Test Two: Module 7 HIV/AIDS

Question 1

How many people are estimated to be living with HIV world-wide?

Answer 1

35 million

Question 2

How many people were are newly infected each year?

Answer 2

2.3 million

Question 3

How many AIDS related deaths are estimated to occur each year?

Answer 3

1.6 million

Question 4

How many AIDS related deaths have their been since 1981?

Answer 4

36+ million

Question 5

What is the worst HIV/AIDS affected region in the world and how many people are estimated to be infected there?

Answer 5

Sub-saharan Africa; 25 million

Question 6

What subfamily does the HIV virus belong to and what is characteristic of these viruses?

Answer 6

Lentivirus; long incubation periods

Question 7

What are the two glycoproteins located on the HIV virus?

Answer 7

gp 120: outer membrane part

gp 41: trans-membrane part

Question 8

What is s retrovirus?

Answer 8

an RNA virus that is replicated in a host cell via the enzyme reverse transcriptase to produce DNA from its RNA genome

Question 9

What steps are involved in HIV entering the cell?

Answer 9

1) Primary binding
2) Secondary binding
3) Fusion of host and HIV
4) Insertion of HIV genome into host genome

Question 10

What are the steps in the primary binding of HIV?

Answer 10

HIV binds specifically to helper T-cells and monocytes that express CD4 surface protein. Primary binding occurs between gp 120 (of the virus) and CD4 surface proteins of the T cells or monocytes.

Question 11

What are the steps in secondary binding of HIV?

Answer 11

Primary binding induces secondary binding of gp 41 to either CCR5 (T-cells) or CXCR4 ( monocytes).

Question 12

What are the steps involved in the fusion of host and HIV?

Answer 12

Primary + secondary trigger fusion of host and viral membrane. . The fusion is mediated mostly by secondary binding causing the fusion mechanism, but primary binding is necessary for secondary binding to occur. The fusion mechanism is triggered when the CCR5 or CXCR4 is activated by gp41 and lead to serious of events in the host to allow HIV to fuse

Question 13

What is involved in the insertion of HIV genome into the host genome?

Answer 13

single stranded RNA of the virus are used by reverse transcriptase to create viral double stranded DNA that is incorporated into the host cell’s genome by the integrase enzyme.

Question 14

What is the function of reverse transcriptase in HIV replication?

Answer 14

Transcribes or makes mirror image of single-stranded viral RNA genome into double-stranded DNA

Question 15

What is the function of retroviral integrase?

Answer 15

enables its viral DNA genetic material to be integrated into the nuclear DNA of the infected cell.

Question 16

What is the role of protease?

Answer 16

)cleaves/slices newly synthesized polyproteins at the appropriate place
)Creates the mature protein components of an infectious HIV particles or virions
- **Without effective HIV PR, HIV virions remain noninfectious

Question 17

What are the 10 stages of HIV replication and the enzymes and/or proteins involved in each?

Answer 17

Stage 1: Free virus
Stage 2: Entry
- HIV binds to CD4 and co-receptor (CCR5/CXCR4)
- Gp 120 to CCR5 and CXCR4= Attachment
- gp 41 unfolds
- HIV and cell membrane fuse
Stage 3: Penetration
- HIV enters T-cell and releases 2 RNA strands
Stage 4: Reverse transcription
- Reverse transcriptase copies HIV RNA to DNA
Stage 5: Integration
- Integrase enables (new) HIV DNA to integrate into the nuclear DNA of the infected cell
Stage 6: Transcription
- Infected cell divides and protein chains produced
Stage 7: Assembly
-Viral proteins come together
Stage 8: budding
- Immature virion pushes out cell membrane
- Protease starts processing proteins
Stage 9: Breakaway
- Immature virus breaks free of infected cell
Stage 10: Maturation
- Protease cuts protein chains
- Individual proteins combine

Question 18

What is the incubation period for HIV?

Answer 18

Varies from months to years; Average length 7 years+, continues to increase as medicines get better at treating HIV

Question 19

What is the progression of HIV to AIDS?

Answer 19

1) Acute infection- within 2-4 weeks an acute illness
2) Clinical latency- asymptomatic HIV infection or chronic HIV infection “HIV positive” up to 8 years or longer
3) Constitutional symptoms- fever diarrhea, night sweats (AIDS related complex)
4) AIDS-CD4 cells fall below 200 cells per cubic millimeter of blood

Question 20

What happens to CD4 cells during the initial infection (12 weeks)?

Answer 20

Initially fall then increase as immune system responds

Question 21

What happens to CD4 cells during the latency period?

Answer 21

Initially rise due to immune system response then fall as it becomes overwhelmed

Question 22

What is the critical level for CD4 cells for opportunistic diseases?

Answer 22

Below 200 cells/mm3

Question 23

What are some of the first identified opportunistic diseases?

Answer 23

Kaposi’s sarcoma, pneumocystis carinii pneumonia

Question 24

When was HIV-1 first identified?

Answer 24

1981

Question 25

When was HIV-2 first identified?

Answer 25

1986, West Africa

Question 26

What is the differences between HIV-1 and HIV-2?

Answer 26

HIV-2 milder less virulent, less infectious early. Shorter duration. Associated with West Africa

Question 27

What is thought to be the origin of HIV-1 and HIV-2?

Answer 27

Pan troglodyte troglodyte chimpanzee SIV-> HIV-1

Sooty mangabey monkey SIV-> HIV-2

Question 28

What are some probable sources of SIV to humans?

Answer 28

Cultural practices (monkey blood injection), hunting of monkeys, polio vaccine testing, contaminated needles