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Exploring Viruses: Characteristics, Origins, and Impact

Discover the intriguing world of viruses, from their origins with Wendell Stanley to the impact of vaccines like the one for smallpox by Edward Jenner. Learn about viral structures, replication cycles, and the diverse shapes of viruses, as well as the distinction between lytic and lysogenic cycles. Explore specific viruses such as polio, herpes, and HIV, and their significance in human health. Uncover the history and advancements in combating viral diseases like rabies. This comprehensive overview sheds light on the complex nature of viruses and their role in infectious diseases.

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Exploring Viruses: Characteristics, Origins, and Impact

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  1. VIRUSESCHAPTER 18 Part 1

  2. Characteristics T-4 Virus - infects E. coli • non-living particles • invade living cells • pathogenic - named after the disease they cause or organ they infect • smallest of all organisms

  3. VIRUS - an obligate intracellular parasite INFECTIOUS MONONUCLEOSIS

  4. Origin of Viruses Wendell Stanley (1904 - 1971) first isolated TMV in 1935. • Viruses may have originated from host cells • 1935 - first seen by an electron microscope • Tobacco mosaic virus - first virus discovered - 1886

  5. 1886 - “Living Fluid Infectant” - the virus passed through filters that held bacteria.

  6. Viral Structure • Inner core - contains viral DNA or RNA (never both) • Capsid - outer coat of protein • Envelope - outer layer on larger viruses

  7. Various Shapes of Viruses

  8. Viral ReplicationLytic Cycle • 1. Attachment • 2. Injection • 3. Replication • 4. Assembly • 5. Lysis

  9. LYSOGENIC CYCLE 1. Attachment 2. Injection • Viral DNA integration (provirus) 4. Cell division 5. Replication 6. Assembly 7. Lysis

  10. L Y S O G E N I C L Y T I C

  11. VIRUSESCHAPTER 18 Part 2

  12. Edward Jenner - discovered a vaccine for smallpox

  13. SmallpoxVariola (Major & Minor) • First virus to be studied in detail • Edward Jenner - 1798 • First vaccine - cowpox virus (vaccinia virus)

  14. Child with smallpox

  15. Last case of smallpox (Ali Maow of Merka, Somalia, contracted smallpox in 1977 at the age of 23. His was the last known case of smallpox in the world.)

  16. Icosahedral Virus(many sides) Wart virus Polio - Naked, small, icosahedral virus

  17. Enveloped Virus INFLUENZA VIRUS

  18. Children with measles (uncommon today)

  19. BACTERIOPHAGE E-Coli Bacteria

  20. Attachment of a phage to the cell wall of E-Coli

  21. Temperate vs. Virulent Viruses

  22. HERPES ZOSTER (“Shingles”)

  23. HERPESVIRUS HERPES

  24. Retroviruses HIV • RNA viruses • Reverse transcriptase - makes DNA from its RNA • Includes HIV, polio & some cancers

  25. Retrovirus Cycle

  26. HIV /AIDS

  27. Louis Pasteur -discovered a vaccine for rabies

  28. PATHWAY OF RABIES VIRUS

  29. Animal Rabies in U. S.1999

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