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84 Cards in this Set

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  • Back
Approx how many people in the world have HIV? Where do most live?
40 million

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