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46 Cards in this Set
- Front
- Back
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what forms do viruses come in?
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non-enveloped and enveoled
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what are the components of a virus?
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nucleic acid, protein capsid, and sometimes a lipid envelope
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what are the forms of structural organization of a virus?
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icosahedral symmetry, helical symmetry, complex symmetry
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what is important about the structural organization of a virus?
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viral capsids always contain many copies of just several viral proteins, efficient use of a limited genetic coding capacity, and allows symmetrical organization so proteins don't have to interact in too many different ways
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what are the features of icosahedral symmetry?
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axes of symmetry (5x, 3x, 2x), has 20 faces which meet at 12 vertices, most efficient possible arrangement that uses smallest unit to build shell, and most viruses use several proteins or multiple copies of a single protein to make a single 'face'
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what are the features of helical symmetry?
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cylindrical capsid surround nucleic acid, composed of many copies of one protein that form a chain coiled around nucleic acid, specific protein-protein interactions determine helix pitch and rod rigidity, and one axis of symmetry along length
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what is unique about animal viruses with helical symmetry
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all are enveloped
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what are the features of complex symmetry?
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complex! Not responsible for this info
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how are viruses classified?
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chemical, but can also be classified by disease type, transmission method, and species infected
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what properties are used for the physicochemical classification of viruses?
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virion morphology, properties of genome, properties of proteins, replication strategy, physical properties
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what are features of virion morphology in virus classification?
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size, shape, envelope, peplomers, symmetry
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what are the properties of genome in virus classification?
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DNA or RNA, single or double stranded, linear or circular, number of segments, size of genome, nucleotide sequence
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what are the properties of proteins in virus classification?
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number, size, function, amino acid sequence
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what are the properties of replication strategy in virus classification?
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transcription & translation characteristics, site of accumulation of viral proteins, site of assembly, site of maturation and release, and cytopathology
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what are the physical properties in virus classification?
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stability at various pH, temperature, cation concentration, solvents, detergents, and radiation
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what is the classification scheme for viruses?
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family (viridae), genus, virus, serotype, strain, isolate
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what determines chemical inactivation of viruses?
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viral structural elements
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what can control viral transmission?
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chemical disinfectants
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what is the primary determinant of chemical inactivation?
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enveloped viruses are more labile (more easily inactivated) than non enveloped
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what is the secondary determinant of chemical inactivation?
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viruses with an RNA genome are more labile than those with a DNA genome
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what determines the physica inactivation of viruses?
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not correlated with viral structural properties: all inactivated by autoclaving, many inactivated by drying, most inactivated by ultraviolet light
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what inactivates all viruses?
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autoclaving
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what inactivates many viruses?
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drying
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what inactivates most viruses?
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ultraviolet light
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what are some alternative groupings for virus families?
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enteric viruses, respiratory viruses, oncogenic viruses, arboviruses,
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what are the features of enteric viruses?
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usually fecal-oral transmission, replicate primarily in intestinal tract, usually remain localized to enteric tract
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what are examples of enteric viruses?
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reo, corona, picorna, adeno, calici
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what are the features of respiratory viruses?
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usually respiratory transmission or by fomites, replicate primarily in respiratory tract, usually localized to respiratory tract
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what are examples of respiratory viruses?
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orthomyxo, paramyxo, corona, adeno, picorna, calici
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what are the features of oncogenic viruses?
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acquired by close contact, injection and other modes, usually infect only specific target tissues, may transform host cells and progress to malignancy, and includes viruses experimentally or actually oncogenic
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what are examples of oncogenic viruses?
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herpes, adeno, papova, hepadna, retro
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what are the features of arboviruses?
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replicate in arthropod hosts, transmitted by bite to vertebrate host, generate viremia in blood, so transmitted back to arthropod by bite, etc
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what are examples of arboviruses?
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toga, flavi, bunya, reo, rhabdo, ASFV
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what terms did the word arbovirus come from?
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ARthropod-BOrne viruses
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how does viral replication occur?
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attachment, penetration, uncoating, biosynthesis, assembly, release
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how does attachment and absorption occur?
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viral attachment protein binds cell receptor (different viruses bind different cell receptors) via specific non covalent bonds with multiple copies of each binding to each other, with absorption resulting from a stable attachment
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what are cell receptors for?
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pupose other than virus binding, and not all cells have receptors for all viruses
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what is a critical determinant of tropism?
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viral attachment protein / cell receptor interaction
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what is tropism?
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selective viral replication in a particular cell or tissue type
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what type of tropism is there?
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cell-specific tropism & species-specific tropism
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what receptor do we identify in regards to viruses?
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the one with highest affinity
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what do antivirals do?
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block binding to block infection
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what type of anti-virals can be developed?
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anti-virus antibody, anti-cell antibody, excess soluble receptors
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what do anti-virus antibody antivirals do?
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excess antibodies to virus, block virus's proteins from cell receptors
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what do anti-cell antibody antivirals do?
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excess antibodies to receptors, block cell receptors to virus
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what do excess soluble receptors antivirals do?
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excess receptors which coat virus with receptors but bind normal ligands too
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