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Microbiology Unit 3 > 9 HIV > Flashcards

9 HIV Flashcards

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Biology 101 flashcards
1
Q

HIV infection results in …

A

AIDS

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2
Q

Onset of HIV infection may be…

A

Asymptomatic

Or

Associated with a self-limited mono-like condition

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3
Q

When are HIV patients at highest risk of transmitting the infection?

A

Early-stage disease periods when patients have high virus loads but are unaware they have an infection

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4
Q

All HIV patients are considered to be lifelong…

A

Carriers, and continuously infectious

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5
Q

AIDS is diagnosed when CD4 T cell counts fall below ________ and severe damage to the immune system becomes evident

A

200 µL

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6
Q

_________ emerge as immune system fails

A

AIDs defining conditions - opportunistic infections, cancers, and conditions linked to AIDS

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7
Q

Examples of AIDS-defining conditions

A

Karposi’s sarcoma

MAC

Pneumocystis pneumonia

CMV

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8
Q

Development of AIDS usually lags behind HIV infection by about…

A

A decade

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9
Q

What are the different classes of disease course for HIV?

A

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

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10
Q

What type of virus is HIV?

A

Human retrovirus (lentivirus)

RNA genome

Enveloped virion

Reverse transcriptase (RNA dependent DNA polymerase) enzyme encoded by the virus

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11
Q

What are the origins of HIV?

A

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?

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12
Q

How does HIV infection occur?

A

Infection of cells with CD4 and a chemo kind co-receptor molecule displayed at surface

Th, monocytes, macrophages

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13
Q

How does HIV continue it’s infection?

A

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

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14
Q

Ultimately with HIV, _____ cell loss occurs in the patient and results in _____________.

A

Helper T cell

Profound immunosuppression

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15
Q

What complicates treatment for HIV?

A

The fast mutation rate - virus creates swarms of quasi-related subtypes in a single patient

Necessitates the use of combo chemotherapies to suppress infections

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16
Q

What are the primary mechanisms for transmission of HIV?

A

Sexual contact
Parenteral (IVDU, needle sticks) - NOT INSECT BITES
Perinatal (either in utero or postpartum)
Organ transplants
Occupational (low)

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17
Q

What enhances HIV infection probability during sexual contact?

A

Lesions of HSV or syphilis

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18
Q

________ is highly unlikely to result in HIV infection

A

Casual contact

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19
Q

The HIV virus has a worldwide distribution but there are ______ distinct types.

A

Two - HIV-1 and HIV-2

Many subtypes in circulation

20
Q

Transmission in developing nations

A

Homosexuals
Bisexuals
IVDUsers and their sexual partners
Babies born to infected mothers

21
Q

Transmission in Sub-Saharan Africa and some regions of Latin America/Caribbean

A

Heterosexual transfer dominates (mother-to-child infection is a big problem)

22
Q

In the US, what population is presently showing the greatest rates of increase in HIV infection?

A

Heterosexuals

23
Q

_____ is more common worldwide, while _____ is most prevalent in West Africa

A

HIV-1 worldwide

HIV-2 West Africa

24
Q

What makes HIV-2 stand out?

A

Less transmissible

Slower progression to AIDS

Resistant to non-nucleoside reverse transcriptase inhibitors (NNRTIs)

25
Q

Patient is maximally infectious at the ________ stage

A

Initial infection - before antibody response is in evidence

26
Q

What pattern does the HIV virus follow after infection?

A

Rise, dip, return

Infection initiates, patient responds with antibodies, ultimate increase as the immune system collapses

27
Q

A ______ system of diagnosis is employed to minimize improper diagnosis due to false positive reactions

A

Two-step

28
Q

What is the typical infection screening approach?

A

Detection of anti-HIV antibody

  1. EIA screen to reveal anti-HIV antibodies in patient serum
  2. Western blot for confirmation - more specific, confirms the antibodies specifically bind to defined HIV virion antigens
29
Q

The two step testing method will not reliably reveal patients with…

A

Recent infections, who have not yet had an antibody response to the infection

30
Q

PCR-based tests that allow viral RNA to be detected directly

A

Nucleic Acid Tests (NAT)

Enables virus loads to be quantified even if patient has not yet responded with antibodies**

31
Q

Donated blood is screened how?

A

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

32
Q

Rapid tests are used to detect…

A

HIV antibody

The hope is that more infections will be recognized sooner

33
Q

What type of treatment approach do you have to take with HIV?

A

Simultaneous treatment with multiple agents, since HIV has such a high mutation rate

34
Q

What are the two main categories of Reverse Transcriptase Inhibitors?

A

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

35
Q

What HIV drugs are used to stop maturation/viral assembly

A

Protease inhibitors

36
Q

What drugs are used to interfere with HIV entry into host by inhibiting the fusion of virus and host membranes?

A

Fusion-penetration inhibitors

37
Q

What has made a remarkable difference in clinical condition of HIV patients?

A

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

38
Q

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

A

Maturation inhibitors

Integrase inhibitors

39
Q

___________ 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

A

Starting HAART early

40
Q

These tests reveal the amount of HIV in the blood

A

Viral load

Limit of detection for most tests is ca. 50 copies/ml

41
Q

Load tests every ______ days or so for persons living with HIV, more frequently for persons early in treatment or prior to successful suppression

A

90 days

Effective treatment means counts are low. Follow trend of the counts to decide if new regimen is needed.

42
Q

A substantial portion of HIV patients exhibit HIV-associated __________

A

Neurocognitive disorder (HAND)

May impact capacity to adhere to strict drug treatment regimens

43
Q

What is our best method currently for preventing spread?

A

EDUCATION

Clean needle programs

Condoms

44
Q

What does U=U mean?

A

Undetectable = Un-transmissible

Anti-retroviral therapies drive virus to undetectable levels where patients may not be infectious

45
Q

How are we trying to stop HIV in the US?

A

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

Microbiology Unit 3 (10 decks)

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