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Repulsion of superinfecting virions:A Mechanism for Rapid Virus Spread
Speaker: Chien‐Sin ChenAdviser: Li‐Kwan Chang Ph.D.
Virginie Doceul, Michael Hollinshead, Lonneke van der Linden, Geoffrey L. SmithScience 327: 873‐6, 2010
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Vaccinia virus
• Poxviruses
• Variola virus (smallpox), cowpox virus, vaccinia virus
• Not presently be found in nature
http://en.wikipedia.org/wiki/Vaccinia
NH Acheson, Fundamentals of molecular virology, Wiley, 2007
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Genes of vaccinia virus• About 200 kb genome
• dsDNA
• Closely packed genes, without intron
• For its life cycle and against host immunity
NH Acheson, Fundamentals of molecular virology, Wiley, 2007
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Viccinia virus life cycle
• Replicate in cytoplasm exclusively
• Progress is controlled by transcription factors
• Viral factories: replication and assembly
• IMV, IEV, CEV, EEV
NH Acheson, Fundamentals of molecular virology, Wiley, 2007
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Vaccinia virus dissemination overcomes its replication kinetics
• Viral factories: 4‐6 hr
• Cross cells: 75 min
5 mm
3 days
EGFPA5L Viral factoriesFree virions
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• De novo synthesized virionsleaves through actinprojections (CEV induces actin polymerization)
S Cudmore et al., Nat 378: 636‐8, 1995
Actin‐based virions spread
S Cudmore et al., J Cell Sci 109:1739‐47, 1996
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Viccinia virus life cycle
• Replicate in cytoplasm exclusively
• Progress is controlled by transcription factors
• Viral factories: replication and assembly
• IMV, IEV, CEV, EEV
NH Acheson, Fundamentals of molecular virology, Wiley, 2007
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Early expression of A33 and A36 is important for vaccinia virus spread
A36R, A33R, B5R are surface proteins
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Summary
• Phenomenon:Vaccinia virus spreads rapidly than predicted
• Mechanism:Virions are propelled by actin tails until reaching uninfected cells
• Machineries:Early co‐expression of A33R and A36R is sufficient and necessary
• Significance:A novel mechanism and potential target for drugs design
Uninfected cells
At plaque edge
Infected and virions‐producing cells
Infected but virions‐nonproducing cells
progres
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