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17 Cards in this Set
- Front
- Back
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Which viruses are 100% fatal?
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Rabies, hepatitis, encephalitis, pneumonia, AIDS. Because we dont have any treatments for them. Death is a dead end for the virus also
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Most common viral infection
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respiratory tract infections. GI is second most common (diarrhea)
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Most viruses are symptomatic?
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No. 90% are asymptomatic.
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Viral properties
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Obligate intracellular parasite; no enzymes for energy production; no synthetic machinery, DNA or RNA (ss or ds); capsid (made of capsomeres); enveloped or naked
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Purpose of Capsid
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protection of nucleic acid from denaturing; facilitative virus entry into a cell. it's a protein coat
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What is the envelop?
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A piece of cellular membrane, in addition to the capsid. Virus acquires it as it exits the cell
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In human's all helical viruses are...
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enveloped
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Viral replication steps
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1. Adsorption
2. Penetration 3. Uncoating 4. Biosynthesis 5. Maturation and Release |
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Viral attachment proteins
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are specific for a specific cellular receptor. Different receptor for each species of virus.
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Virus receptor determines
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1. Host/species range
2. Cell/tissue tropism 3. prevention vaccine) |
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The attachment protein of the virus
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is important for the ultimate manifestation of the disease, how severe it's going to be, and transmission. This is all part of the adsorption stage of viral replication
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Viropexis (endocytosis)
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for naked viruses
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Fusion
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for enveloped. since the envelop is similar in make up to the membrane of the cell.
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RNA biosynthesis happens in the
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cytoplasm where it associates with ribosomes for direct translation into proteins
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DNA biosynthesis happens in the
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nucleus for mRNA production by the cell
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Cell destruction
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a primary mechanism of tissue damage, which will eventually become symptoms of disease. However the IMMUNE RESPONSE is what really causes the cell destruction.
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Most effective viral immune evasion technique?
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Antigenic Variation (mutation); ex influenza, HIV
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