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 1
Copyright © 2010 Pearson Education, Inc. Virion Structure Figure 13.2a Nucleic acid DNA or RNA Capsid Capsomeres Envelope Spikes 2
Copyright © 2010 Pearson Education, Inc. Figure 13.3 Morphology of an Enveloped Virus 3
Copyright © 2010 Pearson Education, Inc. Figure 13.16b Enveloped Viruses 4
Copyright © 2010 Pearson Education, Inc. Figure 13.4 Morphology of a Helical Virus 5
Copyright © 2010 Pearson Education, Inc. Figure 13.5 Morphology of a Complex Virus 6
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 7
Copyright © 2010 Pearson Education, Inc. Figure 13.7 Growing Viruses Animal viruses may be grown in living animals or in embryonated eggs 8
Copyright © 2010 Pearson Education, Inc. Virus Identification Cytopathic effects: Detectable c hanges 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 9
Copyright © 2010 Pearson Education, Inc. Figure 13.9 Virus Identification: Cytopathic Effect 10
Copyright © 2010 Pearson Education, Inc. Lytic Cycle of a T-Even Bacteriophage Figure
Copyright © 2010 Pearson Education, Inc. 4 Figure Lytic Cycle of a T-Even Bacteriophage 12
Copyright © 2010 Pearson Education, Inc. Figure The Lysogenic Cycle 13
Copyright © 2010 Pearson Education, Inc. Figure 13.14a Attachment, Entry, Uncoating By pinocytosis 14
Copyright © 2010 Pearson Education, Inc. Figure 13.14b Attachment, Entry, Uncoating By fusion 15
Copyright © 2010 Pearson Education, Inc. Figure Multiplication of DNA Virus 16
Copyright © 2010 Pearson Education, Inc. Figure 13.17a Sense Strand (+ Strand) RNA Virus 17
Copyright © 2010 Pearson Education, Inc. Figure 13.17b Antisense Strand (– Strand) RNA Virus 18
Copyright © 2010 Pearson Education, Inc. Figure 13.17c Double-Stranded RNA Virus 19
Copyright © 2010 Pearson Education, Inc. Figure Multiplication of a Retrovirus 20
Copyright © 2010 Pearson Education, Inc. Figure Release of an enveloped virus through ‘budding’ 21
Copyright © 2010 Pearson Education, Inc. 22
Copyright © 2010 Pearson Education, Inc. 23