Immunology of AIDS Flashcards
What is unique about long term survivors?
some are homozygous for a mutation in the CCR5 receptor
What happens first when someone is infected with HIV?
high blood virus levels develop and peak around 6 weeks
____ are able to suppress viral replication but not eliminate the virus DNA from their nuclei.
Tfh cells
Once they get symptoms of _____ or _____, or their Th (CD4+) cells fall below 200/μL of blood, it’s AIDS.
opportunistic infections; Kaposi’s sarcoma
How does HIV bind to Th cells?
using its gp120 envelope glycoprotein to CD4
People are ‘______’ if they have antibody to HIV.
seropositive
Once they get symptoms of opportunistic infections or Kaposi’s sarcoma, or their Th (CD4+) cells fall below ___ of blood, it’s AIDS.
200/μL
During the _____, the major site of HIV persistence is memory Tfh cells in the lymph nodes.
long seropositive period
What is the normal CD4/CD8 ratio?
1.5:3
There are two classes of RT inhibitors: ____, which are competitive inhibitors and chain-terminators; and _____ inhibitors, which bind a hydrophobic pocket on the enzyme that changes the conformationof the catalytic site.
nucleosides (NRTI); non-nucleoside (NNRTI)
What is ART?
standard antiretroviral therapy that combines two NRTIs and a third drug from a different class, usually an NNRTI
Why does HIV want to form a syncytium?
to spread without going extracellular
During the long seropositive period, the major site of HIV persistence is _____ cells in the lymph nodes.
memory Tfh
These are some long term survivors that became infected with HIV but did not progress to AIDS; some have HLA-B57.
elite controllers
Why do CD4 cell counts eventually fall?
the immune system can no longer keep up
These are viruses that cause slow disease progressions but are ultimately fatal.
lentiviruses
People are ‘seropositive’ if they have _____.
antibody to HIV
HIV-1 is the most _____ pathogenic virus we have encountered.
antigenically variable
What are elite controllers?
some long term survivors that became infected with HIV but did not progress to AIDS; some have HLA-B57
What is a lentivirus?.
viruses that cause slow disease progressions but are ultimately fatal
____ is the leading cause of death in people infected with HIV.
TB
Tfh cells are able to suppress viral replication but not _____.
eliminate the virus DNA from their nuclei
_____ is a tumor of the endothelial cells lining lymphatics.
Kaposi sarcoma
What is CCR5?
an HIV coreceptor
What is important about the HLA-B57 allele?
pts with it make effective CTL to HIV peptides presented in HLA-B57
What happens to HIV infected T cells?
- die rapidly OR 2. become persistent viral producers OR 3. enter latency
HIV binds to cells via ____ on _____ called _____.
lectin; dendritic cells; DC-SIGN
What is the mean incubation period from HIV to AIDS?
9.5 years w/o treatment
HIV virus type?
a nontransforming retrovirus,
What happens after HIV uses its gp120 to bind to Th cells?
gp120 undergoes a conformational change, allowing it to bind to the CCR5 co-receptor
Antibody to HIV peaks around ____, and then ____.
9 weeks; virus levels fall to almost zero
Why does ELISA for HIV have to be followed up with a Western blot?
ELISA has a false-positive rate
What does gp120/gp41 do?
when inserted in the plasma membrane, it allows fusion of the infected cell to nearby cells, forming a syncytium
