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18 Cards in this Set
- Front
- Back
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Define virus
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obligate intracellular pathogen that cannot generate its own energy and depends on the host cell's biochemical machinery for it's replication, transcription and translation.
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The capsid is composed of subunits known as _______.
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capsomeres
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Define virion
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the physical viral particle in the extra-cellular phase which is able to spread to new host cells
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What components make up a virus?
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DNA or RNA, structural proteins, enzymes, nucleic-acid binding proteins and envelope glycoproteins/membrane (sometimes)
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What is the function of the viral capsid?
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To protect the genome from nucleases and provide attachment to host cell
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Properties of naked capsid viruses
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Resistant to drying, heat, detergents, acids and proteases
This allows the virus to survive in the GI tract, retain infectivity on drying and spread easily by fomites. Must kill host cell to spread. |
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Properties of enveloped virus
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Sensitive to drying, heat, detergents and acid.
Must stay wet during transmission, cannot survive GI tract, does not need to kill cells to spread. |
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List the steps in a generic scheme of viral replication
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Recognition
attachment penetration or fusion uncoating transcription protein synthesis replication assembly or envelopment lysis or budding resulting in release |
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Naked viruses must lyse the host cell to be released (T/F)
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True
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Eclipse phase
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period in viral replication in which virus cannot be isolated due to disassembly within the cell
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Which viral samples should be collected WITHOUT transport media?
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blood, bone marrow, CSF, pleural fluid, amniotic fluid, urine and pericardial fluid
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Cytopathic effect
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degenerative changes in cells, especially in tissue culture, associated with the multiplication of certain viruses
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Electron microscopy is rarely used in clinical settings but can be used for _________.
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non-cultivatable viruses (i.e. Norwalk virus)
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Name 3 biological quantitative assays for viruses
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plaque assays, transformation, endpoint (lethal dose, infectious dose, etc.)
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Name 2 physical or biochemical quantitative assays for viruses
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Hemagglutination, direct EM particle count
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RNA viruses have _____ mutation rates compared to DNA viruses because ______
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high, viral RNA polymerases lack the proof-reading ability of DNA polymerases
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Parvovirus B19 is in what genus?
What does this virus cause? |
Erythrovirus
Erythema infectiosum (slapped cheek syndrome), in utero infections can result in stillbirth |
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Adenoviridae have what type of genome? what type of structure?
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dsDNA, icosahedral capsid nonenveloped
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