Immunology of AIDS

Question 1

What is unique about long term survivors?

Answer 1

some are homozygous for a mutation in the CCR5 receptor

Question 2

What happens first when someone is infected with HIV?

Answer 2

high blood virus levels develop and peak around 6 weeks

Question 3

____ are able to suppress viral replication but not eliminate the virus DNA from their nuclei.

Answer 3

Tfh cells

Question 4

Once they get symptoms of _____ or _____, or their Th (CD4+) cells fall below 200/μL of blood, it’s AIDS.

Answer 4

opportunistic infections; Kaposi’s sarcoma

Question 5

How does HIV bind to Th cells?

Answer 5

using its gp120 envelope glycoprotein to CD4

Question 6

People are ‘______’ if they have antibody to HIV.

Answer 6

seropositive

Question 7

Once they get symptoms of opportunistic infections or Kaposi’s sarcoma, or their Th (CD4+) cells fall below ___ of blood, it’s AIDS.

Answer 7

200/μL

Question 7

During the _____, the major site of HIV persistence is memory Tfh cells in the lymph nodes.

Answer 7

long seropositive period

Question 8

What is the normal CD4/CD8 ratio?

Answer 8

1.5:3

Question 9

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.

Answer 9

nucleosides (NRTI); non-nucleoside (NNRTI)

Question 10

What is ART?

Answer 10

standard antiretroviral therapy that combines two NRTIs and a third drug from a different class, usually an NNRTI

Question 11

Why does HIV want to form a syncytium?

Answer 11

to spread without going extracellular

Question 11

During the long seropositive period, the major site of HIV persistence is _____ cells in the lymph nodes.

Answer 11

memory Tfh

Question 12

These are some long term survivors that became infected with HIV but did not progress to AIDS; some have HLA-B57.

Answer 12

elite controllers

Question 13

Why do CD4 cell counts eventually fall?

Answer 13

the immune system can no longer keep up

Question 15

These are viruses that cause slow disease progressions but are ultimately fatal.

Answer 15

lentiviruses

Question 16

People are ‘seropositive’ if they have _____.

Answer 16

antibody to HIV

Question 16

HIV-1 is the most _____ pathogenic virus we have encountered.

Answer 16

antigenically variable

Question 17

What are elite controllers?

Answer 17

some long term survivors that became infected with HIV but did not progress to AIDS; some have HLA-B57

Question 18

What is a lentivirus?.

Answer 18

viruses that cause slow disease progressions but are ultimately fatal

Question 18

____ is the leading cause of death in people infected with HIV.

Answer 18

TB

Question 19

Tfh cells are able to suppress viral replication but not _____.

Answer 19

eliminate the virus DNA from their nuclei

Question 20

_____ is a tumor of the endothelial cells lining lymphatics.

Answer 20

Kaposi sarcoma

Question 21

What is CCR5?

Answer 21

an HIV coreceptor

Question 21

What is important about the HLA-B57 allele?

Answer 21

pts with it make effective CTL to HIV peptides presented in HLA-B57

Question 23

What happens to HIV infected T cells?

Answer 23

1. die rapidly OR 2. become persistent viral producers OR 3. enter latency

Question 25

HIV binds to cells via ____ on _____ called _____.

Answer 25

lectin; dendritic cells; DC-SIGN

Question 27

What is the mean incubation period from HIV to AIDS?

Answer 27

9.5 years w/o treatment

Question 28

HIV virus type?

Answer 28

a nontransforming retrovirus,

Question 29

What happens after HIV uses its gp120 to bind to Th cells?

Answer 29

gp120 undergoes a conformational change, allowing it to bind to the CCR5 co-receptor

Question 31

Antibody to HIV peaks around ____, and then ____.

Answer 31

9 weeks; virus levels fall to almost zero

Question 32

Why does ELISA for HIV have to be followed up with a Western blot?

Answer 32

ELISA has a false-positive rate

Question 33

What does gp120/gp41 do?

Answer 33

when inserted in the plasma membrane, it allows fusion of the infected cell to nearby cells, forming a syncytium