1. The Virus

2. All Have:
1) Capsid: coat of protein that surrounds nucleic acid
2) Nucleic Acid: RNA or DNA
Some Have:
Tail Fibers: Used for attachment (not legs)
Shapes vary
Enveloped, helical, or polyhedral
Virus
Parts
capsid
DNA
tail sheath
tail fiber

3. Are viruses alive? No Yes Not made of cells or organelles
Can’t reproduce on own
Don’t metabolize energy
Don’t perform cellular processes
Reproduce
Have nucleic acid
Adapt to surroundings
Have organization

4. Viral Replication Bacteriophages (infect bacteria) are often studied
Replication is similar with many animal viruses
Two ways: Lytic cycle & lysogenic cycle
These two can intertwine, working together…

5. Viruses can enter cells different ways
Endocytosis
Fusing with cell membrane
Bacteriophages pierce cells, injecting genetic material.
colored SEM; magnifications:
large photo 25,000; inset 38,000x

6. The Lytic Cycle 1st Step: Attachment Virus lands on cell membrane
Virus attaches to a cell receptor
No attachment = No infection
Virus acts as a “key” to the receptor

7. The Lytic Cycle 2nd Step: Entry Virus enzyme weakens cell membrane
endocytosis
2nd Step: Entry
Virus enzyme weakens cell membrane
Genetic material (DNA or RNA) enters host cell

8. The Lytic Cycle 3rd Step: Replication
Virus DNA/RNA uses ribosomes to make virus proteins
Virus proteins created by transcription/ translation

9. The Lytic Cycle 4th Step: Assembly
New virus proteins are assembled in the cytoplasm

10. The Lytic Cycle 5th Step: Release
Virus enzyme causes cell membrane to burst
Viruses are released to find new host
Cycle repeats

11. The Lysogenic Cycle
1st step: Attachment = Same
2nd Step: Entry = Same

12. Lysogenic Cycle 3rd step: Replication
Virus DNA combines with cell DNA, and waits
Provirus = cell DNA + viral DNA
Cell divides by mitosis
Each new cell will contain the provirus

13. The Lysogenic Cycle
4th Step: Assembly Same, except many new viruses are being assembled in many cells
5th Step: Release Same, except many cells burst releasing many more viruses

14. How is HIV contracted? High risk activities: Low risk activities:
1) Sex (oral, vaginal, anal)
2) Sharing needles (tattoos, piercings, drugs)
Low risk activities:
3) Mother to child in womb
4) Breast milk
5) Blood transfusions (used to be higher, but sanitation is better now)

15. What is AIDS? Acquired Immunodeficiency Syndrome AIDS results when:
New Exposures to HIV (2006)
Gender of those living
with HIV (2003)
Acquired Immunodeficiency Syndrome
AIDS results when:
1) Less then 200 T cells per 1mm³ blood
2) Multiple symptoms/infections from HIV appear
Therefore, the HIV virus causes the disease AIDS

16. Female Transmission of HIV (2006) Male Transmission of HIV (2006)
Want more stats? Go to the Centers for Disease Control’s Website

17. AIDS Quilt
3ft x 6ft quilt panel
can be created as
a memorial tribute

18. AIDS Quilt
Panels from across
the world are
sewn together

19. Panels travel around the world to help remember and raise awareness
AIDS Quilt
Panels travel around the world to help
remember and raise awareness

20. AIDS Quilt
Over 44,000 panels
exist today