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29 Cards in this Set
- Front
- Back
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Are retroviruses enveloped or nonenveloped?
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Enveloped
- have single glycoprotein called "Enveloped" (Env) protruding from viral membrane |
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What are the 3 genes that all retroviruses have?
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1. gag - (group specific antigen). Forms capsid
2. pol - makes 3 enzymes made by retrovirues: protease, integrase, and reverse transcriptase. 3. env: makes envelope protein |
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Does Reverse Transcriptase (RT) have proof reading capability?
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No, thus retroviruses like HIV can mutate quickly.
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What does the enzyme integrase do for retroviruses?
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Integrates DNA into host's genome and allows retrovirus infections to persist FOR LIFE.
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Where does HIV integrate into human host chromosomes?
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HIV can integrate anywhere, but tends to integrate in active genes. This can potentially lead to activation of oncogene.
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What is the role of protease for HIV?
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Protease cleaves the polypeptide into many component parts, including RT, integrase, an viral core proteins.
Protease is an IMPORTANT DRUG TARGET |
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What 1 of 2 conditions does an HIV+ patient need to meet in order to have AIDS?
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Either:
1. CD4 counts fall below 200/mL 2. Have an AIDS defining illness |
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When was the virus responsible for AIDS discovered?
When was first reported case? |
Discovered: 1983
First reported case: June 1981 |
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In the US, how many people are HIV+?
Have AIDS? How many new cases / year? |
HIV+: 1.1 Million (20% unaware)
AIDS: 470,000 56,000 new cases / year |
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How many deaths / year are caused by AIDS?
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20,000
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How many total people worldwide have been infected with HIV?
How many deaths have resulted? How many new cases / year? |
>60 million have been infected
>20 million deaths >2.5 million new cases / year |
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How many people worldwide die / year from AIDS?
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>2 million deaths / year from AIDS
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What is the leading cause of death in Africa?
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HIV (highest rate in Botswana)
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Where did HIV-1 arise from?
HIV-2? |
- HIV-1 arose from chimp-human transmission
- HIV-2 arose from sooty mangabey-human transmission |
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What virus probably gave rise to HIV?
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Simian Immunodeficiency Virus (SIV)
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What is zoonosis?
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A disease or infection naturally transmitted between vertebrate animals (the reservoir) and humans.
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What 2 characteristics of HIV make treatment with only 1 drug likely to fail?
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1. Its high replication rate (10^10) new virus particles made per day
2. High Error Rate: Reverse transcriptase makes error 1 /10,000 bases. This means that every base in the viral genome mutates to every other possible base, EVERY DAY |
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What is the primary treatment for HIV?
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Highly Active Anti-Retroviral Therapy (HAART). Usually 3 different drugs that work by different mechanisms
- multi drug regiment - Includes drugs that block protease (inhibits viral maturation), entry, integrase, and RT. |
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What are the steps in HIV entering a cell?
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1. HIV engages CD4 receptor via env (gp120)
2. Env then binds co-receptor (either CCR5 or CXCR4) 3. gp41 fusion peptide exposed, inserts into cell membrane 4. gp41 helical regions fold back on each other to bring membranes together, FUSION |
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What are the 4 classes of antiretroviral agents?
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1. RT Inhibitors
2. Protease Inhibitors 3. Integrase Inhibitors 4. Entry Inhibitors (NEW) |
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What are the 2 main measures of HIV disease progression?
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1. CD4+ T cell count (AIDS = <200)
2. Level of HIV RNA in plasma ("viral load") |
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What are the symptoms and characteristics of Acute HIV?
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- Occurs 2-6 wks following infection. Lasts 1-3 wks
- Mono like symptoms - Extremely highly circulating virus - GALT decimated. Bacteria enter bloodsteam. Immune response helps to spread HIV. - VERY INFECTIOUS during this time |
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What is the period following Acute HIV infection?
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Clinical Latency
- viral load decrease to ~30,000/ml - usually asymptomatic - CD4+ count slowly declines (7-10 years) |
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What polymorphism account for the "exposed-uninfected" individuals who do not contract HIV?
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delta32 - ccr5 polymorphism
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What are the 4 categories of HIV infected individuals (with regard to disease progression)?
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1. Exposed - Uninfected - ccr5 polymorphism
2. Rapid Progressors - progress to AIDS quickly, 1-3 years 3. Long term nonprogressors: 5% of ppl with HIV >20 years who don't progress to AIDS 4. Elite Controllers - subset of long term nonprogressors who have virus loads below level of detection |
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What are the cellular characteristics of HIV?
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- retrovirus
- enveloped - 2 copies of +ssRNA |
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What are the 2 types of RT inhibitors?
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1. Nucleoside RTI (NRTI) - look like nucleotides, but stop elongation when incorporated
2. Non-Nucleoside RTI (NNRTI) - bind to RT at a different site than NRTI Note: viruses resistant to NRTI can still be sensitive to NNRTIs |
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Why does drug recycling not work for HIV?
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Because HIV has latent reservoirs in memory cells that guarantee lifetime persistence/resistance
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How does HIV genotyping aid in treatment?
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- Doctors can know which strain of HIV the pt has, whether resistant.
- Prescribe Tx accordingly |
