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84 Cards in this Set
- Front
- Back
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Approx how many people in the world have HIV? Where do most live?
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40 million
-Most in africa (25 million) |
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How many people in north america have HIV?
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About 1 million
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How many new HIV cases are contracted each year
-In the world -In the North america |
World: 5 million
US: 50,000 |
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What are the 2 highest risk factors for getting HIV, in either males or females?
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-Risky sexual contact
-Injection drug use |
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What population has the highest HIV prevalance rate in the US?
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African american males
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What is the average age of HIV diagnosis in males and females?
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mid 30s (25-44 yrs)
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In what 4 infectious fluids can HIV be transmitted?
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1. Blood
2. Semen 3. Vaginal fluids 4. Breast milk |
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What are the routes of transmission of Blood?
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-Parental
-Vertical (mom to child) |
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What are the routes of transmission of Semen?
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Sexual
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What exactly are the 2 ways that HIV can be transmitted during sex?
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1. Blood vessel trauma
2. Macrophages in mucosal surfaces |
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What are the 2 routes of transmitting HIV in vaginal fluids?
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1. Sexual
2. Vertical |
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How is breast milk transmitted?
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Vertically
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What kind of a virus is the HIV virus?
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Retrovirus
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What is the easily detectable capsid protein on the HIV virus?
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p24
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What is inside an HIV virus?
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-2 copies of RNA
-Viral enzymes |
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What are the characteristics on its surface?
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GP120 (sitting on top of)
GP41 |
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What enzymes does HIV carry?
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-Integrase
-Reverse transcriptase -Protease |
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Where does the HIV life cycle occur?
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In WBCs:
-Tcells -DCs -Macrophages |
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What are the initial cells that HIV infects?
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-Macrophages in GI mucosa
-Tcells in the blood |
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How does HIV get established in lymphatic tissue?
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When the cells that initially ingest it migrate to lymph tissues.
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For what WBC receptor does HIV's GP 120 have high affinity?
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CD4 on Thelper cells
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What is required for HIV to bind to the CD4+ WBC?
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A coreceptor
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What is the coreceptor for HIV binding to Thelpers?
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CCR5 or CXCR4
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What molecule on HIV binds to the CCR5 or CXCR4?
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GP41
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What does stable binding of the HIV to surface proteins on Thelper cells allow?
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-Fusion of the virus with the cell membrane
-Entry of viral contents into the cytoplasm |
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What is the result of having a genetic absence of CCR5?
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No HIV infection with CCR5-tropic virus!
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What happens once the HIV virus gets inside a Thelper cell?
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Reverse transcription of the viral RNA to make cDNA
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What happens to he cDNA
-While the cell is quiescent -When the cell undergoes division |
Quiescent: remains in cytoplasm
Dividing: cDNA enters nucleus |
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What allows HIV viral cDNA to be integrated into the host genome during cell division?
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Integrase
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What happens when Thelper cells are activated by other infections or viruses?
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The viral dna will now get transcribed using the host's machinery, creating new baby viruses that bud off from the host cell memrane.
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What enzyme is required for viral particles to bud off from the host cell membrane?
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Protease
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What is the result of viral budding to CD4 cells?
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Cell death
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So in someone infected with HIV, how many viruses are produced daily?
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100 billion!
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How many CD4+ Tcells die daily due to HIV infection?
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1-2 billion
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What is the result of all those thelper cells dying?
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Immune suppression
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What cells other than mature CD4+ Tcells are affected by the virus?
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Progenitor cells in the thymus.
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What are the 3 main immunologic consequences of HIV infection?
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1. Lymphopenia
2. Decreased Tcell function 3. Altered Tcell function in vitro |
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What type of cell is deficient that causes the neutropenia?
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CD4 cells selectively
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Why is there decreased Tcell function seen in the patient?
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Because of the loss of memory Tcells
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What 2 things do HIV patients become susceptible to as a result of immune deficiency?
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-Opportunistic infections
-Neoplasms |
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What cells actually RESIST the cytopathic effects of HIV?
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Macrophages
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What do macrophages allow for HIV?
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They serve as a reservoir for infection and transfer it to the CNS.
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When HIV enters the host, where does it go initially?
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To lymph nodes
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What is the result of the initial replication of the virus in lymph nodes and large outpouring into the bloodstream?
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Acute retroviral syndrome
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When does acute retroviral syndrome occur?
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2-6 weeks after the initial viral transmission event
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What IS acute retroviral syndrome in a nutshell?
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The primary immune response to infection.
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What do the symptoms of acute retroviral syndrome usually look like?
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The flu or mono; fever, loss of appetite, etc.
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What occurs as a result of the high levels of viremia that occur in acute retroviral syndrome?
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Widespread seeding of other lymph tissue
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What type of cell-mediated immune mechanisms are going on or changing during acute retroviral syndrome?
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-CD4 thelper cells decrease, though not severely
-the CD8 CTL response contains the infection |
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When is an Antibody to HIV formed?
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4 weeks after the infection occurs
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So what is the best test for a person that fears HIV exposure within the past 4 weeks?
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RNA testing
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What is the best test after 4 weeks post exposure?
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Antibody
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What are the 4 phases of HIV infection?
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1. Acute Retroviral syndrome
2. Early HIV infection 3. Chronic HIV infection 4. Late HIV infection |
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What are the 3 main things to note about Early HIV infection?
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1. Seroconversion occurs
2. CD4 cells go back up 3. Viral load reaches equilibrium |
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What happens during Chronic phase HIV?
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-the virus is contained and clinically latent
-HIV continues to replicate in lymphoid tissues |
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What types of symptoms will be seen in chronic HIV?
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-May be asymptomatic
-Lymphadenopathy -Fatigue |
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What is happening to the Tcells during chronic HIV?
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-CTLs continue to remain active and responding
-CD4 thelpers have extensive turnover |
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What happens to the initial Large Regenerative capacity of the CD4 count as chronic HIV continues?
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It goes down and the person becomes immunosuppressed.
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So what are the 2 main things seen in the Late phase of HIV infection?
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-CD4 decline
-Increased plasma viral load |
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So what is the main screening test for HIV?
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Testing for the presence of antibody to HIV after seroconversion
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What method is used for this antibody testing?
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ELISA
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How long is the ELISA negative after infection?
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4-6 weeks
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Is rapid testing available?
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YEs
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What is the confirmatory test for HIV? Why?
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Western blot - it's more specific and will have fewer false positives.
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What tests can be done 10-14 days after possible transmission?
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-HIV viral load
-p24 antigen testing |
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What is HIV screening?
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Testing people who have no suspicion that they have it
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What are the 3 goals of HIV screening?
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1. Treatment of HIV pos pts
2. Decreased HIV transmission 3. Prevention of perinatal HIV transmission |
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What patients should be screened at least once?
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-Anyone between 13-64
-Any pregnant patient |
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What patients should be tested annually?
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-IV drug users
-Commercial sex workers -Persons with >1 sexual partner since their last HIV test |
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What is done with an HIV patient on their initial encounter?
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-Thorough patient history
-HIV prevention counseling -Physical exam -baseline testing |
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What percentage of patients for whom AIDs testing is indicated do not have it available to them?
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70%
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What has happened to antiretroviral therapy in the last decade?
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Many new agents have been made
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What has resulted from having better medicines and knowledge of how to use meds more effectively?
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A dramatic decrease in the number of deaths due to AIDS
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How long will a person live who is infected and diagnosed with HIV at age 25?
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Probably about 65
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How can a person survive that long?
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Because of the late HAART era - highly active anti-retroviral therapy.
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If a mom is HIV infected, what are the chances of her passing on the infection to the neonate?
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25%
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What drug is used to prevent perinatal transmission?
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AZT
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What are the chances of passing on HIV vertically if one drug is used?
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8%
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What reduces the chance of HIV transmission down to 0-1%?
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Giving HAART starting in the 2nd trimester, IV AZT during labor, and AZT to the baby for six weeks. Also give formula instead of mother's milk.
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What is HAART?
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Triple therapy
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What is the rule of 3's for needlestick exposures?
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In one needle stick the risk of getting
Hep B is 30% Hep C is 3% HIV is .3% |
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What should be done after a needlestick to prevent HIV infection?
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PEP
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What is PEP?
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Post exposure prophylaxis
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What is the current standard for PEP?
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A 2 or 3 drug regimen
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