LECTURE OUTLINE #2: HIV and AIDS
I. INTRODUCTION
1. The HIV virus is the microbe
that causes the disease. HIV =
Human Immunodeficiency Virus
2. AIDS (Acquired Immune
Deficiency Syndrome) is a "condition" (i.e., a syndrome), not a
disease. (NOTE: When the CD4+ T-cell count
goes below 200 cells/mm3, the syndrome is
expressed.)
II. LIFE CYCLE OF THE
HIV RETROVIRUS
1. The HIV virus has a round, symmetrical
appearance (Figure #1).
2. Become familiar with the names and functions
of the different parts of the virus (Figure #2)
3. The HIV virus is a retrovirus, i.e., it
contains RNA that is converted into DNA in infected cells.
4. This is the reverse of the usual conversion
of DNA into RNA, and is called reverse
transcription.
(NOTE: Click on the following figure for a
description of reverse transcription. Figure #3)
5. Cells like T cells and macrophages have a transmembrane
receptor called CD4
on their surface.
6. The surface of an HIV virus has a glycoprotein called
gp120 that binds to
the CD4 on immune cells.
7. CD4 is also on a few regulatory T cells, monocytes, and B
cells, which can also be infected.
8. Following attachment to CD4, the virus enters
the immune cell and produces reverse transcriptase.
9 This enzyme allows the HIV virus to make many DNA replicas of
its viral RNA. (Figure #4)
10. The virus also
makes the enzyme integrase that integrates the viral DNA into the normal
DNA of the infected immune cell. Thus,
normal transcription
of the infected cell produces more viral RNA.
11. The replicating virus destroys the immune
cell (e.g., the T cell) and spreads to infect other cells.
12. As infection progresses, it weakens the immune system, and
the AIDS
syndrome sets in. (Fig. #5)
13. Eventually,
HIV/AIDS patients die from Kaposi's sarcoma,
which causes lesions of the mouth and skin, or from Pneumocystis
pneumonia, and excessive congestion of the lungs.
III. MORE ON THE PAST HISTORY AND PRESENT STATUS OF HIV/AIDS
NOTE: This
portion of the lecture is based primarily on a Wikipedia
website about AIDS
1. Discovery
of AIDS and the HIV virus by the CDC
on June 5, 1981.
2. Origin
of HIV has not been proven, but probably in the
3. Epidemiology of HIV has been studied extensively by the CDC, UNAIDS and WHO.
4. Treatment of HIV is now mainly by
‘cocktails’ of reverse transcriptase and protease inhibitors.
IV. OTHER HIV/AIDS-RELATED INFORMATION
1. A variety of
specific information is available. One
good source is GreenFacts.
2. For More
Information on HIV/AIDS, go to:
www.cdc.gov/hiv/pubs/facts.htm
www.aidsinfo.nih.gov/other/hivtr.pdf
.
http://news.yahoo.com/fc?tmpl=fc&cid=34&in=health&cat=aids___hiv