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

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

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

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

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

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

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

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

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

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

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

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

Host cell DNA Pro- phage

Retroviruses RNA viruses Contains the enzyme Reverse Transcriptase Steps –1) Virus RNA enters host cell. –2) Virus reverse-transcribes viral RNA to DNA. –3) Virus DNA combines with cell DNA (becomes dormant). Cells divide normally. –4) Once active, normal steps of transcription/translation followed.

Adults and children estimated to be living with HIV/AIDS as of end 2001 Western Europe North Africa & MiddleEast North America Caribbean 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 East Asia & Pacific 1 million

Estimated adult and child deaths from HIV/AIDS during 2001 Sub-Saharan Africa 2.3 million East Asia & Pacific Western Europe North Africa & Middle East Eastern Europe & Central Asia South & South-East Asia Australia & New Zealand120 North America Caribbean Latin America Total: 3 million

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, % 4.8% 5.6% 11.1% 13.2% 13.5% 15.8% 17.8% 20.8% 29.0% increase Source: UNAIDS

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

What is AIDS? Acquired Immunodeficiency Syndrome AIDS results when: –1) Less then 200 T-cells per 1mm ³ blood –2) Multiple symptoms/infections appear because of HIV Rash, fever, headache, sore throat, swollen lymph nodes Therefore, the HIV virus causes the disease AIDS by killing your T-cells Gender of those living with HIV (2003) New Exposures to HIV (2006)

AIDS Patients are IMMUNOCOMPROMISED Who else might have a suppressed immune system?  Cancer patients (chemotherapy)  Organ transplant patients  Pregnant women  People who are malnourished (don’t eat)

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

1.All viruses have a protein capsid, nucleic acid, and tail fibers. 2.Phages are viruses that infect bacteria. 3.Some viruses can replicate in various bodily fluids. 4. In the lytic cycle, the virus DNA combines with the cell DNA and replicates with the cell. 5.In the Lysogenic cycle, the first step is virus attachment. 6.Retroviruses carry the enzyme Reverse Transcriptase. 7.Reverse Transcriptase converts DNA to RNA. 8.AIDS patients can infect others by coughing on them. 9.Organ transplant patients have an increased risk of developing infections.