Biology Today Third Edition Chapter 16 HIV and AIDS Copyright © 2004 by Garland Science Eli Minkoff Pam Baker

Chapter 16 HIV and AIDS A. Definitions and History AIDS T h cells clusters Koch’s postulate B. Viruses What are they? How do they reproduce? C. HIV infection Stages Symptoms Tests Treatment Prevention

AIDS Acquired not born with it ImmunoDeficiency immune system is weakened Syndrome wide range of symptoms

T h cells Produce IL-2 Needed by B-cell to make anitbodies Needed by T c cells

Figure 16.1

T h cells Destroyed in AIDS Lose T c cells and the ability to make antibodies Vulnerable to infection

History 1981Pneumocystis carnii cluster 1981Kaposi sarcoma cluster in homosexual males

History Kaposi’s sarcoma also seen in kidney transplant patients (taking immunosupressive drugs) 1982called AIDS All patients had low T h cells

History 1983French group found RT (reverse transcriptase from retrovirus) NIHgroup grew suspect virus Found antibodies in patients 1986named HIV (human immunodeficiency virus) Montagnier Gallo

Koch’s postulate (late 1800’s) To prove that a “microorganism” causes a disease you must demonstrate that:

Koch’s postulate (pg. 579, BT3) 1. The microorganism is found in all “people” with the disease. 2. The microorganism is not found in “healthy” people. 3. Microorganism must be isolated and grown in pure culture. 4. Injecting microorganism into a person should cause the disease…

Koch’s postulate Koch showed that different bacteria caused Anthrax and TB (Nobel prize) Proven ?

Koch’s postulate Does HIV cause AIDS ? Most agree Some still doubt

Does HIV cause AIDS ? Most agree Gallo’s criteria pg. 581 BT3

1. HIV (or it’s antibody) is found in the vast majority of patients with AIDS. 2. HIV is found in most people with ARC 3. HIV is a new virus, AIDS is a new disease 4. If HIV is found, AIDS is to; no HIV, no AIDS 5. HIV-contaminated blood spreads AIDS 6. T h cells are low in AIDS and are attacked by HIV 7. HIV is found in brains of AIDS patients who die of AIDS (dementia is a symptom)

What is a virus? Nucleic acid (DNA or RNA) Protein coat (and maybe envelope) How Small ? human cell1 meter bacteriafootball virusM&M

What is a virus? Nucleic acid (DNA or RNA) Protein coat (and maybe envelope) Are they alive? Cannot replicate on their own

Properties of Living Things Living things are organized Living things are metabolic Living things respond to stimuli Living things are homeostatic Living things grow (biosynthesis) Living things contain genetic material Living things reproduce Living things form populations

Figure 16.3

Figure 16.4

1.Virus attachment and 2.fusion 3.Retrovirus(RNA) Reverse transcriptase RNADNA 4.Insert into host DNA

5.Host transcribes viral mRNA 6.Make viral proteins etc 7.Assemble viruses 8.Release of viruses

Viruses Can not replicate on their own Must use another cells machinery to replicate Are they living?

Stages of Infection with HIV Initial infection flu-like symptoms antibodies produced HIV+ Asymptomatic phase months to years AIDS T h cells decline opportunistic infections

Figure 16.7

AIDS T h cell decline Opportunistic infections High fevers Night sweats General weakness Mental deterioration (dementia) Weight loss

HIV+ ? Most tests detect antibody made against HIV (weeks or months) ELISA test Western blot PCR $ $$ $$$

Figure 16.7

What does HIV+ mean? Can HIV- person be infected? Can HIV- person pass disease?

Treatments: Reverse transcription inhibitors Protease inhibitors Fusion blockers Combination therapy

Figure 16.8

Variable disease progression Will everyone who is infected with HIV get AIDS ? We don’t know 12 year study in San Francisco 65% with AIDS; 35%, not yet

Prevention (lowering risks) High risk behavior sharing body fluids Blood, semen, vaginal secretions sharing needles pregnancy (untreated)

Prevention (lowering risks) Moderate risk behavior using condoms during sex breast-feeding receiving blood transfusion accidental needle stick infected dental workers kissing, “deep”

Prevention (lowering risks) Low risk behavior sharing toothbrush/razor tatoos receiving saliva or tears oral sex

Prevention (lowering risks) No risk behavior shaking hands sharing toilet sharing eating utensils being sneezed on working in same room handling pets “shallow” kissing

Figure 16.9

Chapter 16 HIV and AIDS A. Definitions and History AIDS Th cells clusters Koch’s postulate B. Viruses What are they? How do they reproduce? C. HIV infection Stages Symptoms Tests Treatment Prevention

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