Pathogenesis of AIDS Flashcards
How are individuals staged after diagnosis of HIV?
Stage 0: early infection, recognized by HIV-test within 180 days of first HIVG+ test (acute retroviral syndrome)
Stage 1 - 3 based on age-specific CD4 t-cell count
Which stage is considered to be AIDS?
stage 3
Which two stages have no AIDS defining conditions?
Stage 1 and 2
When can staging be bi-directional?
When there is no AIDS-defining condition present
What are the phases of HIV infection?
1 Acute retroviral syndrome (weeks)
- Chronic HIV (years -decades)
- Aids (months to years)
In chronic HIV in which tissues are viruses trapped?
lymphoid tissue
During asymptomatic phases the HIV patient is not infectious. (T/F)
False. highly infectious
What are the most common presentation?
constitutional
Lymphatics
While in clinical latency, how does the viral load change in the blood?
load increase
What is AIDS dementia?
when the virus crosses the blood-brain barrier
What happens due to the loss of CD4 cells during chronic HIV?
loss of control of nonlymphoid cells, loss of DTH response»»control of bacteria, fungi and virus
What happens to the macrophages and dendritic cells during chronic HIV?
-macrophages carry HIV into CNS
-excess secretion of cytokines in lymph noes
Decreased:
- antigen presentation
-MHCII expression
chemotaxis
phagocytica ability
cytotoxic ability
What happens during AIDS dementia complex (ADC)?
memory loss impaired cognition impaired motor function behavioral changes apathy depression
When does ADC (AIDS dementia complex) typically occur?
as CD4 count falls to < 200 cells/microliter
How does HIV evade the immune system?
- antigenic drift of gp120 (evades antibody detection)
- heavy glycosylation of gp120 (evasion of antibody detection)
- infection of lymphocytes and macrophages (inactivation of ley element of immune defense)
- inactivation of CD4 helper cells (loss of activator of the immune system and delayed-type hypersensitivity)
What is a rapid progressor?
AIDS in 2-3 years (probably CCR5)
What is a typical progressor?
AIDS in 10 years
What is a long-term nonprogressor
low HIV levels; normal CD4 cell; >10 years after HIV positive
HIV-2 (CXCR4)- less virulent
What are the implications of R5 vs. X4 infection?
R5-(M-tropic) macrophages and DC are persistently infected
CD4 cells lyse - deplete Tcells in GALT
X4 - (T-tropic) occurs late and there is a change in receptor preference to CSCR4
- mutation in env gene for gp120 shifts this tropism
- development of AIDS
Do some people possess natural immunity? why?
1 -CCR5-delta32 mutation
CXCR4 mutation
2 -HLA B57 - produce larger number of killer T Cells
3 - Some acquire specific immune defenses
4 - frequent sexual exposure to HIV
