VIRUSES CHAPTER 18 Part 1

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

VIRUS - an obligate intracellular parasite INFECTIOUS MONONUCLEOSIS

Wendell Stanley (1904 - 1971) first isolated TMV in 1935. 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

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

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

Various Shapes of Viruses

Viral Replication Lytic Cycle 1. Attachment 2. Injection 3. Replication 4. Assembly 5. Lysis

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

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

VIRUSES CHAPTER 18 Part 2

Edward Jenner - discovered a vaccine for smallpox

Smallpox Variola (Major & Minor) First virus to be studied in detail Edward Jenner - 1798 First vaccine - cowpox virus (vaccinia virus)

Child with 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.) Last case of smallpox

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

Enveloped Virus INFLUENZA VIRUS

Children with measles (uncommon today)

BACTERIOPHAGE E-Coli Bacteria

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

Temperate vs. Virulent Viruses

HERPES ZOSTER (“Shingles”)

HERPES VIRUS HERPES

Herpes I and II Complex Herpes I – Oral, mouth, sores and lips “cold sores, fever blisters.” Herpes II – Genital. Both can be spread even if sores are not present. Dormant to attacks (or outbreaks) can be brought on by: general illness, fatigue, physical or emotional stress, menstruation, trauma to area – sexual activity, immunosuppression due to chemotherapy, steroids, medications. Symptoms, diagnosed, treated, pain, cure.

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

Retrovirus Cycle

HIV / AIDS

Louis Pasteur - discovered a vaccine for rabies

PATHWAY OF RABIES VIRUS

Animal Rabies in U. S. 1999

Bozeman biology virus http://youtu.be/L8oHs7G_syI