HIV 101 Review
Evaluation Center for HIV and Oral Health
Boston University School of Public Health
Health & Disability Working Group
What is the Immune System?
• The immune system is the body’s natural guardian
against disease.
• It consists of specialized cells (including CD4 cells) that
defend the body against attacks by ‘foreign’ invaders
such as bacteria, viruses, fungi, parasites, and cancer.
• The immune system is continuously working to protect
us against these foreign invaders.
• Without an immune system, we would very quickly
succumb to disease
Where is the Immune System?
DEFINITIONS
• CD4 T-Cells: Important cells in the human body for
mounting the body’s immune defense against
infection. These “helper” cells not only fight
infection, but recruit other immune cells to the site
of infection to help kill infection-causing bacteria
and viruses. The HIV uses the CD4 T-cells to make
more HIV. By doing this, HIV destroys the CD4
cell. Without CD4 T-cells, the body is not able to
defend itself against bacterial and viral infections.
HIV
• Virus is in the bloodstream but also hides
in other cells (e.g. lymph nodes)
– Drugs don’t reach these sequestered cells*
– That’s why there is no cure
• Virus destroys CD4 cells which lead to:
– Immune suppression
– Opportunistic infections and AIDS
*HIV hides in cells in certain organs which are “protected” by the body: lymph nodes, the
brain, reproductive organs. Not enough meds can get to those cells.
DEFINITIONS
• DNA: The chemical make-up of living things.
DNA contains 2 copies of information.
• RNA: the chemical make up of living things.
RNA contains only 1 copy of information and
needs another copy to replicate.
• HIV: A virus that can only survive in host cells.
It carries with it RNA, but must make DNA to
replicate.
DNA versus RNA
DEFINITIONS
• Viral load test shows the amount of HIV RNA in
your blood and tells you how active the virus is
in your body. Higher numbers mean you have
more virus in your body.
• Opportunistic infections are illnesses caused
by different organisms, some of which do not
usually cause disease in people with a normal
immune system. Opportunistic infections of the
lungs, brain, eyes, and other organs can
develop in people with HIV infection.
Viral load
• One of the most important tests you will
take about every 3 months
• Often considered the critical marker in the
management of HIV and AIDS
• Measures the amount of HIV in your blood
CD4 cell count
• Measures the number of CD4 cells (also
called T-helper cells) in your body
– Tells you the health of your immune system
– The more CD4 cells you have, the stronger
your immune system
Fewer
CD4 cells
may lead to
Increased
infections
What are some opportunistic
infections (OIs)?
• Candidiasis (Thrush) is a fungal infection of the mouth,
throat, or vagina. CD4 cell range: can occur even with fairly
high CD4 cells.
• Cytomegalovirus (CMV) is a viral infection that causes eye
disease that can lead to blindness.CD4 cell range: under 50.
• Herpes simplex viruses can cause oral herpes (cold sores)
or genital herpes. These are fairly common infections, but if you
have HIV, the outbreaks can be much more frequent and more
severe. They can occur at any CD4 cell count.
• Malaria is common in the developing world. It is more
common and more severe in people with HIV infection.
More Opportunistic Infections
• Mycobacterium avium complex (MAC or MAI) is a bacterial
infection that can cause recurring fevers, general sick feelings,
problems with digestion, and serious weight loss. CD4 cell
range: under 75.
• Pneumocystis pneumonia (PCP) is a fungal infection that
can cause a fatal pneumonia. CD4 cell range: under 200.
Unfortunately this is still a fairly common OI in people who have
not been tested or treated for HIV.
• Toxoplasmosis (Toxo) is a protozoal infection of the brain. Tcell range: under 100.
• Tuberculosis (TB) is a bacterial infection that attacks the
lungs, and can cause meningitis. CD4 cell range: Everyone with
HIV who tests positive for exposure to TB should be treated.
What does HAART stand for?
• HAART: Highly Active Antiretroviral Therapy
• A combination of HIV medicines from different
groups that are taken together to keep HIV
levels down
Principles of HAART
• HIV virus has 1 goal: replication
• Triple-drug therapy
– “Attack” virus in several different ways
– Slow down viral replication
– Allow immune system to ‘recover’
How do HIV medicines work?
• HIV medicines slow down the reproduction of
the virus at various stages
• Each HIV medicine group fights HIV in different
ways
– Main difference: the stage of HIV
reproduction that is targeted
Young boy from Indiana…
And his legacy…
• Before Ryan White, HIV/AIDS was
considered a “homosexual problem” and
largely ignored by policymakers
• Four months after White's death, Congress
enacted The Ryan White Comprehensive
AIDS Resources Emergency (CARE) Act
• Largest federally funded program for people
living with HIV/AIDS