Acquired ImmunoDeficiency Acquired ImmunoDeficiency SyndromeSyndrome

- : عمر بشار عمار الطالبين اعدادرزوقي

Acquired immunodeficiency Acquired immunodeficiency syndrome:syndrome:

is an infectious secondary form of is an infectious secondary form of immunodeficiency caused by the immunodeficiency caused by the

retrovirus HIV-1, resulting in a defect in retrovirus HIV-1, resulting in a defect in cell-mediated immune response cell-mediated immune response

(therefore, leads to immune suppression) (therefore, leads to immune suppression) that is manifested by increased that is manifested by increased

opportunistic infections and to certain opportunistic infections and to certain rare cancersrare cancers

HIVHIV: A retrovirus that causes AIDS by : A retrovirus that causes AIDS by infecting helper T cells of the immune infecting helper T cells of the immune

system. The most common type, HIV-1, is system. The most common type, HIV-1, is distributed worldwide, while HIV-2 is distributed worldwide, while HIV-2 is

primarily confined to West Africaprimarily confined to West Africa . .

• HIV virus can be classified into 2 groups HIV virus can be classified into 2 groups on the basis of their ability to infect on the basis of their ability to infect macrophages an T-helper cells into:macrophages an T-helper cells into:

• 1. 1. M-tropicM-tropic which can infect both which can infect both macrophages and freshly isolated macrophages and freshly isolated peripheral T-cell.peripheral T-cell.

• 2. 2. T-tropicT-tropic which can infect only activated which can infect only activated T-cell.T-cell.

Structure of the Human Structure of the Human Immunodeficiency VirusImmunodeficiency Virus

Receptors and co-Receptors and co-receptors on the cell receptors on the cell

surface of the target cell surface of the target cell infected by HIVinfected by HIV

Routes of transmissionRoutes of transmission::

• HIV is transmitted primarily via HIV is transmitted primarily via sexual intercourse, contaminated sexual intercourse, contaminated blood transfusions and hypodermic blood transfusions and hypodermic needles, and from mother to child needles, and from mother to child during pregnancy (vertical during pregnancy (vertical transmission), delivery, or transmission), delivery, or breastfeeding breastfeeding

• Pathogenesis:Pathogenesis:• The main targets for HIV virus :The main targets for HIV virus :

• 1.immune system 1.immune system “immunopathogenesis”“immunopathogenesis”

• 2.C.N.S2.C.N.S

1. immunopathogenesis :1. immunopathogenesis :

the HIV infect mainly cells the HIV infect mainly cells which have CD4 receptor on which have CD4 receptor on their surface, which are:their surface, which are:

1. T-helper cells1. T-helper cells

2. Macrophages2. Macrophages

3. Dendritic cells3. Dendritic cells

4. Microglial cells4. Microglial cells

5. other cells5. other cells

Immunopathogenesis of Immunopathogenesis of HIV disease (continued)HIV disease (continued)

• the main event that occur during the the main event that occur during the infection is the destruction of CD4+ cells infection is the destruction of CD4+ cells by HIV.by HIV.

• since the CD4+ cells are very crucial to the since the CD4+ cells are very crucial to the immune system ,itimmune system ,it’’s destruction leads to s destruction leads to immune suppressionimmune suppression

• Due to immune suppression , opportunistic Due to immune suppression , opportunistic infections occur and neoplasms develop infections occur and neoplasms develop

• The mechanism of CD+4 destruction or The mechanism of CD+4 destruction or loss:loss:

• A. Death of infected cell (cytopathic A. Death of infected cell (cytopathic effect of the virus)effect of the virus)

• B. Activation-induced cell death B. Activation-induced cell death (apoptosis)(apoptosis)

• C. Killing of the infected cells by virus C. Killing of the infected cells by virus specific cytotoxic T-cellspecific cytotoxic T-cell

• Pathogenesis of C.N.S. involvement:Pathogenesis of C.N.S. involvement:• Nervous system is a major target of HIV Nervous system is a major target of HIV

infection either directly or indirectly.infection either directly or indirectly.

• Macrophages and microglialMacrophages and microglial cells are the cells are the predominant cell type infected with HIV predominant cell type infected with HIV

• Infected macrophages can act as HIV Infected macrophages can act as HIV reservoirs and as vehicles for viral reservoirs and as vehicles for viral transport especially to C.N.S.transport especially to C.N.S.

•C.N.S. injury can occur C.N.S. injury can occur directly directly by the infection of the by the infection of the virus itself (virus itself (the mechanism is the mechanism is obscure because the virus obscure because the virus doesndoesn’’t attack the neuronst attack the neurons) or ) or indirectlyindirectly by the viral by the viral products & factors produced products & factors produced by macrohages /microglial by macrohages /microglial cells e.g. cells e.g. IL1,TNF, &IL6IL1,TNF, &IL6

Life cycle of Life cycle of HIVHIV

Life cycle of HIVLife cycle of HIV• Initially, HIV-1 infects T cells Initially, HIV-1 infects T cells

and macrophages directly or is and macrophages directly or is carried to these cells by carried to these cells by Langerhans cells. Viral Langerhans cells. Viral replication in the regionalreplication in the regional

• lymph nodes leads to viremia lymph nodes leads to viremia and widespread seeding of and widespread seeding of lymphoid tissue. The viremia is lymphoid tissue. The viremia is controlled by the host immune controlled by the host immune response and the patient then response and the patient then enters a phase of clinical enters a phase of clinical latencylatency. .

• During this phase, viral replication During this phase, viral replication in both T cells and macrophages in both T cells and macrophages continues unabatedcontinues unabated

• There continues a gradualThere continues a gradual destruction of CD4+ cells by destruction of CD4+ cells by productive infection Ultimately, productive infection Ultimately, CD4+ cell numbers decline, and CD4+ cell numbers decline, and the patient develops clinical the patient develops clinical symptoms of full-blown AIDS.symptoms of full-blown AIDS.

• Syndromes associated with AIDSSyndromes associated with AIDS

A . Opportunistic infectionA . Opportunistic infection

B . NeoplasmsB . Neoplasms

A . Opportunistic infection:A . Opportunistic infection:• CandidiasisCandidiasis• ToxoplasmosisToxoplasmosis• Herpes simplex virusHerpes simplex virus• Pneumocystis jiruvechiiPneumocystis jiruvechii (formerly P.carinii) (formerly P.carinii)• CytomegalovirusCytomegalovirus• Mycobacteria Mycobacteria • and othersand others

B.NeoplasmsB.Neoplasms• Kaposi sarcomaKaposi sarcoma• B-cell non-Hodgkin lymphomasB-cell non-Hodgkin lymphomas• Invasive cancer of uterine cervixInvasive cancer of uterine cervix• Primary lymphoma of the brainPrimary lymphoma of the brain• othersothers

Oral thrush

)candidiasis)

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