Test Two: Module 7 HIV/AIDS Flashcards
(28 cards)
How many people are estimated to be living with HIV world-wide?
35 million
How many people were are newly infected each year?
2.3 million
How many AIDS related deaths are estimated to occur each year?
1.6 million
How many AIDS related deaths have their been since 1981?
36+ million
What is the worst HIV/AIDS affected region in the world and how many people are estimated to be infected there?
Sub-saharan Africa; 25 million
What subfamily does the HIV virus belong to and what is characteristic of these viruses?
Lentivirus; long incubation periods
What are the two glycoproteins located on the HIV virus?
gp 120: outer membrane part
gp 41: trans-membrane part
What is s retrovirus?
an RNA virus that is replicated in a host cell via the enzyme reverse transcriptase to produce DNA from its RNA genome
What steps are involved in HIV entering the cell?
1) Primary binding
2) Secondary binding
3) Fusion of host and HIV
4) Insertion of HIV genome into host genome
What are the steps in the primary binding of HIV?
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.
What are the steps in secondary binding of HIV?
Primary binding induces secondary binding of gp 41 to either CCR5 (T-cells) or CXCR4 ( monocytes).
What are the steps involved in the fusion of host and HIV?
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
What is involved in the insertion of HIV genome into the host genome?
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.
What is the function of reverse transcriptase in HIV replication?
Transcribes or makes mirror image of single-stranded viral RNA genome into double-stranded DNA
What is the function of retroviral integrase?
enables its viral DNA genetic material to be integrated into the nuclear DNA of the infected cell.
What is the role of protease?
)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
What are the 10 stages of HIV replication and the enzymes and/or proteins involved in each?
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
What is the incubation period for HIV?
Varies from months to years; Average length 7 years+, continues to increase as medicines get better at treating HIV
What is the progression of HIV to AIDS?
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
What happens to CD4 cells during the initial infection (12 weeks)?
Initially fall then increase as immune system responds
What happens to CD4 cells during the latency period?
Initially rise due to immune system response then fall as it becomes overwhelmed
What is the critical level for CD4 cells for opportunistic diseases?
Below 200 cells/mm3
What are some of the first identified opportunistic diseases?
Kaposi’s sarcoma, pneumocystis carinii pneumonia
When was HIV-1 first identified?
1981
