HIV and AIDS

Question 1

HIV and AIDS

Answer 1

• chronic, progressive retroviral infection (prognosis gets better, but most ppl w HIV will develop AIDS, takes ~10 yrs)
• HIV leads to immunodeficiency
• complx of HIv results in AIDS
• retrovirus targets immune system (Th cells destroy defenses)
• no cure

Question 2

how does HIV lead to immunodeficiency?

Answer 2

virus incorporates itself into host cell to replicate (happens to target immune cells = ID)

Question 3

discuss how the retrovirus targets the immune system

Answer 3

• usually DNA transcribes into RNA and that forms proteins, but here the viruses take RNA and put it into DNA of the host
• this results in profound immunosuppression -> develop CA and infections very readily

Question 4

etiology

Answer 4

• HIV-1 and HIV-2 (strains of virus)

- 3 stages: primary infection, latency, overt AIDS (8-12 yrs)

Question 5

transmission

Answer 5

• sexual (semen can contain virus)
• contaminated blood, blood products, organs
• placenta, delivery (severed bv and baby is in contact
• lactation (through breast milk)
• needle stick injury (0.3% risk if precautions taken)

Question 6

how do you determine the degree of risk with a needle stick injury?

Answer 6

viral load, depth, and site of injury

Question 7

primary infection

Answer 7

• wks to months
• window period and seroconversion
• increased viral load (# of viral particles)
• decreased CD4 count

Question 8

window period

Answer 8

• time it takes for Abs to form

- dependent on microbe, individual, and dx test

Question 9

seroconversion

Answer 9

formation of Abs

Question 10

CD4

Answer 10

• cluster of differentiation 4
• surface protein on T helper cells, macrophages, and some epithelial cells
• CD4 count is an indirect measure of the # of T cells
• can’t be used for dx in primary stage
• CD4 and viral load are inversely proportionate

Question 11

latency

Answer 11

• could be asympt for yrs
• lymphadenopathy
• recurrent resp infections

Question 12

why do you have recurrent resp infections in the latency stage?

Answer 12

bc its through this system that most microbes and viruses enter via inhalation, but are usually fought off by a functioning immune system

Question 13

overt AIDS

Answer 13

• typically 60-70% of cases in 10 yrs (typical progressors)
• ~5yrs = rapid progressors
• ~15 yrs = slow progressors
• long term non-progressors (2-5%) -> don’t develop AIDS

Question 14

patho

Answer 14

• targets T helper cells (CD4)
• targets macrophages and B cells (Ab formation inhibited)
• destroys immune system -> decreased immunity and defenses -> many new systemic infections and via latent pathogens

Question 15

what happens when the virus targets T helper cells (CD4)?

Answer 15

responsible for cell-mediated response, if these cells are damaged then cytokines aren’t generated for immune cells to communicate with each other and the immune system is compromised

Question 16

diagnosis

Answer 16

• presentation and labs
• ELISA
• western blot assay
• PCR
• CD4 counts and viral loads (viral load not recommended for screening or dx)
• newer blood and saliva tests (P24 antigen)

Question 17

ELISA

Answer 17

• serology, Ab test
• Enzyme Linked Immunosorbant Assay
• body’s prod of Abs measured against entire virus using an enzymatic method
• if it’s positive, you confirm using a western blot

Question 18

western blot assay

Answer 18

• Abs prod to a specific part of the HIV virus

- more specific test

Question 19

PCR

Answer 19

• polymerase chain reaction
• amplifies genetic material and measures the viral particle itself
• not a routine test, but a research test

Question 20

P24 antigen

Answer 20

protein found in viral core and makes its appearance early (between infection and seroconversion, when Abs are detectable)

Question 21

manifestations

Answer 21

• many, systemic
• opportunistic infections that impact the resp tract, GI, nervous system
• opportunistic CA (Kaposi’s sarcoma, cervical CA, non-Hodgkin’s lymphoma)

Question 22

how do opportunistic infections impact the resp tract?

Answer 22

defense compromised so recurrent infection can not be prevented
ex.)TB and pneumonia

Question 23

how is the GI system impacted?

Answer 23

infections from normal flora and ingested microbes

ex.) diarrhea

Question 24

how is the nervous system impacted?

Answer 24

dementia, encephalopathy (impairment of CNS fx d/t various infections and the presence of the virus)

Question 25

opportunistic CA

Answer 25

malignant cells in the early stage are controlled by the immune system

Question 26

Kaposi’s sarcoma

Answer 26

mesenchyme origin (non-epithelial) -> arises in endothelial cells (lining bv), forms malignant lesions (appear in skin, mucosa of mouth, lymph nodes)

Question 27

why might you be at risk for cervical CA?

Answer 27

d/t HPV infection

Question 28

treatment

Answer 28

• no cure

- HAART

Question 29

HAART

Answer 29

• Highly Active Anti-Retroviral Therapy
• therapy targets reverse transcription used by the virus
• at least 3 antivirals are used -> each target a different step

Question 30

what are examples of antivirals that can be used in HAART?

Answer 30

1. reverse transcriptase inhibitors
2. protease inhibitors
3. entry inhibitors
4. integrase inhibitors

Question 31

entry inhibitors

Answer 31

inhibit entry into host cell, if the virus cannot get into the cell it can’t damage it

Question 32

integrase inhibitors

Answer 32

enzyme inhibited -> prevents the viral particle from integrating its RNA into the host’s DNA

Question 33

reverse transcriptase inhibitors

Answer 33

inhibit viral RNA replicating DNA and the multiplication of the virus

Question 34

protease inhibitors

Answer 34

inhibits the enzyme that breaks down proteins -> protease breaks up polypeptides in host cells