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ID > HIV and HTLV > Flashcards

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
Q

Why do NNRTIs not affect HIV-2?

A

HIV-2 has a different reverse transcriptase

26
Q

What is typical progressor?

A

Pt not being treated with drugs

27
Q

CD4 T-cell count

A

Determined by flow cytometry
Normal = 1000cells/mm^3
AIDS < 200
Used to initiate prophylaxis against opportunistic infections

28
Q

Lower set point =

A

Lower level of viremia -better prognosis for pt

29
Q

HA, muscle aches, sore throat, fever, and swollen LN (flu-like sx) are due to

A

cytokine storm

30
Q

Diarrhea or other GI complaints are due to

A

Infection of GALT cells

31
Q

Macrophage is a professional

A

APC (antigen presenting cell)

32
Q

Macrophages present antigen peptides to T-cells in the form of

A

MHC

33
Q

T-cells generate cytokines that activate

A

B cells

34
Q

B cells differentiate into

A

plasma cells

35
Q

Plasma cells generate

A

antibodies

36
Q

CD4 T-cells secrete cytokines cytotoxic T cells which go after

A

Virus-infected cells

37
Q

Protozoal Opportunistic Infections

A

Toxoplasmosis, Crytosporidosis

38
Q

Fungal Opportunistic Infections

A

Pneumocystis jiroveci
Candidiadis, Crytococcosus
Histoplasmosis, Coccidiomycosis

39
Q

Opportunistic Bacterial Infections

A

Mycobacterium avium complex
Atypical mycobacterial disease
Salmonella septicemia
Multiple or recurrent pyogenic bacterial infection

40
Q

Viral Opportunistic Infections

A

CMV, HSV, VZV, EBV, JC virus (PML)

41
Q

Time between infection and onset of AIDs in typical progressor

A

10 years

42
Q

Time between infection and onset of AIDs in rapid progressor

A

2-3 years

43
Q

Viral Load

A

Quantification of HIV RNA

Used to monitor effect of drug therapy

44
Q

Initial HIV infection is asymptomatic in

A

10-60% of people

45
Q

Acute HIV syndrome

A

2-4 weeks after exposure
Fever, myalgias, sore throat, cervical adenopathy
Sometimes maculopapular rash
Similar to mononucleosis, EBV

46
Q

Severe immunosuppression

A

Occurs after acute infection and latency period.

Symptoms from opportunistic infections secondary to low CD4 count.

47
Q

Clinical Latency Period

A

Body is fighting virus but pt has no sx

CD8 T-cells

48
Q

Rare HIV features

A

Dementia: Virus infects macrophages to get into CNS. Also can infect microglial cells.
Pulmonary hypertension
Cardiomyopathy and HF

49
Q

ELISA Test

A

Screens for antibodies. Sensitive but many false positives.

50
Q

Western blot

A

Confirmatory for positive ELISA test. Specific.

51
Q

CDC Testing Recommendations

A

Combination antigen/antibody tests = 4th generation tests

Test for both p24 antigen and HIV antibodies

52
Q

HIV-1/HIV-2 antibody differentiation assay

A

Done if 4th generation test is positive

53
Q

For acute HIV (febrile mononucleosis-like illness) you can test for

A 
HIV RNA (viral load)
p24 is not present yet
54
Q

Congenital HIV Test

A

PCR for babies b/c maternal HIV antibodies persist for months

55
Q

TMP-SMX

A

Prophylactic treatment for pneumonia caused by Pneumocystis jiroveci
CD4 count less than 200

56
Q

Histoplasmosis occurs in

A

Mississippi and Ohio River valleys

57
Q

Newer guidelines recommend treating

A

All patients

58
Q

HAART =

A

Highly Active Antiretroviral Therapy

ID (13 decks)

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