HIV/AIDS Flashcards
(44 cards)
Classification based on HIV
infection stages
Stage O: negative HIV test within 6 months of the first HIV infection diagnosis,remain O until 6 months after diagnosis
Stage 3: Advanced HIV or AIDS,
if one or more opportunistic illness has been diagnosed
Stage U: Unknown, if none of the criteria apply
AIDS-defining opportunistic
illnesses in HIV infection
Characteristics of the etiologic
agent HIV and its antigenic determinants crucial for infection
Replication cycle of HIV
Note:
Binding: gp120 ->CD4 molecule
Co-receptors for HIV-1 : CCR5 and CXCR4
Fusion: gp41
Integrase - enzyme that integrates viral DNA into the host’s genome
Molecular heterogeneity of
HIV-1 and the four groups of
HIV-1
Predominant CRF in southeast
asia
CRFO1_AE
Mechanisms of viral
transmission in different
settings (sexual, transfusion,
occupational, maternal-fetal,
etc.)
HIV is transmitted primarily by sexual contact (both heterosexual and
male to male); by blood and blood products; and by infected mothers to infants intrapartum, perinatally, or via breast milk
Epidemiology of HIV infection
and AIDS in Asia and SE Asia
General hallmark of HIV disease
is a profound immunodeficiency resulting primarily from a progressive quantitative and qualitative deficiency of a subset of T lymphocytes referred to as helper T cells occurring in a setting of polyclonal immune activation
Mechanisms of CD4+ T cell
depletion or dysfunction
Course of Primary HIV infection, initial viremia, and viral dissemination
Role of co-receptors in HIV
pathogenesis
Mechanisms of establishing
chronic and persistent infection
Immune activation and inflammation in
HIV pathogenesis
VIral escape through mutation
Overwhelming immune activation d/t persistent viral replication ->”immune exhausion”
Downregulation of HLA class I molecules -> lack of CD8+ cells to recognize and kill infected target cells
Three mechanism of Immune Evasion
- Hypervariability in the primary sequence of the envelope
- Extensive glycosylation of the envelope
- Conformational masking of neutralizing epitopes
Reservoirs of HIV-infected cells
Lymphoid tissue
Peripheral blood
CNS (cells of monocyte/macrophage lineage)
*Resting CD4+ T cells- serves as one component of the persistent reservoir of virus
Features of advanced HIV
disease
HIV Stage 3 (AIDS)
- HIV-infected individuals >5 years with CD4+ T cell counts <200
- depletion of CD4+ T cells continues to be progressive and unrelenting in this phase
-may develop opportunistic infection abruptly without any prior symptoms
HIV infected individuals treated with ART
Longterm survivors
Infected with HIV for a long period (>10 years) their CD4+ T cells counts were in the normal range, their plasma viremia remained relatively low, and they remained clinically stable over years without receiving ART
Longterm nonprogressors
Individuals with extremely low levels of viremia that is often undetectable by standard assays and normal CD4+ T cell counts
Elite controller
Diagnostic approach in HIV
infection
Diagnosis depends on the demonstration of antibodies to HIV and/or the direct detection of HIV or one of its components
(Ab appears 3-12 weeks following infection)
-CDC recommendations indicate that a positive 4th generation assay confirmed by a second HIV-1 and HIV-2 specific immunoassay or a plasma HIV RNA level is adequate for diagnosis
False-positive in HIV infection
Antibodies to class II antigens (following pregnancy, blood transfusion, or transplant)
Autoantibodies
Hepatic diseases
Recent influenza vaccination
Acute viral infections
Administration of HIV vaccine
Guidelines on serologic testing
in HIV-1 diagnosis
Laboratory monitoring in HIV
infection
- CD4 count
- best indicator of and correlates with the level of immunologic competence
-measured at the time of diagnosis ->every 3-6 mo x 2 years of ART - HIV RNA determination
-used to monitor ART effectiveness
-measure before initiation of ART
-monitoring of viral load is done at 4-8 weeks until viral suppression is achieved then dec to 3-4 mo or 6 mo if stable for 2 years or more - HIV resistance testing
-should be performed if with failing treatment
