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59 Cards in this Set
- Front
- Back
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Ivanovsky
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1892, TMV, porcelain filter
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Beijerinck
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1898, TMV = 'virus'
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Loeffler and Frosch
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1898, foot-and-mouth = virus in animals
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Twort
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1915, bacteriophage but didn't know was virus
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d'Herelle
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coined term 'bacteriophage' as virus
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Schlessinger
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1933, purified 1st virus, virus = 1/2 protein, 1/2 nucleic acid
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Stanley
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1935, purified TMV, electron microscopy 1st applied to viruses
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Bawden and Pirie
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1937, showed TMV was RNA virus
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Markham and Smith
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1949, turnip yellow mosaic virus
found 2 particles (1= nucleic acid (key to infection) and 1 = not) |
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Hershey and Chase
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1952, DNA (not protein) carry genetic info
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Fraenkel-Conrat and Singer
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1957, virus infections mirrored RNA (not protein), nucleic acid = genetic info and could cause infection alone
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Brenner, Jacob, and Meselson
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1959, viruses use host cell ribosomes to produce protein, virus hijack cell
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Degeneracy
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possible origin of viruses - nucleic acid from protocell that lost all functions
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Escape
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possible origin of viruses - after acciental transfer, nucleic acid in foreign cell survive, replicate, and escape
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Primordial soup
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possible origin of virus - never associated with cells
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Organisms culture (advantages/disadvantages)
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Embryonic (in egg) Disadvantage: mutate when harvesting
Advantage: best models natural infection, sometimes only feasible culture system Disadvantage: bioethical considerations, cost, individual variations |
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Organ culture (advantages/disadvatages)
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Advanage: one organism can yeild multiple organ models, similar to natural infection
Disadvantage: many cell types present, no homeostasis, technical difficulties in sustainability (not natural environment) |
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Cell culture (advantages/Disadvantages)
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Advantages: control environment, little intercell variation, lab convenience (grow quick)
Disadvantage: mutate so don't resemble original, least like natural environment |
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Uses of Cell culture
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study cytopathic effects (effects of virus on cell type); study viral biology (replication); test response to agents; test virility; viral plaque assay (infection)
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Serology
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use of antibodies to bind viruses
Application: ID, infectivity, quantification HA/HIA/ELISA/Flourescence microscopy |
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Hemagluttination Assay
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Serology
plate out equal number of RBC to each well, add virus - if enough virus then RBC will stick together Titer/concentration Virus ok until too much antibody added |
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Hemagluttination-Inhibition Assay
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Serology
add virus antibody to all wells, add virus, wait, add RBC Titer/ID Antibody protected until too much virus |
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ELISA (enzyme-linked immunosorbent assay)
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Serology
detection/quantification Add antibody, add antigen (bind to antibody if for that disease)(cause sandwich ELISA), enzyme added and bind, add marker |
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Genetic Technology
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PCR, sequencing method (determine gene code), computer programs (compare sequence)
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Microscopy without light
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Use electrons (shorter wavelength), high resolution, use dead specimens, no color
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Transmission electron microscopy
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best for of EM for biology, thinly cut specimen coated in metal, electrons pass through thinner areas readily
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Scanning EM
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most detail, electrons bounce of specimen not transmitted through
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Helical
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rod-shaped spiral, ex. TMV, usually plants, single capsomer type
Why helix? virus use non-symetrical shapes to house genetic materials, helix maximizes bonding with nucleic acid, max stability |
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Icosahedral
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sphere made of flat tiles, general bauplan for symmetry
Why? smaller gene/subunits better (economy) |
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Why icosahedral over dodecahedral?
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less number of faces with less tight corners (tighter packing at joints = increased energy don't want)
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Enveloped
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ex. influenza, helical(variety) or icosahedral(animals) inside, from host cell, layer of viral proteins between capsid and envelope (glycoproteins)
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Comples viruses - head-tail
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ex. bacteriophages, bacteria only, head = icosahedral and tail = helical
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Complex viruses - Poxviruses
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HUGE oval with studs, more nucleic acid, more complex, more genes, lots of layers
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Preferred Capsid arrangement of human pathogens
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Icosahedral (non-enveloped) and Helical enveloped = common
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Positive sense RNA
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identical to mRNA, can't reproduce mRNA from it
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Negative sense RNA
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complementary to mRNA, can produce mRNA directly from it
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Baltimore Scheme Class 1
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dsDNA
dsDNA as template dsDNA-mRNA-dsDNA Animals: Pox, mono, HPV Plants: none |
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Baltimore Scheme Class 2
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ssDNA
ssDNA-dsDNA-mRNA-ssDNA ssDNA template (dsDNA as intermediate) Animals: fifth disease Plants: bean golden mosaic virus |
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Baltimore Scheme Class 7
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partial dsDNA
pdsDNA-mRNA-pdsDNA RNA as intermediate (positive sense) mRNA as template for replication (not original) Always in circular form Animals: Hep B Plants: cauliflower mosaic virus |
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Baltimore Scheme Class 3
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dsRNA with RDRP carry in
dsRNA-mRNA-dsRNA mRNA as template Animals: rotavirus Plants: white clover cryptic virus |
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Baltimore Scheme Class 4
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ssRNA, positive sense
ssRNA-dsRNA-mRNA-ssRNA dsRNA as template original strand must be converted to negative strand before mRNA generated pdsRNA as intermediate makes RDRP (not carry in) Animals:Norwalk, west nile, yellow fever Plants: TMV, many! |
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Baltimore Scheme Class 5
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ssRNA, negative sense (RDRP)
ssRNA-dsRNA-mRNA-ssRNA mRNA generated straight from original strand pdsRNA as intermediate Animals: ebola, influenza, measles Plants:tomato spotted wilt virus, potato yellow dwarf virus |
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Baltimore Scheme Class 6
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ssRNA
ssRNA-dsDNA-mRNA-ssRNA dsDNA as intermediate and template Animals: retrovirus, HIV Plants: none |
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ORF (open reading frame)
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cadence in which nucleic acid is read, gene can encode for more than one proteinm max of 6 per protein (most seen = 4)
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Satellites
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Ex. Hep D (delta agent) need Hep B (helper)
Stapler (helper) needs staples (satellites) satellite viruses encode their own protein, satellite nucleic acids do not have own protein ('naked') |
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Viroids
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only in plants, usually ssRNA, circular, complementary (nucleic acid can fold back on itself), no protein just nucleic acid, short
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Direct repetition on end
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same sequence on 5' and 3' end if read in same direction (ABC.....ABC)
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Indirect repitition on end
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same sequence if you read 5 to 3 and 3 to 5 (ABC.....CBA)
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concatemers
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ex. T4 phage, tandem repeats of genome that not seperate, individual nucleic acids are cleaved randomly
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point mutations
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change in letter, switch one for another, changes in genetic sequence, more common in RNA
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recombination mutations
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'viral sex', swapping of genetic info, equally common, recombination in segmented RNA genomes = reassortment
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Measles
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Class V: Paramyxoviridae, pathogenizes only humans
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Black
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Black's island data - correlations between population size and sustainability of measles, need 500,000 or measles die out (start in Mesopotamia 6000 years ago)
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Influenza
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Class V: Orthomyxoviridae, 3 genra (A,B,C) - A = severe in humans but in mostly animals, C least sever and in humans
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Antigenic drift
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point mutations (change in H and N), localized epidemics, immune individuals drive drift - must mutate so survive
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antigenic shift
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rare and major change in H and N, reassortment, global pandemic
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Ebola and Marburg
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Emerging Viral Disease, Class V: Filoviridae
don't know reservior, no treatment |
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West Nile
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emerging viral disease
Class IV: Flaviviridae no treatment, birds/mosquitos are host |
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Multiple Sclerosis
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Myelin-specific CD4+T cells attack oligodendrocytes (which protect myelin sheath)
Cause: HHV? - guilty-by-association |
