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Copyright © 2010 Pearson Education, Inc.
General Characteristics of Viruses Differentiate a virus from a bacterium.
Obligatory intracellular parasites Contain DNA or RNA simultaneously in the virion Contain a protein coat (capsid) Some are enclosed by an envelope Some viruses have spikes Most viruses infect only specific types of cells
in one host Host range is determined by specific host
attachment sites and cellular factors
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Copyright © 2010 Pearson Education, Inc.
Virion Structure
Figure 13.2a
Nucleic acid DNA or RNA
Capsid Capsomeres
Envelope Spikes
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Copyright © 2010 Pearson Education, Inc. Figure 13.6
Growing Viruses
Viruses must be grown in living cells Bacteriophages
form plaques on a lawn of bacteria
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Copyright © 2010 Pearson Education, Inc. Figure 13.7
Growing Viruses
Animal viruses may be grown in living animals or in embryonated eggs
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Virus Identification
Cytopathic effects: Detectable changes in the host cell due to viral infection (p. 441)
Blood serum (serology) tests Detect antibodies against viruses in a patient Use antibodies to identify viruses in neutralization tests,
viral hemagglutination, and Western blot
Nucleic acids: Studies of the DNA/RNA
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Lytic Cycle of a T-Even Bacteriophage
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Figure 13.11
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Copyright © 2010 Pearson Education, Inc. Figure 13.14a
Attachment, Entry, Uncoating
By pinocytosis
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Copyright © 2010 Pearson Education, Inc. Figure 13.20
Release of an enveloped virus through ‘budding’
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