Download WHAT THE HECK IS A VIRUS

Viruses
What is a virus?
How does a virus work?
How are viruses stopped?
WHAT IS A VIRUS?
NOT AN
INDEPENDENT LIVING
ORGANISM
VARIED IN SHAPE
 Enveloped (circular)
 Helical
West Nile Virus
 Polyhedral
VIRAL PARTS
Capsid- protein coat
Nucleic Acid
Membrane
(sometimes)

Surrounds capsid
Helps virus enter cell
How Viruses Replicate:
Lytic vs. Lysogenic
LYTIC CYCLE
TAKE OVER THE HOST
Replicate Viral DNA
 Destroy Host Cell

West Nile Virus
Lysogenic Cycle
“Hides” in host
 Replicates viral DNA, but does not destroy
cell
SARS Virus
HIV virus
Animations
Vaccinations
 First Developed by Edward Jenner
 Noticed milk maids DID NOT get smallpox
 Developed smallpox vaccine by exposing
patients to cowpox
 Allows patients to develop antibodies to
small pox virus
Vaccinations
Polio vaccine developed by Jonas Salk



Made the Polio virus inactive
Then exposed patients to inactive virus
Patients developed antibodies, but did not
get polio
Types of Viruses
Bacteriophages (infect bacteria/cells)


DNA based
Easier to deal with (usually)
Retroviruses and “others”


HIV
Influenza
HIV
Has RNA


RNA can mutate easily
Reverse Transcriptase (to make DNA)
Engulfed by white blood cells

(Does not inject)
Can remain “hidden” (lysogenic) for
long periods of time
Does not directly kill a person
Influenza
RNA
Engulfed by cells
Can kill, but usually just makes you
really sick
http://www.cssd11.k12.co.us/dohnts/Biology/bio04nt.htm
VIRAL DISEASES
Influenza
HIV
Polio
Polio
Small Pox
HIV
Ebola
Hantavirus
Hepatitis A-E
Influenza
SARS
Bird Flu
Common Cold
HPV
Can Viruses Be Good?
Possibilities in genetics

Fixing genes (Virus injects “good” DNA)
 Cystic Fibrosis
 Spinal Injuries…