9 HIV Flashcards
HIV infection results in …
AIDS
Onset of HIV infection may be…
Asymptomatic
Or
Associated with a self-limited mono-like condition
When are HIV patients at highest risk of transmitting the infection?
Early-stage disease periods when patients have high virus loads but are unaware they have an infection
All HIV patients are considered to be lifelong…
Carriers, and continuously infectious
AIDS is diagnosed when CD4 T cell counts fall below ________ and severe damage to the immune system becomes evident
200 µL
_________ emerge as immune system fails
AIDs defining conditions - opportunistic infections, cancers, and conditions linked to AIDS
Examples of AIDS-defining conditions
Karposi’s sarcoma
MAC
Pneumocystis pneumonia
CMV
Development of AIDS usually lags behind HIV infection by about…
A decade
What are the different classes of disease course for HIV?
Fast - 3 years or less to AIDS
Intermediate - AIDS emergence after about 10 years
Long-term non-progressors - >10 years to AIDS, less than 5% of cases
Elite controllers
What type of virus is HIV?
Human retrovirus (lentivirus)
RNA genome
Enveloped virion
Reverse transcriptase (RNA dependent DNA polymerase) enzyme encoded by the virus
What are the origins of HIV?
An animal zoonosis that has entered human populations several times
Retrospective studies have found virus samples of serum dating to the 1950’s and an origin in chimpanzees and other non-human primates is postulated
Human population entry through primate bushmeat?
How does HIV infection occur?
Infection of cells with CD4 and a chemo kind co-receptor molecule displayed at surface
Th, monocytes, macrophages
How does HIV continue it’s infection?
Reverse transcriptase of viral genome —> integration into host chromosome (using viral integrase)
To complete life cycle, a DNA copy is made of the viral RNA genome and inserted into the host cell chromosome, and viral replication occurs using this copy
Latency is established (may be short)
Activation of latent virus follows and progeny production begins
Ultimately with HIV, _____ cell loss occurs in the patient and results in _____________.
Helper T cell
Profound immunosuppression
What complicates treatment for HIV?
The fast mutation rate - virus creates swarms of quasi-related subtypes in a single patient
Necessitates the use of combo chemotherapies to suppress infections
What are the primary mechanisms for transmission of HIV?
Sexual contact
Parenteral (IVDU, needle sticks) - NOT INSECT BITES
Perinatal (either in utero or postpartum)
Organ transplants
Occupational (low)
What enhances HIV infection probability during sexual contact?
Lesions of HSV or syphilis
________ is highly unlikely to result in HIV infection
Casual contact
The HIV virus has a worldwide distribution but there are ______ distinct types.
Two - HIV-1 and HIV-2
Many subtypes in circulation
Transmission in developing nations
Homosexuals
Bisexuals
IVDUsers and their sexual partners
Babies born to infected mothers
Transmission in Sub-Saharan Africa and some regions of Latin America/Caribbean
Heterosexual transfer dominates (mother-to-child infection is a big problem)
In the US, what population is presently showing the greatest rates of increase in HIV infection?
Heterosexuals
_____ is more common worldwide, while _____ is most prevalent in West Africa
HIV-1 worldwide
HIV-2 West Africa
What makes HIV-2 stand out?
Less transmissible
Slower progression to AIDS
Resistant to non-nucleoside reverse transcriptase inhibitors (NNRTIs)
Patient is maximally infectious at the ________ stage
Initial infection - before antibody response is in evidence
What pattern does the HIV virus follow after infection?
Rise, dip, return
Infection initiates, patient responds with antibodies, ultimate increase as the immune system collapses
A ______ system of diagnosis is employed to minimize improper diagnosis due to false positive reactions
Two-step
What is the typical infection screening approach?
Detection of anti-HIV antibody
- EIA screen to reveal anti-HIV antibodies in patient serum
- Western blot for confirmation - more specific, confirms the antibodies specifically bind to defined HIV virion antigens
The two step testing method will not reliably reveal patients with…
Recent infections, who have not yet had an antibody response to the infection
PCR-based tests that allow viral RNA to be detected directly
Nucleic Acid Tests (NAT)
Enables virus loads to be quantified even if patient has not yet responded with antibodies**
Donated blood is screened how?
Screened directly for the presence of HIV antigens (p24) or with RNA NAT
These are detectable earlier than the patient will initiate an antibody response - ruling out the possibility of contaminated blood from a donor who gave blood early in the course of infection
Rapid tests are used to detect…
HIV antibody
The hope is that more infections will be recognized sooner
What type of treatment approach do you have to take with HIV?
Simultaneous treatment with multiple agents, since HIV has such a high mutation rate
What are the two main categories of Reverse Transcriptase Inhibitors?
Nucleoside/tide analogs - competitive inhibitors that inhibit reverse transcriptase production of DNA by premature chain termination
Non-nucleoside reverse transcriptase inhibitors - bind to reverse transcriptase and inhibit enzyme activity
What HIV drugs are used to stop maturation/viral assembly
Protease inhibitors
What drugs are used to interfere with HIV entry into host by inhibiting the fusion of virus and host membranes?
Fusion-penetration inhibitors
What has made a remarkable difference in clinical condition of HIV patients?
Combinations of nucleotide analogs with protease inhibitors
Virus sinks to undetectable levels
The therapy is difficult for patients, but compliance is essential to avoid emergence of drug-resistance
It’s a therapy, not a cure
The future of HIV treatment:
Look for new _______ that block virus release from infected cell and _______ that half virus genome integration into the host genome
Maturation inhibitors
Integrase inhibitors
___________ may produce marked benefits by reducing emergence of opportunistic infections and threat from AIDS-associated cancers as well as drastically reducing the risk of HIV transmission
Starting HAART early
These tests reveal the amount of HIV in the blood
Viral load
Limit of detection for most tests is ca. 50 copies/ml
Load tests every ______ days or so for persons living with HIV, more frequently for persons early in treatment or prior to successful suppression
90 days
Effective treatment means counts are low. Follow trend of the counts to decide if new regimen is needed.
A substantial portion of HIV patients exhibit HIV-associated __________
Neurocognitive disorder (HAND)
May impact capacity to adhere to strict drug treatment regimens
What is our best method currently for preventing spread?
EDUCATION
Clean needle programs
Condoms
What does U=U mean?
Undetectable = Un-transmissible
Anti-retroviral therapies drive virus to undetectable levels where patients may not be infectious
How are we trying to stop HIV in the US?
Proactive efforts to identify HIV(+) persons with immediate treatment
Offering Pre-exposure prophylaxis (PrEP) to subjects at high risk
The opioid epidemic and IV drug use may thwart the effort
