1. Chapter 2: The Path from HIV to AIDS

2. The Path from HIV to AIDS
HIV infects only humans and creates a deficiency in the body’s immune system
HIV belongs to a family of viruses called retroviruses
Because retroviruses mutate very quickly, a person’s immune system does not have any defenses against the new version of the virus
HIV is also a lentivirus – a virus with a long delay between initial infection and the time the infected person starts to show symptoms

3. The Structure of HIV-1
The Spikes: The complex proteins that protrude through the surface of the viral envelope
The Capsid: The bullet shaped core of the HIV particle which surrounds two single strands of HIV’s genetic material
Reverse Transcriptase: An enzyme that allows HIV’s RNA to change into DNA so that it can pass into the host cell’s nucleus to begin reproducing itself
The Viral Envelope: The outer coat of the virus, which is composed of two layers of fat molecules

4. What Happens After HIV Infects Cells?
Once in the body, HIV replicates and spreads widely
2-4 weeks after exposure, most HIV-infected people suffer flu-like symptoms, as
their immune systems fight off the initial HIV infection
This first immune response may dramatically reduce HIV levels
As a result, the number of CD4+ T-cells in a person’s body may rebound after the first, acute infection

5. What Happens After HIV Infects Cells? (continued)
The HIV+ person may then remain free of HIV-related symptoms for years
The virus continues replicating
Eventually, HIV overwhelms the person’s system and large quantities of the virus enter the blood stream

6. Why do HIV Infections Almost Always Progress to AIDS?
HIV eludes the immune system so that the body stops fighting it
HIV’s many mutations make some of its particles invisible to the body’s immune system
HIV damages the immune system, so that the body can’t fight it
Not enough healthy CD4+ cells to defend the body against infections
When the immune system can no longer defend against opportunistic infections, the person has AIDS

7. Diagnosing HIV Infection
Main Types of HIV Tests:
ELISA (Enzyme-Linked Immunosorbent Assay): determines if HIV antibodies are present in blood or oral fluids
Western Blot: A highly specific test that is used for confirming the ELISA test
Rapid HIV tests: Saliva-, urine-, and home HIV antibody testing kits
HIV RNA tests: Diagnose HIV infection very early, before antibodies are even formed

8. The Stages and Symptoms of HIV Disease
Primary Infection:
The first stage of HIV disease
2 to 4 weeks after infection, 87% of HIV+ persons suffer flu-like symptoms (acute HIV syndrome)
It usually takes 6 to 12 weeks for the immune system to develop antibodies to fight the virus
Seroconversion is the time when the body begins producing antibodies, this can take up to 6 months

9. The Stages and Symptoms of HIV Disease
Chronic HIV Infection:
Asymptomatic Period
Also called clinical latency – person has no signs or symptoms of HIV disease
Although individual shows no symptoms, the virus is actively multiplying and infecting and killing immune system cells
Immune System Decline
The more HIV a person has (the plasma viral load) the lower the number of CD4+ cells; ultimately results in the rapid decline of the immune system

10. Mild, Non-specific Symptoms:
Immune System Decline
Mild, Non-specific Symptoms:
When the immune system is damaged, people begin to experience mild symptoms
Swollen lymph nodes
Fatigue
Weight loss
Frequent fevers and sweats
Frequent or persistent yeast infections
Persistent skin rashes
Shingles

11. Immune System Decline (continued)

12. Advanced HIV Disease / Clinical AIDS
The CDC has two different sets of criteria for diagnosing AIDS:
Set 1—An HIV infection, confirmed by testing, plus a CD4+ T-cell count
of less than 200 per cubic millimeter of blood
Set 2—An HIV infection, confirmed by testing, plus one of 26 clinical
conditions, primarily opportunistic infections that do not normally
affect healthy people

13. Opportunistic Infections
Infections that do not cause disease in people with healthy immune systems, for example:
Pneumocystis Carinii Pneumonia (PCP) (a kind of pneumonia)
Kaposi's Sarcoma (KS) (a kind of cancer)
HIV wasting syndrome (extreme weight loss)
Non-Hodgkin's lymphoma (a kind of cancer)
HIV encephalopathy (AIDS Dementia)
Candidiasis (Yeast Infection) of the trachea, bronchi, or lungs
Candidiasis (Yeast Infection) of the esophagus