected cell
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Chronic Infections
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-Prolonged period of time, continuously or intermittently
-Often DNA virus -May or may not be cleared -Non-cytopathic -Evasion of host immune defenses -Do not kill cell -Symptoms often from immune response that kills infected cells -Encounter Adaptive immune system (and innate too) |
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3 mechanisms chronic infections use to evade adaptive immunity
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1. Mutate and evolve
2. Modify immune response 3. Establish a latent infection and wait for immune response to wane |
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Latent Infections are usually DNA or RNA viruses
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dna
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Main Routes of Transmission
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1. Respiratory (aerosolized droplets, saliva)
2. Ailementary tract (fecal/oral, non-enveloped) 3. Urogenital (sexually transmitted) 4. Skin, mucous membranes |
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Passive Viral Dissemination (types)
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1. Hematogenous spread
2. Lymphatic Spread |
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Viremia
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Presence of infectious virus particles in the blood
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Hematogenous spread
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virus enters the blood streams
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Active Viral Dissemination (types)
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1. Hitch ride on migratory cells (DC and HIV)
2. Viral Surfing- Attach to cell surface and induce cell to move virus to where it can enter 3. Trigger own internalization into the cell 4. Move within a cell via microtubules (retrograde/anterograde spread) 5. Movement from cell to cell via filopods, budding, and actin rockets |
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3 major ways that viruses cause disease
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1. Direct cytopathic effects
2. Immunopathology 3. Viral oncogenesis |
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Diseases of immuno pathology
4 classes |
1. cell mediated
2. antibody mediated 3. autoimmunity 4. immunosuppression |
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What % of human cancers arise from viruses. What % are liver and cervical
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20% and 70%
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Mechanisms for Virus Induced Tumorigenesis
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1. Targeting tumor supressors
2. Inappropriate expression of growth factors 3. Induction of chronic injury/inflammation (hep B) 4. Retroviruses can encode oncogenes 5. Inderectly by prolonged immunosupression |
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Which 2 HPV viral proteins are highly expressed in cervical cancer tissue
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E6- Degrades p53
E7- Inactivates pRB |
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Function of HPV E2 protein
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E2 inhibits the production of E6 and E7 proteins, which are related to cancer formation. E2 is often removed when the HPV genome is incorporated into the cellular genome
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Gardasil
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protects against type 16 and 18 (70% of cancer) and types 6 and 11 (90% of warts)
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