1. WHAT IS A VIRUS?
A NONLIVING, NONCELLULAR PARTICLE MADE UP OF GENETIC MATERIAL AND PROTEIN

2. Inside head is genetic material Rest of virus is made of protein
Virus Structure
Inside head is genetic material
Rest of virus is made of protein

3. Viral Structure can Vary

4. SIZES OF VIRUSES 10-400 nm (1 nm is 1 billionth of a meter

5. Dimitri Iwanowski’s discovery

6. Viruses have SPECIFICITY
Specific VIRUSES INFECT specific ORGANISMS due to protein attraction
Host cell surface proteins & virus surface proteins
PLANT VIRUSES DO NOT INFECT ANIMALS
Rabies infect MAMMALS & SOME BIRDS
However viruses can mutate their genes to cross infect other organisms
swine flu, Ebola-bats to humans

7. Diagram in packet LIFE CYCLE OF LYTIC VIRUSES
LYTIC-CAUSES HOST cell to split and release replicated virus
1. INFECTION-VIRUS activated by contact with host cell surface proteins
2. INJECTS VIRAL GENETIC MATERIAL
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VIRAL REPRODUCTION CYCLE
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8. LIFE CYCLE CONTINUED
3. viral genes shut off infected cell’s genes so host cell immune system does not detect virus
4. REPLICATION-virus uses host cell materials to create copies of virus
5. LYSIS –host cell releases replicated virus

9. Lysogenic Virus Cycle Viral genetics combined with hosts

10. RETROVIRUSES example HIV
Virus has only RNA
RETRO-means backwards.
VIRUS produces DNA from RNA using the enzyme Reverse Transcriptase
Viral DNA is inserted into HOST cell immune cells (WBC’s) & new Viral copies are made

11. TRANSMISSION how virus’ are spread
INSECT BITE
BITE OF INFECTED ANIMAL
CONTAMINATED food, water, body fluids, needles, air, soil

12. SYMPTOMS RASH FEVER PARALYSIS HEADACHE ACHES SWOLLEN GLANDS CONGESTION
Runny nose

13. TREATING VIRUSES VACCINES
• CAN CONSIST OF LIVE altered VIRUSES or inactive viruses
• contain ANTIGENS (surface proteins) from the virus. They stimulate the immune system of organism to make Antibodies
• Vaccines can be given orally, inhaled or injected

14. VACCINE ANIMATION Creation of antibodies

15. TREATING VIRUSES Why do vaccines not always work?
A Virus can mutate its surface proteins. The organism’s immune system may not detect the changed protein and not attack it.
Example flu virus
Each year a new flu vaccine has to be made because of mutated proteins