Micro 6.

Question 1

What is HIV?

Answer 1

a zoonotic disease - introduced to humans by chimpanzees in central Africa

Question 2

What is treatment for HIV?

Answer 2

HAART - highly active antiretroviral therapy

Question 3

What is PEP?

Answer 3

post exposure prophylaxis - the use of antiretroviral drugs after a single high-risk event to stop HIV from making copies of itself and spreading through your body - must be used within 3 days

Question 4

Who has the highest risk of HIV in the US?

Answer 4

gay/bisexual African American Men - especially younger

Question 5

Upon exposure, who is most likely to become infected with HIV?

Answer 5

women

Question 6

What do HIV virions infect?

Answer 6

lymphoid cells that are embedded in the vaginal and rectal epithelium - tissue macrophages, dendritic cells, etc

Question 7

Where do visions migrate after initial infection?

Answer 7

to lymph nodes

Question 8

What are the main symptoms of acute HIV infection?

Answer 8

fever, weight loss, sores and thrush of mouth, myalgia, hepatomegaly, nausea, vomiting, rash, lymphadenopathy, headache, neuropathy, malaise

Question 9

Bacteriology HIV

Answer 9

ssRNA, (+) strand, slow to cause disease (lentivirus), two copies in each vision (diploid - for more variability)

Question 10

What receptors must be present on a cell in order to induce HIV attachment and fusion? (early in infection)

Answer 10

CD4 and CCR5 coreceptor

Question 11

Mutations in what change the coreceptor HIV binds to on CD4 cells? What is the advantage of this for the virus?

Answer 11

mutations in Env change binding to CXCR4 instead of CCR5 - this helps cells fuse together

Question 12

What is mRNA synthesis completed by?

Answer 12

host RNAPII

Question 13

What is replication phase I?

Answer 13

genomes are reverse-transcribed in the cytoplasm (by RT) and then integrate (IN) of HIV into host chromosome

Question 14

What is replication phase II?

Answer 14

mRNA by host RNAPII and genome synthesis - protease cleave for final step of maturation

Question 15

When can syncytia be formed?

Answer 15

after virion maturation - a multinucleate cell - multiple fusions of cells

Question 16

What is Env?

Answer 16

HIV - composed of TM (transmembrane, gp41) and SU (surface gp120 domains) and cleaved by host proteases - SU binds CD4 and chemokine receptors which causes conformation change in TM - TM inserts in target cell membrane and induces virus entry

Question 17

CCR5

Answer 17

for macrophages

Question 18

CXCR4

Answer 18

for T cells (mutations in Env in order to infect these cells)

Question 19

What is the primer in reverse transcription of HIV?

Answer 19

tRNA bound to ssRNA

Question 20

What is the primary obstacle to eradicating HIV from a person?

Answer 20

viral genome becomes part of the cell for the life of the cell creating a reservoir of latent virus

Question 21

What does discontinuation of HAART allow?

Answer 21

viral relapse from latent reservoir

Question 22

Do patients successfully treated with HAART after 10 years exhibit an appreciable decrease in the size of the latent reservoir?

Answer 22

NO

Question 23

Mature virion

Answer 23

infectious - HIV protease cleaves Gag into subunits resulting in capsid assuming its trapezoidal shape

Question 24

Immature virion

Answer 24

not infectious - formed when they bud from plasma membrane

Question 25

What is significant about the HIV protease?

Answer 25

essential because takes immature virion and makes it mature - target for antiretroviral drug therapy

Question 26

3 domains for Gag polyprotein

Answer 26

MA - binds cytoplasmic tail of TM+SU, CA structural, NC bind to the RNA genome

Question 27

Functions of Env

Answer 27

mediates HIV virion attachment and entry into T cells and macrophages; fuse infected T cells with unaffected T cells

Question 28

Which version of HIV is most virulent?

Answer 28

syncytium-inducing strains

Question 29

How does HIV infect macrophages and T helper cells/

Answer 29

through Env binding to CD4 receptor and CCR5 and CXCR4 co-receptors

Question 30

What are the stages of HIV disease?

Answer 30

1. exposure to virus (transmission) 2. primary HIV infection (acute phase) 3. seroconversion 4. clinical latent period 5. early symptomatic HIV infection 6. AIDS 7. advanced HIV infection (CD4 below 50)

Question 31

What are the main symptoms of AIDS?

Answer 31

encephalitis, meningitis, retinitis, pneumonia, TB, tumors, esophagitis, chronic diarrhea

Question 32

How does HIV escape immune control?

Answer 32

accumulation of virulence mutations

Question 33

How are CD8 cells affected by HIV?

Answer 33

as CD4 cells are depleted, less IL-2 is produced causing poor cytotoxic T cell functions

Question 34

How are B cells affected by HIV?

Answer 34

hyper-activation but lacking T cell help prevents mature Ig responses

Question 35

What is the main means of HIV transmission worldwide?

Answer 35

unprotected heterosexual sex

Question 36

What is the HIV structure?

Answer 36

enveloped, trapezoidal capsid, ssRNA genome

Question 37

What are the co-receptors used by the HIV virus for entry?

Answer 37

chemokine receptors

Question 38

Following entry, what are the next steps in the HIV lifecycle?

Answer 38

conversion to DNA, circularization, migration to the nucleus, integration into the chromosome