1. AIDS supplement

2. History of HIV Originated in Africa in the late 1950’s
S.1 Origin and prevalence of HIV
History of HIV
Originated in Africa in the late 1950’s
Originally found in nonhuman primates and may have mutated
First documented in the US in 1969
HIV was found to be the cause of AIDS in

3. Prevalence of HIV Pandemic proportions
S.1 Origin and prevalence of HIV
Prevalence of HIV
Pandemic proportions
~ 38.6 million people are living with HIV
At least 1% of adults has HIV
Most people living with HIV live in developing countries with the highest in India and South Africa

4. S.1 Origin and prevalence of HIV

5. S.1 Origin and prevalence of HIV

6. Phases of HIV infection
S.2 Phases of HIV infection
Phases of HIV infection
Category A:
Asymptomatic but highly infectious
CD4 count above 500 cells/mm3
Category B:
One or more related to an impaired immune system
CD4 count between cells/mm3
Category C:
At this point the person has AIDS in which they have one or more of the AIDS opportunistic infections that eventually is the cause of death
CD4 count has fallen below 200 cells/mm3

7. Phases of HIV infection
S.2 Phases of HIV infection
Phases of HIV infection

8. Structure of HIV Two single strands of RNA
S.3 HIV structure and life cycle
Structure of HIV
Two single strands of RNA
Enveloped with spikes (Gp120)
Carries 3 enzymes
Reverse transcriptase
Integrase
Protease

9. HIV life cycle/replication
S.3 HIV structure and life cycle
HIV life cycle/replication
Attachment: Gp120 binds to CD4 receptors
Fusion: HIV fuses with the cell membrane
Entry: uncoating occurs to release the RNA
Reverse transcriptase: RNA is transcribed into double-stranded DNA
Integration: new DNA becomes part of the host cell’s DNA in the nucleus (provirus)
Biosynthesis: produces more viral RNA and proteins
Assembly: assemble new parts into viral particles
Budding: viral particles bud from the cell membrane taking a piece with it that becomes the envelope
Transmission to a new host: passed to a new host

10. S.3 HIV structure and life cycle
HIV life cycle

11. Transmission and prevention of HIV
S.3 HIV structure and life cycle
Transmission and prevention of HIV
Transmission is through sexual contact, dirty needles, a blood transfusion or to a baby from their mother
Globally heterosexual sex is the most common mode of transmission
HIV is not passed through casual contact
Prevention is through abstinence, sex with only one uninfected partner and proper, consistent use of condoms

12. HIV testing and treatment
S.3 HIV structure and life cycle
HIV testing and treatment
HIV tests test for the presence of antibodies not the virus itself
Most people develop antibodies within 2-8 weeks of infection but it can take 3-6 months (consider this when being tested!)
Treatments:
Drug therapy: highly active antiretroviral therapy (HAART) used a combination of drugs to inhibit HIV replication
Vaccines: as of 2006, 27 vaccines are being tested in humans but results are not expected until 2010 but these will not be a cure

13. Science Focus: HIV vaccines
S.3 HIV structure and life cycle
Science Focus: HIV vaccines
Difficulties in producing a vaccine development:
HIV viruses locally and globally are genetically different
No vaccine so far is 100% effective and may only provide short-term protection
Concerns that the vaccine may increase the chances of getting the disease or even cause the disease
There is no ideal animal model for testing besides humans themselves

14. Bioethical Focus: AIDS
S.3 HIV structure and life cycle
Bioethical Focus: AIDS
Globally:
95% of people living with HIV live in developing countries
80% of deaths are people ages 20-50
50% of new HIV infections are in people ages 15-24
Estimated that by the end of 2005, 65 million people have been infected yet only 1 in 10 are aware of the infection
12 million orphans have been left behind
In the US:
3% of people living with HIV live in the US
For men:
Male-male sexual contact is the main mode of transmission in the US (65%) while heterosexual contact accounts for ~16%
For women:
Heterosexual contact accounts for 78% of HIV transmission
African Americans are the hardest hit ethnic group
About 1 million people living with HIV today and 25% do not know it