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Acquired ImmunoDeficiency Syndrome
‫ عمر رزوقي‬- ‫ عمار بشار‬:‫اعداد الطالبين‬
Acquired immunodeficiency syndrome:
is an infectious secondary form of
immunodeficiency caused by the retrovirus
HIV-1, resulting in a defect in cell-mediated
immune response (therefore, leads to immune
suppression) that is manifested by increased
opportunistic infections and to certain rare
HIV: A retrovirus that causes AIDS by infecting
helper T cells of the immune system. The most
common type, HIV-1, is distributed worldwide,
while HIV-2 is primarily confined to West
• HIV virus can be classified into 2 groups on the
basis of their ability to infect macrophages an Thelper cells into:
• 1. M-tropic which can infect both macrophages
and freshly isolated peripheral T-cell.
• 2. T-tropic which can infect only activated T-cell.
Structure of the Human Immunodeficiency
Receptors and co-receptors on
the cell surface of the target cell
infected by HIV
Routes of transmission:
• HIV is transmitted primarily via sexual
intercourse, contaminated blood
transfusions and hypodermic needles, and
from mother to child during pregnancy
(vertical transmission), delivery, or
• Pathogenesis:
• The main targets for HIV virus :
• 1.immune system “immunopathogenesis”
• 2.C.N.S
1. immunopathogenesis :
the HIV infect mainly cells which
have CD4 receptor on their
surface, which are:
1. T-helper cells
2. Macrophages
3. Dendritic cells
4. Microglial cells
5. other cells
Immunopathogenesis of HIV
disease (continued)
• the main event that occur during the infection
is the destruction of CD4+ cells by HIV.
• since the CD4+ cells are very crucial to the
immune system ,it’s destruction leads to
immune suppression
• Due to immune suppression , opportunistic
infections occur and neoplasms develop
• The mechanism of CD+4 destruction or loss:
• A. Death of infected cell (cytopathic effect of
the virus)
• B. Activation-induced cell death (apoptosis)
• C. Killing of the infected cells by virus specific
cytotoxic T-cell
• Pathogenesis of C.N.S. involvement:
• Nervous system is a major target of HIV
infection either directly or indirectly.
• Macrophages and microglial cells are the
predominant cell type infected with HIV
• Infected macrophages can act as HIV
reservoirs and as vehicles for viral transport
especially to C.N.S.
•C.N.S. injury can occur directly
by the infection of the virus itself
(the mechanism is obscure
because the virus doesn’t attack
the neurons) or indirectly by the
viral products & factors produced
by macrohages /microglial cells
e.g. IL1,TNF, &IL6
Life cycle of HIV
Life cycle of HIV
• Initially, HIV-1 infects T cells and
macrophages directly or is carried
to these cells by Langerhans cells.
Viral replication in the regional
• lymph nodes leads to viremia and
widespread seeding of lymphoid
tissue. The viremia is controlled
by the host immune response and
the patient then enters a phase of
clinical latency.
• During this phase, viral replication in
both T cells and macrophages
continues unabated
• There continues a gradual destruction
of CD4+ cells by productive infection
Ultimately, CD4+ cell numbers
decline, and the patient develops
clinical symptoms of full-blown
Syndromes associated with AIDS
A . Opportunistic infection
B . Neoplasms
A . Opportunistic infection:
Herpes simplex virus
Pneumocystis jiruvechii (formerly P.carinii)
and others
Kaposi sarcoma
B-cell non-Hodgkin lymphomas
Invasive cancer of uterine cervix
Primary lymphoma of the brain
Oral thrush
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