Virus- HIV Flashcards
Which continent has the highest incidence (and prevalence) of AIDS?
Africa
What are the three major routes of HIV transmission?
- Sexual contact
- Vertical (mother to newborn) transmission
- Parenteral
What is the most common mode of HIV transmission on a global basis?
Heterosexual contact
What type of virus is HIV?
Human retrovirus of the lentivirus family
What test is used to screen for HIV infection?
Enzyme-linked immunosorbent assay (ELISA) looks for AB to viral proteins; ↑ sensitivity.
What test is used to confirm HIV(+) screening results?
Western blot assay (high false negative within 2 months of infection); ↑ specificity
Which enzyme creates dsDNA from RNA for integration into host genome?
Reverse transcriptase (RT)
What test is used to monitor the effects of antiretroviral therapy?
HIV RT-polymerase chain reaction (RT-PCR) (measures viral load)
What is the strongest measure of disease progression in an HIV(+) patient?
CD4+ T-cell count
Name two key glycoproteins on the surface of the HIV viral envelope:
- gp41 (fusion)
2. gp120 (attachment) proteins; together = gp160
Name two key HIV viral core proteins:
- p24 (nucleocapsid)
2. p17 (matrix protein)
Name three key HIV retroviral enzymes contained in the core:
- RT
- Integrase
- Protease (all encoded by pol gene)
Which viral antigen peaks within 2 months of infection, then rises again years later?
p24
What are the two cell surface molecules to which gpl20 must bind?
- CD4
2. A chemokine receptor (CCR5 or CXCR4)
HIV infects which three cell types?
- CD4+T cells
- Monocytes/macrophages
- Dendritic cells
The induction of what cellular transcription factor during an immune response leads to activation of transcription of HIV proviral DNA?
Nuclear factor-kappa B (NF-KB)
Protease inhibitors of HIV prevent cleavage of the protein product of what viral genes?
Gag and pol genes
What are the three mechanisms by which HIV-infected CD4+ T cells are lost?
- HIV cytopathic effect
- Apoptosis
- HlV-specific cytotoxic T-cell killing
What are the three stages of HIV infection?
- Acute retroviral infection
- Chronic phase
- AIDS
What is the surrogate measure of viral load in an HIV(+) patient?
HIV-1 RNA
What is the strongest measure of disease progression in AIDS?
CD4+ T-cell count
Which tissues are the major reservoirs of HIV-infected T cells and macrophages in patients?
- Lymph nodes
- Spleen
- Tonsils
Which cell type in the brain is infected by HIV?
Microglial cells
List the major immune abnormalities in AIDS:
- Decreased number of CD4+ T cells
- Decreased T-cell function
- Polyclonal activation of B cells
- Altered macrophage function
What is the clinical picture of direct viral disease from HIV?
Constitutional symptoms (weight loss, fever, fatigue, and night sweats) and/or neurologic symptoms (encephalopathy with dementia and aseptic meningitis)
How is AIDS defined?
CD4+ 200 or AIDS-defining illness, regardless of CD4+ count
Name the common AIDS opportunistic organisms or infections/diseases associated with the following:
Four fungal infections
- Candidiasis (GI tract)
- Cryptococcosis (meningitis)
- Histoplasmosis (disseminated)
- Coccidioidomycosis (disseminated)
Name the common AIDS opportunistic organisms or infections/diseases associated with the following:
Five bacterial infections
- Mycobacterium tuberculosis (lung/disseminated)
- Mycobacterium avium-intracellulare (lung)
- Nocardia (lung/CNS/disseminated)
- Salmonella (disseminated)
- Encapsulated organisms
Name the common AIDS opportunistic organisms or infections/diseases associated with the following:
Four viral infections
- HSV
- VZV (shingles)
- CMV (retinitis or colitis)
- JC virus (PML)
Name the common AIDS opportunistic organisms or infections/diseases associated with the following:
Three protozoal infections
- Pneumocystis (lung or disseminated)
- Toxoplasm (lung/CNS)
- Cryptosporidium (GI)
State the typical CD4+ count associated with each:
Opportunistic infections are typically seen, especially Pneumocystis jiroveci pneumonia
200 cells/mL
State the typical CD4+ count associated with each:
Mycobacterium avium complex (MAC), CMV, and cryptosporidiosis
50 cells/mL
State the typical CD4+ count associated with each:
Toxoplasmosis
100 cells/mL
State the typical CD4+ count associated with each:
TB becomes more common
400 cells/mL
List four common neoplasms in patients with AIDS:
- Kaposi sarcoma
- Non-Hodgkin B-cell lymphoma
- CNS lymphoma
- Squamous cell carcinoma of the cervix or anus
What has been shown to minimize the risk of perinatal HIV transmission?
Zidovudine (AZT) given to pregnant women, cesarean delivery, and avoiding breast feeding
