1. CHARACTERISTICS OF VIRUSES

2. Are Viruses Living or Non-living?
Biologists consider viruses to be non-living because:
Are not cells
Do not grow or respond to their surroundings
Cannot make food, take in food, or produce wastes
Viruses do not respond to stimuli.
They can only multiply if in another living cell

3. What are Viruses? Definition-
Viruses are noncellular particles made up of genetic material and protein that can invade living cells.

4. Discovery of Viruses
Beijerinck (1897) coined the Latin name “virus” meaning poison

5. Tobacco Mosaic Virus
Wendell Stanley (1935) discovered viruses were made of nucleic acid and protein

6. Smallpox
Edward Jenner (1796) developed a smallpox vaccine using milder cowpox viruses
Smallpox has been eradicated in the world today

7. How Big is a Virus?
Viruses are very small – smaller than the smallest cell.

8. Characteristics Non living structures Non-cellular
Contain a protein coat called the capsid
Have a nucleic acid core containing DNA or RNA (one or the other - not both)
Capable of reproducing only when inside a HOST cell

9. Characteristics Some viruses are enclosed in an protective envelope
CAPSID
Some viruses are enclosed in an protective envelope
Some viruses may have spikes to help attach to the host cell
Most viruses infect only SPECIFIC host cells
DNA
ENVELOPE
SPIKES

10. Characteristics Viruses cause many common illnesses/ diseases
HIV VIRUS
EBOLA VIRUS
Outside of host cells, viruses are inactive
Viruses cause many common illnesses/ diseases
Some viruses may cause some cancers like leukemia
Characteristics
MEASLES

11. Characteristics Viruses cause many common illnesses diseases
Some viruses may cause some cancers like leukemia
MEASLES

12. What do Viruses look like?
Viruses are unusual and different from other things in nature.
Viruses come in a variety of shapes
Some may be helical shape like the Ebola virus
Some may be polyhedral shapes like the influenza virus
Others have more complex shapes like bacteriophages

13. Types of Viruses: Helical Viruses

14. Polyhedral Viruses

15. Complex Viruses

16. Viral Taxonomy Family names end in -viridae Genus names end in -virus
Viral species: A group of viruses sharing the same genetic information and ecological niche (host).
Common names are used for species
Subspecies are designated by a number

17. Used for Virus Identification
Morophology
RNA or DNA Virus
Do or do NOT have an envelope
Capsid shape
HOST they infect

18. Herpes Virus
SIMPLEX I and II

19. Adenovirus
COMMON COLD

20. Influenza Virus

21. Chickenpox Virus

22. Papillomavirus – Warts!

23. HOST SPECIFICITY All kingdoms can be infected by viruses
Viruses are kingdom specific but they may or may not be species specific
Spread is specific to the type of virus

24. PARASITISM Viruses are parasites.
A parasite is an organism that depends upon another living organism for its existence in such a way that it harms that organism.

25. Bacteriophages

26. Cylces Lysogenic Cycle Lytic Cylce Viral DNA
May stay inactive in host for long periods of time
Long lasting
Example Mono or chickenpox
Lytic Cylce
Short and can be over come
Example flu virus

27. Vaccine Is a weaken form of the virus
To expose your immune system to the virus which will allow your body to better fight off the virus when exposed to the full blow virus.

28. Vector Control
This is controlling the vectors that are carrying the virus.
Examples:
We stay home when sick, cover our mouth when we cough etc.
We control the mosquito population in order to control the West Nile virus

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Other Drug Treatments
Specific to certain viruses.
They don’t cure the virus but they can slow down and inhibit the multiplication of the virus.
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30. Reducing the Risk They can’t be treated but they can be prevented!
Cover mouth/nose when you sneeze of cough
Wash hands frequently
Avoid contact with the body fluids
Not foolproof but reduces the risks