1. What human diseases can you name that are caused by viruses?

2. Did you name: The flu – INFLUENZA! Swine flu! HIV/AIDS? Smallpox?
Chicken pox/shingles?
Common Colds?
Hepatitis?
Measles?
Warts?

3. Mono
Smallpox
Shingles/
Chicken Pox
Warts
Measles

4. What is a virus?
A virus is a core of DNA or RNA surrounded by a protein coat (capsid).
DNA
CAPSID

5. Viruses come in different shapes
They infect animals, plants and bacteria
e.g. influenza, HIV and small pox
e.g. tobacco mosaic virus in plants
Bacteriophage

6. How are viruses named?
Named for the type of cells they infect or the disease they cause.
tobacco mosaic virus is found in tobacco;
bacteriophages infect bacteria
HIV (Human Immunodeficiency Virus) damages the human immune system

7. How does a virus infect?
Lytic – enters host cell & copies itself. Then causes the host cell to burst & spread the virus.
Lysogenic – virus puts its DNA into the host’s DNA (provirus) and it gets copied every time the host cell divides. The infection may show up years later, when infected cells enter the lytic cycle together e.g. HIV
Can only reproduce by infecting living things!

8. Viral Infection Cycles –

9. Retrovirus (backward virus)
Retrovirus - contains RNA instead of DNA
must copy nucleic acid backward (RNA to DNA) to function, using reverse transcriptase
All retroviruses must be lysogenic.
Example: HIV

10. Is a virus alive? They are NOT alive! Made of cells?
Can it reproduce without a host?
Do they all have DNA?
Do they maintain homeostasis?
They are NOT alive!

11. HIV Attacks immune system – no cure yet Develops into AIDS
Sep 2009 vaccine in Thailand reported 30% decrease in infection
Bone marrow transplant?
Develops into AIDS
Killed more than 25 million since 1981
Came from SIV in late 19th century

12. Small pox
Emerged in human populations about 10,000 BC. Evidence of smallpox on the mummified body of Pharaoh Ramses V of Egypt
1967 killed 2 million people
USA smallpox free in 1971, world smallpox free in 1980

13. Ways we defend ourselves
Non-specific defenses—not a one-to-one defense; can be physical or chemical
1st line—skin! Prevents pathogens from getting inside. Body secretions (sweat, tears, saliva, mucus, oil) also help chemically and physically
2nd line—inflammatory response—swelling, fever, non-specific white blood cells (macrophages)

14. Chemical Assistance
Outside the body: disinfectants and antiseptics—alcohol, iodine, bleach—for PREVENTION
Inside the body—antibiotics (only against living things!) such as penicillin, ampicillin, amoxicillin, cipro, tetracycline, streptomycin, etc. –for TREATMENT