HIV And AIDS Flashcards
What is the more common form of HIV?
Type 1 and is normally the one referred to in general
What type of HIV is less infectious and will have slower progression?
Type 2
What is the classification system that is used for HIV classification?
- Groups :M, N, O, P
2. Subgroups: ABCDEFJK
Where does HIV-1 originate from?
- Pan troglodytes troglodytes (chimpanzee)
Where does HIV-2 originate from?
- Sooty mangabey monkey
What is the structure of HIV?
2 positive strain of ssRNA, as a retrovirus
What allow for the adsorption of HIV?
Glycoprotein gp120, on the surface of the HIV capsule
What allows the HIV to penetrate cells after attaching with gp120?
Penetration with gp41 into the host membrane
What is the serum indicator of the level of infection of HIV?
P24
What can p24 tell about an individual?
The progression of HIV in patient serum
What does the matrix protein (p17) do?
Forms the inner viral membrane and directs assembly of virus
What is contained inside the viral membrane and will direct the formation of virus assembly?
P17 protein
Are HIV-1 and HIV-2 immunologically cross-reactive?
No, due to difference in expression of envelope glycoproteins
What are the structural genes of HIV?
- GAG
- POL
- ENV
GAG is an HIV structural virus that encodes for what?
- Capsid protein
- Matrix protein
- Nucleicapsid protein
POL gene of HIV has what funciton?
- Encodes reverse transcriptase
- Protease
- Integrase
- Ribonuclease
What does the ENV gene of HIV code for?
- The envelopes glycoproteins
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
What are co surface receptors for HIV?
CXCR4 and CCR5
Where are CXCR4 and CCR5 most commonly expressed?
- CD4 cells
- DC
- Macrophages
How long is HIV able to survive outside of a cell?
Half-life is 6 hours
What is the half-life of an HIV infected T cell?
1 day
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?
- Only infects activated T cells.
- Requires binding of CD4 to gp120/41
- 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?
- Sex
- Vertical transmission (mother to fetus, in delivery or breast milk)
- 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?
- Tissue Macrophages
- DC
- 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?
- 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?
- HIV (s/p infection)
- Chronic immune activation–> CD4 apoptosis
- ADCC killing of CD4 cell with gp120
- CTL against CD4 cells
- Bone marrow toxicity–> inhibit lymphocyte regeneration
What is the method HIV-1 uses to induce CD4 death with non-infected cells?
- 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?
- HIV-1 induced apoptosis of infected cells
If central memory CD4 T cells are resistant to HIV-1 infection, how are they destroyed?
- 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?
- 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?
- Neutralize the Ag
- Opsonization the Ag
- Ab-dependent cellular cytotoxicity
What allows the HIV the ability to maintain persistent infection even with treatment with multiple drugs?
- Viral envelope undergoes variety of epitope changes.
The down side of using anti-HIV Ab therapy are what?
- Opsonization: leads to increased uptake of macrophages. Providing new site for viral replication.
- 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?
- Low B/t cell proliferation to Ags
- Reduced resistance to intra-/extracellular pathogens
- 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
