LIFE CYCLES OF VIRUSES

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LIFE CYCLES OF VIRUSES
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• VIRUSES CAN EXHIBIT TWO TYPES OF LIFE CYCLES.
• 1. THE LYTIC CYCLE
• 2. THE LYSOGENIC CYCLE
• SOME VIRUSES EXHIBIT ONLY THE LYTIC CYLE.
• SOME VIRUSES CAN EXHIBIT BOTH LYTIC AND LYSOGENIC
  CYCLES.

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THE LYTIC CYCLE
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ONE-STEP GROWTH CURVE
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THE LYSOGENIC CYCLE
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HOW ANIMAL VIRUSES ENTER ANIMAL CELLS
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• VARIETY OF ANIMAL VIRAL INFECTIONS - LYTIC OR
  LYSOGENIC VIRUSES?

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TRANSDUCTION
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HOW ARE ANIMAL VIRUSES CULTURED IN THE LABORATORY

• CLASSIFICATION OF MEDIA
• LIVING MEDIA AND NON-LIVING MEDIA

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CELL CULTURE
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HOW ARE CELL CULTURES GROWN?
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• CYTOPATHIC EFFECT - CPE
• SOME VIRUSES, WHEN THEY INFECT A CELL, CHANGE THE
  MORPHOLOGY OF THE CELL IN VERY SPECIFIC WAYS.

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ANTIVIRAL AGENTS

• GENERALIZATIONS
• AMANTADINE
• A VARIETY OF NUCLEOSIDE ANALOGS
• ACYCLOVIR, AZT, 3TC, DDI, DDC
• PROTEASE INHIBITORS
• INTERFERONS

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AMANTADINE
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AVARIETY OF NUCLEOSIDE ANALOGS
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PROTEASE INHIBITORS AND INTERFERONS
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HEPATITIS VIRUSES

• HAV 50
• HBV 30
• HCV 20
• MODE OF TRANSMISSION
• CHRONICITY - CHRONIC OR ACUTE INFECTION
• TREATMENT/VACCINE

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UNCONVENTIONAL INFECTIVE AGENTS

• VIROIDS - 1967
• SMALL CIRCULAR MOLECULES OF SINGLE STRANDED RNA
• BEST STUDIED VIROID CAUSES DISEASE IN POTATOES
• COMPOSED OF 359 NUCLEOTIDES
• 10X SMALLER THAN SMALLEST KNOWN VIRUS

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PRIONS

• INFECTIOUS SELF REPLICATING PROTEINS
• COMPOSED OF ABOUT 250 AMINO ACIDS
• 100X SMALLER THAN THE SMALLEST KNOWN VIRUS
• CAUSATIVE AGENT OF MAD COW DISEASE (BOVINE
  SPONGIFORM ENCEPHALOPATHY) AND TWO HUMAN DISEASES
• CREUTZFELDT - JAKOB DISEASE (CJD)
• KURU