Virus- HIV

Question 1

Which continent has the highest incidence (and prevalence) of AIDS?

Answer 1

Africa

Question 2

What are the three major routes of HIV transmission?

Answer 2

1. Sexual contact
2. Vertical (mother to newborn) transmission
3. Parenteral

Question 3

What is the most common mode of HIV transmission on a global basis?

Answer 3

Heterosexual contact

Question 4

What type of virus is HIV?

Answer 4

Human retrovirus of the lentivirus family

Question 5

What test is used to screen for HIV infection?

Answer 5

Enzyme-linked immunosorbent assay (ELISA) looks for AB to viral proteins; ↑ sensitivity.

Question 6

What test is used to confirm HIV(+) screening results?

Answer 6

Western blot assay (high false negative within 2 months of infection); ↑ specificity

Question 7

Which enzyme creates dsDNA from RNA for integration into host genome?

Answer 7

Reverse transcriptase (RT)

Question 8

What test is used to monitor the effects of antiretroviral therapy?

Answer 8

HIV RT-polymerase chain reaction (RT-PCR) (measures viral load)

Question 9

What is the strongest measure of disease progression in an HIV(+) patient?

Answer 9

CD4+ T-cell count

Question 10

Name two key glycoproteins on the surface of the HIV viral envelope:

Answer 10

1. gp41 (fusion)

2. gp120 (attachment) proteins; together = gp160

Question 11

Name two key HIV viral core proteins:

Answer 11

1. p24 (nucleocapsid)

2. p17 (matrix protein)

Question 12

Name three key HIV retroviral enzymes contained in the core:

Answer 12

1. RT
2. Integrase
3. Protease (all encoded by pol gene)

Question 13

Which viral antigen peaks within 2 months of infection, then rises again years later?

Answer 13

p24

Question 14

What are the two cell surface molecules to which gpl20 must bind?

Answer 14

1. CD4

2. A chemokine receptor (CCR5 or CXCR4)

Question 15

HIV infects which three cell types?

Answer 15

1. CD4+T cells
2. Monocytes/macrophages
3. Dendritic cells

Question 16

The induction of what cellular transcription factor during an immune response leads to activation of transcription of HIV proviral DNA?

Answer 16

Nuclear factor-kappa B (NF-KB)

Question 17

Protease inhibitors of HIV prevent cleavage of the protein product of what viral genes?

Answer 17

Gag and pol genes

Question 18

What are the three mechanisms by which HIV-infected CD4+ T cells are lost?

Answer 18

1. HIV cytopathic effect
2. Apoptosis
3. HlV-specific cytotoxic T-cell killing

Question 19

What are the three stages of HIV infection?

Answer 19

1. Acute retroviral infection
2. Chronic phase
3. AIDS

Question 20

What is the surrogate measure of viral load in an HIV(+) patient?

Answer 20

HIV-1 RNA

Question 21

What is the strongest measure of disease progression in AIDS?

Answer 21

CD4+ T-cell count

Question 22

Which tissues are the major reservoirs of HIV-infected T cells and macrophages in patients?

Answer 22

1. Lymph nodes
2. Spleen
3. Tonsils

Question 23

Which cell type in the brain is infected by HIV?

Answer 23

Microglial cells

Question 24

List the major immune abnormalities in AIDS:

Answer 24

1. Decreased number of CD4+ T cells
2. Decreased T-cell function
3. Polyclonal activation of B cells
4. Altered macrophage function

Question 25

What is the clinical picture of direct viral disease from HIV?

Answer 25

Constitutional symptoms (weight loss, fever, fatigue, and night sweats) and/or neurologic symptoms (encephalopathy with dementia and aseptic meningitis)

Question 26

How is AIDS defined?

Answer 26

CD4+ 200 or AIDS-defining illness, regardless of CD4+ count

Question 27

Name the common AIDS opportunistic organisms or infections/diseases associated with the following: Four fungal infections

Answer 27

1. Candidiasis (GI tract) 2. Cryptococcosis (meningitis) 3. Histoplasmosis (disseminated) 4. Coccidioidomycosis (disseminated)

Question 28

Name the common AIDS opportunistic organisms or infections/diseases associated with the following: Five bacterial infections

Answer 28

1. Mycobacterium tuberculosis (lung/disseminated) 2. Mycobacterium avium-intracellulare (lung) 3. Nocardia (lung/CNS/disseminated) 4. Salmonella (disseminated) 5. Encapsulated organisms

Question 29

Name the common AIDS opportunistic organisms or infections/diseases associated with the following: Four viral infections

Answer 29

1. HSV 2. VZV (shingles) 3. CMV (retinitis or colitis) 4. JC virus (PML)

Question 30

Name the common AIDS opportunistic organisms or infections/diseases associated with the following: Three protozoal infections

Answer 30

1. Pneumocystis (lung or disseminated) 2. Toxoplasm (lung/CNS) 3. Cryptosporidium (GI)

Question 31

State the typical CD4+ count associated with each: Opportunistic infections are typically seen, especially Pneumocystis jiroveci pneumonia

Answer 31

200 cells/mL

Question 32

State the typical CD4+ count associated with each: Mycobacterium avium complex (MAC), CMV, and cryptosporidiosis

Answer 32

50 cells/mL

Question 33

State the typical CD4+ count associated with each: Toxoplasmosis

Answer 33

100 cells/mL

Question 34

State the typical CD4+ count associated with each: TB becomes more common

Answer 34

400 cells/mL

Question 35

List four common neoplasms in patients with AIDS:

Answer 35

1. Kaposi sarcoma 2. Non-Hodgkin B-cell lymphoma 3. CNS lymphoma 4. Squamous cell carcinoma of the cervix or anus

Question 36

What has been shown to minimize the risk of perinatal HIV transmission?

Answer 36

Zidovudine (AZT) given to pregnant women, cesarean delivery, and avoiding breast feeding