4. Virus: A biological particle composed of nucleic acid and protein Intracellular Parasites: organism that must “live” inside a host What is a Virus?

5. Reproduce Have nucleic acid Adapt to surroundings Have organization Not made of cells or organelles Can’t reproduce on own Don’t metabolize energy Don’t perform cellular processes

6. 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) –Membrane Shapes vary

7. Bacteriophages (infect bacteria) are often studied –Replication is similar with many animal viruses

8. 1 st 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

9. 2 nd Step: Entry –Virus enzyme weakens cell membrane –Genetic material (DNA or RNA) enters host cell endocytosis

10. 3 rd Step: Replication –Virus DNA/RNA uses ribosomes to make virus proteins –Virus proteins created by transcription/ translation

11. 4 th Step: Assembly –New virus proteins are assembled in the cytoplasm

12. 5 th Step: Release –Virus enzyme causes cell membrane to burst –Viruses are released to find new host –Cycle repeats

13. 1 st step: Attachment = Same 2 nd Step: Entry = Same

14. 3 rd 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

15. 4 th Step: Assembly Same, except many new viruses are being assembled in many cells 5 th Step: Release Same, except many cells burst releasing many more viruses

16. Host cell DNA Pro- phage

22. Retroviruses RNA viruses Contains the enzyme Reverse Transcriptase Steps –1) Virus RNA enters host cell. –2) Cell’s ribosomes create virus DNA. –3) Virus DNA combines with cell DNA (becomes dormant). Cells divide as usual with virus in DNA. –4) Once active, normal steps of transcription/translation followed.

23. Adults and children estimated to be living with HIV/AIDS as of end 2001 Western Europe 560 000 North Africa & MiddleEast 440 000 North America 940 000 Caribbean 420 000 Sub-Saharan Africa 28.1 million South 6.1 million & South-East Asia 6.1 million Latin America 1.4 million Total: 40 million Eastern Europe & Central Asia 1 million Australia & New Zealand 15 000 East Asia & Pacific 1 million

24. Estimated adult and child deaths from HIV/AIDS during 2001 Sub-Saharan Africa 2.3 million East Asia & Pacific 35 000 Western Europe 6 800 North Africa & Middle East 30 000 Eastern Europe & Central Asia 23 000 South & South-East Asia 400 000 Australia & New Zealand120 North America 20 000 Caribbean 30 000 Latin America 80 000 Total: 3 million

25. The AIDS pandemic Adults and children living with HIV/AIDS, end 2002 North America 980,000 North America 980,000 Caribbean 440,000 Caribbean 440,000 Latin America 1,500,000 Latin America 1,500,000 North Africa & Middle East 550,000 North Africa & Middle East 550,000 Sub-Saharan Africa 29,400,000 Sub-Saharan Africa 29,400,000 East Asia & Pacific 1,200,000 East Asia & Pacific 1,200,000 S & SE Asia 6,000,000 S & SE Asia 6,000,000 Australia & New Zealand 15,000 Australia & New Zealand 15,000 Western Europe 570,000 Western Europe 570,000 Eastern Europe & Central Asia 1,200,000 Eastern Europe & Central Asia 1,200,000 3.4% 4.8% 5.6% 11.1% 13.2% 13.5% 15.8% 17.8% 20.8% 29.0% 2001-02 increase Source: UNAIDS

26. How is HIV contracted? High 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

27. What is AIDS? Acquired Immunodeficiency Syndrome AIDS results when: –1) Less then 200 T cells per 1mm ³ blood –2) Multiple symptoms/infections from HIV appear Therefore, the HIV virus causes the disease AIDS Gender of those living with HIV (2003) New Exposures to HIV (2006)

28. Female Transmission of HIV (2006) Male Transmission of HIV (2006) Want more stats? Go to the Centers for Disease Control’s Website http://www.cdc.gov/hiv/topics/surveillance/united_states.htm