1. Viruses

2. Virus Characteristics
Virus – a tiny, nonliving particle that enters and reproduces inside a living cell.
Viruses can ONLY multiply when inside a living cell.
A Virus acts like a parasite!

3. The Shape of a Virus Viruses come in many different shapes.
Varicella-zoster – the virus that causes Chicken Pox
Bacteriophage – A virus that attacks bacteria.
Filovirus – the virus that causes Ebola
Mononegavirales – the virus that causes Rabies

4. The Size of a Virus Viruses are smaller than cells.
Scientists use Electron Microscopes to see them.
Viruses are smaller than bacteria.
A Cold Virus has a diameter 100 times smaller than that of a Strep Throat Bacteria.
Bacteria Virus

5. Parts of a Virus A Virus has 2 Parts: Protein Coat (protection)
Inner Core (holds DNA)
Lock-and-Key Action
The protein coat’s shape has to fit into specific proteins on the host’s cells.
Example: The Cold Virus only infect cells in the nose and throat.

6. How do Viruses Multiply?
Once a virus “fits” into the host cell, the genetic material inside the virus takes over the host cell.
When the cell multiplies, then the genetic material of the virus also multiplies.

7. Diseases caused by Viruses
Common Cold
Influenza (“Flu”)
Small Pox
Chicken Pox
Measles
Yellow Fever
Ebola
HIV/AIDs
Shingles
Polio
Mononucleosis (“Mono”)

8. Treatment and Prevention
Viral diseases cannot be treated with antibiotics like Bacterial diseases.
Viral diseases can only
be prevented with…
Vaccination - Dead or weakened
pathogens are deliberately injected
into a person’s body to produce
antibodies.

9. Vaccinations
When given a vaccination, the weakened virus usually does not make the person sick.
The weakened virus allows the person’s immune system to produce antibodies.
The antibodies “remember” the virus and they fight the virus off before you get sick.
This prevents a person from getting a disease when they are exposed to the virus later.

10. Decide what causes the diseases and if they should be treated or prevented.
Infectious Disease
Caused by Bacteria or Virus?
Treat with Antibiotic or Prevent with Vaccination?
Lyme Disease
Polio
Measles
Strep Throat
Influenza (Flu)

11. Decide what causes the diseases and if they should be treated or prevented.
Infectious Disease
Caused by Bacteria or Virus?
Treat with Antibiotic or Prevent with Vaccination?
Lyme Disease
 Bacteria
 Treat with Antibiotic
Polio
 Virus
 Prevent with Vaccination
Measles
Strep Throat
Influenza (Flu)