HIV And AIDS Flashcards by Monica Kelley

What is the more common form of HIV?

Type 1 and is normally the one referred to in general

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What type of HIV is less infectious and will have slower progression?

Type 2

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What is the classification system that is used for HIV classification?

Groups :M, N, O, P

2. Subgroups: ABCDEFJK

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Where does HIV-1 originate from?

Pan troglodytes troglodytes (chimpanzee)

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Where does HIV-2 originate from?

Sooty mangabey monkey

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What is the structure of HIV?

2 positive strain of ssRNA, as a retrovirus

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What allow for the adsorption of HIV?

Glycoprotein gp120, on the surface of the HIV capsule

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What allows the HIV to penetrate cells after attaching with gp120?

Penetration with gp41 into the host membrane

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What is the serum indicator of the level of infection of HIV?

P24

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What can p24 tell about an individual?

The progression of HIV in patient serum

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What does the matrix protein (p17) do?

Forms the inner viral membrane and directs assembly of virus

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What is contained inside the viral membrane and will direct the formation of virus assembly?

P17 protein

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Are HIV-1 and HIV-2 immunologically cross-reactive?

No, due to difference in expression of envelope glycoproteins

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What are the structural genes of HIV?

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GAG is an HIV structural virus that encodes for what?

Capsid protein
Matrix protein
Nucleicapsid protein

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POL gene of HIV has what funciton?

Encodes reverse transcriptase
Protease
Integrase
Ribonuclease

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What does the ENV gene of HIV code for?

The envelopes glycoproteins

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What is a high affinity for gp120, which allows for attachment of HIV to host cells?

High affinity between gp120, and CD4

2. Confers infection with Th cells primarily

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What are co surface receptors for HIV?

CXCR4 and CCR5

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Where are CXCR4 and CCR5 most commonly expressed?

CD4 cells
DC
Macrophages

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How long is HIV able to survive outside of a cell?

Half-life is 6 hours

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What is the half-life of an HIV infected T cell?

1 day

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What are the major cellular reservoirs of HIV in the host?

Memory T cells

2. Macrophages

What happens when HIV settles inside a Th cell?

Produces a latent infection as the half life of the virus can be anywhere from months to years long.
The virus can remain dormant and “hide” until later dates

What happens when HIV settles within macrophages?

Also able to produce infection with a half-life of months to years.

What is required for activation of T cells in order for HIV to infect?

1. Only infects activated T cells. 2. Requires binding of CD4 to gp120/41 3. Co-binding with CCR5/CXCR4, which are only expressed on active T cells.

When does HIV become clinically manifested and is now represented as AIDS?

The infections switches from attacking the CD4 cells to attacking macrophages. 1. One theory is depletion of CD4 cells, causes virus to alter costimulatory binding proteins to attack macrophages.

How is HIV most commonly transmitted?

1. Sex 2. Vertical transmission (mother to fetus, in delivery or breast milk) 3. Drug use, contamination from body fluid or blood contact.

What can acute HIV infection be similar to?

Mononucleosis-like illness if 50%

When are symptoms common to begin to become present with acute HIV infection?

14 days of infection. Best diagnosis is 3-4 years after infection

How many stages does HIV have?

I, II, III, IV

What is stage I of HIV?

A symptomatic

What is stage II of HIV?

Mucocutaneous manifestations

What is stage III of HIV infection?

Chronic diarrhea, bacterial infections, Pulmonary TB

What is stage IV of HIV infection?

Toxoplasmosis of brain, candidiasis of lungs | Kaposi's sarcoma

Where will HIV establish reservoirs in the human body?

1. Tissue Macrophages 2. DC 3. Memory CD4 cells

HIV causes lack of memory CD4 T cells which will do what to immune response?

Will alter the initial/proper way immune system responds

Where will HIV undergo changes to adapt to the environment?

Common within macrophages as they are more resistant to cytoplasmic effects of HIV, and more common than the T cells.

What contributes to the long life span/infection of the HIV virus?

Primary reservoir is the macrophages, which are present in the body for lifetime. Unable to use cytoplasmic treatments, bc macrophages are resistant.

What indicates and infected individual that has progressed to develop AIDS?

flow cytometry results of 1:1 CD4:CD8 cells.

What is the normal ratio of CD8:CD4 cells?

1:2. CD8:CD4

What can be used to determine a quantitative analysis of AIDS/HIV?

1. Anti-CD4 Abs, will bind to the number of CD4+ T cells.

CD4+ cell destruction mark the point of AIDS. What can contribute to the formation of AIDS?

1. HIV (s/p infection) 2. Chronic immune activation--> CD4 apoptosis 3. ADCC killing of CD4 cell with gp120 4. CTL against CD4 cells 5. Bone marrow toxicity--> inhibit lymphocyte regeneration

What is the method HIV-1 uses to induce CD4 death with non-infected cells?

1. HIV increases FAS/FASL expression on non-infected cells, causing self destruction of CD4 cells via FAS/FASL mediated apoptosis

What is the primary result of HIV-1 infection of cells?

1. HIV-1 induced apoptosis of infected cells

If central memory CD4 T cells are resistant to HIV-1 infection, how are they destroyed?

1. Destroyed by virus induced cell death. Non-infected cells display increased amounts of FAS/FASL which will cause self-apoptosis

HIV-1 infection that becomes chronic affects what cells?

CD4+ T cells that are infected are killed by CTL (CD8+)

What is the CD8, CTL role during an HIV infection?

1. Acute: controls HIV viremia for 2-4wks | 2. Can contribute to persistent CD4 destruction once HIV is chronic

What are the targets of CTL for HIV?

CTL attack the gp120/41 proteins on HIV, to control acute viremia during 2-4wk

What are the different functions of the humor anti-HIV Abs?

1. Neutralize the Ag 2. Opsonization the Ag 3. Ab-dependent cellular cytotoxicity

What allows the HIV the ability to maintain persistent infection even with treatment with multiple drugs?

1. Viral envelope undergoes variety of epitope changes.

The down side of using anti-HIV Ab therapy are what?

1. Opsonization: leads to increased uptake of macrophages. Providing new site for viral replication. 2. Reduced Ab concentration, "increases" the number of viruses that can bind to the host cells membrane.

What are the effect of reduced CD4 T cells in the immunosuppressive of AIDS?

1. Low B/t cell proliferation to Ags 2. Reduced resistance to intra-/extracellular pathogens 3. Altered B cell response (vaccine or Ag presentation)

What will ELISA testing detect for HIV?

Detect presence of Abs for p24 protein

How will PCR detect the presence of HIV??

Breakdown, and amplify the presence of certain proteins. Presence of p24 indicate quantitative level of HIV infection and progressive stages

What is the primary difference between the different types of HIV virus?

- type 1 - type 2 * differ by 40% genetic