Viruses- • Particles of nucleic acid, protein, & some lipids • Any of the microscopic particles that invade cells of plants, animals, fungi, & bacteria. • Often destroying the host cell. • Parasite • Virus= poison (Latin) • Examples: Colds, flu, and HIV
Inside A Virus• A core of genetic material• Capsid= A protein coat –Enables a virus to invade it’s host. –May be: • DNA • RNA
Living or Non-Living • Living- • Non-Living – Have DNA & – Crystallize RNA – Not cells – Heredity – Can’t make – Reproduce proteins – Evolve – Can’t reproduce w/out a host.
Structure Of A Virus • Core- –Nucleic acid –(DNA or RNA) • Capsid- –Protein coat surrounds core
Diseases Caused by Viruses • AIDS, Measles, Influenza • Pathogenic viruses are transmitted from host to host. –Air: Chicken pox –Water: Hepatitis –Insects: West Nile –See page 489
Fighting Viruses • Antibiotics can’t fight viruses • Drugs can’t destroy the virus w/out destroying the host • Viruses are fought with prevention using vaccines.
Vaccination • Only a healthy immune system can fight most viral diseases. • Vaccines build up immunity
Great Triumph’s • Eliminating small pox • 1796 vaccine discovered • 1949 last case in US • 1977 last case of small pox outside of
Filoviruses • Viruses that live without causing apparent harm • Causes disease only when infecting other animals • Among the most dangerous viruses
Filoviruses- cont • Cause –Hemorrhagic fever –Attack connective tissue –Massive bleeding –Morality rate 30- 90% –Ex: Ebola (1995) out break in Zaire
Vaccines DO NOT Protect AgainstAll Viral Diseases. • Vaccines are only effective against viruses w/non varying proteins on their surfaces. • Small pox, measles, & polio (same) • HIV, Cold, Flu (mutate)
Lysogenic Infections • Invades host & viral genetic material is injected & then fuses w/ host’s genetic material. • Results in many cells being infected with viral nucleic acid. • This type of virus has a “dormant period” • HIV is a Lysogenic virus.
Lytic Infections • A virus enters a cell, makes copies of itself, and causes the cell to lysis. • Lysis= spreads the virus to other cells. • The cell can no longer tell its DNA from the virus’s DNA • Example Bacteriophage T4
Back To HIV (Lysogenic Virus) • How is it contracted – Sex (most common) – Blood transmissions/products – Drug use – Tattoos/piercings – Birth/breastfeeding – Healthcare settings
Preventing HIV (LIFE SKILL) • Abstinence or safe sex • Avoid drug & Alcohol use • Use caution in healthcare settings • Use caution when blood or other body fluids are spilled.