1. Viruses, Prions, and Viroids
(Oh my)

2. What is a virus? They are obligate intracellular parasites.
They contain either RNA (retrovirus) or DNA.
The have a protein coating and sometimes lipids.
They have the ability to take over the metabolic capabilities of cells in order to replicate and evolve.
Viruses are derived from their hosts and are more closely related to them, than to each other.

4. How do viruses replicate?
Viruses must use the host cell to replicate
Cannot replicate on their own because they’re not alive
Viruses can be lytic, lysogenic, or both

5. The Lytic Cycle
Invade cells and use the cell’s machinery to make more viruses
When the virus is done replicating it causes the host cells to “lyse” or burst and the new viruses emerge to invade new cells
Example: the common cold

7. The lysogenic cycle Lysogenic viruses keep their hosts alive.
The virus is able to combine it’s genetic material with that of the host.
Often the host cell will demonstrate notable differences (phage conversion).
Example: bacteriophages

9. Vaccines The creation of the vaccine:
Edward Jenner 1790
Cow pox vs. Small pox
Vacca = Vache = cow
1980 the World Health Organization (WHO) announced the eradication of small pox. The last case was in 1978.

10. Viroids “naked” genetic material Found in plants
Meaning what?
Found in plants
Cause errors in the regulatory system of plants

11. Prions Prions are parts of a protein- have no genetic material
Example: Mad Cow Disease, Sheep scrapie, Creutzfeldt-Jakob Disease- 9 total
All cause spongiform encephalopathies (large holes in the brain)
If prions don’t have nucleic acid how can they be a transmissible pathogen?