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HIV and HTLV Flashcards

1
Q

What kind of virus is HIV?

A

RNA retrovirus

Uses reverse transcriptase to convert RNA to DNA

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2
Q

What cells do HIV infect?

A

CD4+ T-Helper Cells

Also macrophages

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3
Q

What kind of genome does HIV have?

A

Diploid: Carries two copies of (+) stranded RNA

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4
Q

RNA is tightly bound to what key enzymes

A

Reverse Transcriptase: Makes DNA from RNA
Aspartate Protease: Cleavage of Proteins
Integrase: Integrate DNA into host cell DNA

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5
Q

Describe capsid of HIV.

A

Cone-shaped (conical) capsid

  • Composed of multiple copies of p24 proteins
  • Non-variable protein structure as virus replicates
  • Antibody response can be generated but it is not strong enough to neutralize virus
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6
Q

What is the significance of p24 protein?

A

Antibodies for p24 can be used to detect HIV infection.

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7
Q

Is HIV naked or enveloped?

A

HIV is enveloped by by phospholipid from human cell membrane.

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8
Q

What protein is in HIV envelope?

A

Env protein

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9
Q

What glycoproteins does the cap of the env protein contain?

A

gp120: Attachment to T cells
gp41: Fusion and entry into T cells
Both formed as a single protein (gp160) and cleaved to become two smaller proteins (gp120 and gp41)

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10
Q

What accessory genes are necessary for HIV to replicate?

A

tat: activates gene transcription
rev: transports mRNA from nucleus to cytoplasm

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11
Q

Gene for gp120

A

Mutates rapidly (antigenic variation)
V3 loop portion is highly immunogenic (antibodies will be built against this portion)
Varies significantly during reproduction so antibody neutralization is difficult

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12
Q

gp120 glycoprotein is for

A

docking

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13
Q

gp41 transmembrane glycoprotein is for

A

fusion and entry

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14
Q

What are the 3 main genes that encode for HIV?

A

Gag: nucleocapsid
Pol: polymerase
Env: envelope proteins

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15
Q

What are auxilliary genes?

A

Genes not required for replication
Nef, viv, vpr, vpu, vpx
Nef: decreases CD4 proteins and MHC I on T-cell surfaces

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16
Q

CCR5 and CXCR4

A

Major lymphocyte receptors used by HIV to enter cells

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17
Q

CCR5-tropic viruses

A

Replicate in monocytes/macrophages (M-tropic)
Can also infect dendritic cells to traffick into lymph nodes (contain many CD4 cells -replication site)
Occur early: sexually transmitted to monocytes and macrophages in epithelial layer or urogenital tract

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18
Q

CXCR4-tropic viruses

A

Replicate more efficiently in T cells

Occur later after infection has developed

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19
Q

Mutations in which gene is associated with decreased susceptibility to HIV infection?

A

CCR5

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20
Q

Describe pathophysiology of HIV.

A
  1. HIV attacks cells that have CD4 on their surfaces
  2. gp120 (HIV surface glycoprotein) and CD4 bind
  3. gp120 then binds to co-receptor (either CCR5 or CXCR4)
  4. gp41 can now serve role as anchoring protein
  5. HIV can now gain entry into cell
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21
Q

The glycoproteins on the surface of HIV are

A

gp120 with variable loop regions

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22
Q

What cells have CD4 on their surfaces?

A

T cells, monocytes, macrophages, dendritic cells

-All cell types that HIV can infect

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23
Q

HIV-1

A

Causes majority of infection worldwide

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24
Q

HIV-2

A

Important cause of infection in West Africa

25
Why do NNRTIs not affect HIV-2?
HIV-2 has a different reverse transcriptase
26
What is typical progressor?
Pt not being treated with drugs
27
CD4 T-cell count
Determined by flow cytometry Normal = 1000cells/mm^3 AIDS < 200 Used to initiate prophylaxis against opportunistic infections
28
Lower set point =
Lower level of viremia -better prognosis for pt
29
HA, muscle aches, sore throat, fever, and swollen LN (flu-like sx) are due to
cytokine storm
30
Diarrhea or other GI complaints are due to
Infection of GALT cells
31
Macrophage is a professional
APC (antigen presenting cell)
32
Macrophages present antigen peptides to T-cells in the form of
MHC
33
T-cells generate cytokines that activate
B cells
34
B cells differentiate into
plasma cells
35
Plasma cells generate
antibodies
36
CD4 T-cells secrete cytokines cytotoxic T cells which go after
Virus-infected cells
37
Protozoal Opportunistic Infections
Toxoplasmosis, Crytosporidosis
38
Fungal Opportunistic Infections
Pneumocystis jiroveci Candidiadis, Crytococcosus Histoplasmosis, Coccidiomycosis
39
Opportunistic Bacterial Infections
Mycobacterium avium complex Atypical mycobacterial disease Salmonella septicemia Multiple or recurrent pyogenic bacterial infection
40
Viral Opportunistic Infections
CMV, HSV, VZV, EBV, JC virus (PML)
41
Time between infection and onset of AIDs in typical progressor
10 years
42
Time between infection and onset of AIDs in rapid progressor
2-3 years
43
Viral Load
Quantification of HIV RNA | Used to monitor effect of drug therapy
44
Initial HIV infection is asymptomatic in
10-60% of people
45
Acute HIV syndrome
2-4 weeks after exposure Fever, myalgias, sore throat, cervical adenopathy Sometimes maculopapular rash Similar to mononucleosis, EBV
46
Severe immunosuppression
Occurs after acute infection and latency period. | Symptoms from opportunistic infections secondary to low CD4 count.
47
Clinical Latency Period
Body is fighting virus but pt has no sx | CD8 T-cells
48
Rare HIV features
Dementia: Virus infects macrophages to get into CNS. Also can infect microglial cells. Pulmonary hypertension Cardiomyopathy and HF
49
ELISA Test
Screens for antibodies. Sensitive but many false positives.
50
Western blot
Confirmatory for positive ELISA test. Specific.
51
CDC Testing Recommendations
Combination antigen/antibody tests = 4th generation tests | Test for both p24 antigen and HIV antibodies
52
HIV-1/HIV-2 antibody differentiation assay
Done if 4th generation test is positive
53
For acute HIV (febrile mononucleosis-like illness) you can test for
``` HIV RNA (viral load) p24 is not present yet ```
54
Congenital HIV Test
PCR for babies b/c maternal HIV antibodies persist for months
55
TMP-SMX
Prophylactic treatment for pneumonia caused by Pneumocystis jiroveci CD4 count less than 200
56
Histoplasmosis occurs in
Mississippi and Ohio River valleys
57
Newer guidelines recommend treating
All patients
58
HAART =
Highly Active Antiretroviral Therapy

ID (13 decks)

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