HIV Flashcards
What is the structure of HIV?
Diploid genome - 2 molecules of +ssRNA, enveloped
What are the three structural genes of HIV?
env, gag, pol
What does env code for?
gp120 and gp41: Formed from cleavage of gp160 to form envelope glycoproteins
What does gp120 do?
Docking glycoprotein- Attaches to host CD4+ T cell
What does gp41 do?
Transmembrane protein that Fusion and entry into host cell
What does gag code for?
p24 - capsid protein
What does pol code for?
reverse transcriptase; synthesizes dsDNA from genomic RNA, which then integrates into host chromosome
What does HIV bind?
CD4 as well as coreceptor - CCR5 on macs (early infection), CXCR4 on T cells (late infection)
What protein mutation can confer immunity to HIV infection?
CCR5. Homozyg = immune. Heterozyg = slower course.
What are tat and rev?
Two regulatory genes required for transcription.
What is the ELISA test forHIV used for?
Presumptive diagnosis - it is a rule-out test, a sensitive test with a high false positive rate and a low threshold.
What is Western blot assay for HIV used for?
Rule in test - Specific, low false-positive rate, and high threshold.
What is viral load used for?
Monitor effect of drug therapy. High viral load associated with poor prognosis.
What is the cutoff for immuncompromised, and for AIDS?
Immunocomp: CD4+ < 400
CD4+ < 200, CD4+ % <14, or HIV+ with AIDS-defining illness eg Pneuomocystis
When may ELISA/Western blot be falsely negative?
First 1-2 months of infection.
When may ELISA/Western blot be falsely negative?
Babies born to infected mothers; anti-gp120 crosses the plasma.
What is the presentation of candida albicans in HIV+ with CD4 <500?
Oral thrush
What are the associated findings of candida in HIV+?
Scrapable white plaque, pseudohyphae on microscopy
What the presentation of EBV in HIV+ < 500?
Oral hairy leukoplakia
What are the associated findings of EBV in HIV+ < 500?
Unscrapable white plaque on lateral tongue
What the presentation of Bartonella in HIV+ < 500?
Bacillary angiomatosis
What are the associated findings of Bartonella in HIV+ < 500?
Biopsy with neutrophilic inflammation
What the presentation of HHV-8 in HIV+ < 500?
Kaposi Sarcoma
What are the associated findings of HHV-8 in HIV+ < 500?
Biopsy with neutrophilic inflammation - spindle cells
What the presentation of Cryptosporidum spp in HIV+ < 500?
Chronic, watery diarrhea
What are the associated findings of Cryptosporidum spp in HIV+ < 500 ?
Acid-fast oocysts in stool
What the presentation of HPV in HIV+ < 500?
Squamous cell carcinoma, commonly of anus
(men who have sex with men) or cervix
(women)
What the presentation of toxoplasma gondii in HIV+ < 200?
Brain abscesses - multiple ring enhancing lesions on MRI
What is the presentation of HIV itself with CD <200?
Dementia (ok?)
What is the presentation of JC virus reactivation with CD <200?
progressive multifocal leukoencephalopathy
What are the associated findings of JC virus reactivation with CD <200?
Non-enhancing areas of demyelination
What is the presentation of Pneumocystis jirovecci CD <200?
Ground glass opacities on CXR
What is the presentation of Aspergillus with CD <100?
Hemoptysis, pleruritic pain - cavitation or infiltrates on chest imaging
What is the presentation of Cryptococcus with CD <100?
Meningitis
What are the associated findings of Cryptococcus with CD <100?
Thickly encapsulated/budding years on India ink stain
What is the presentation of Candida with CD <100?
Esophagitis - white plaques on endoscopy, yeast and pseudohyphae on biopsy
What is the presentation of CMV with CD < 100?
Retinitis Esophagitis Colitis Pnuemonitis Encephalitis
What are the associated findings of CMV with CD < 100?
retinitis - cotton wool spots/extensive hemorrhage
esophagitis - linear ulcers
bx - cells w/ intranuclear (owl eye) inclusions
What is the presentation of EBV with CD < 100?
B-cell lymphoma - Non-Hodgkin, CNS lymphoma
What are the associated findings of EBV with CD < 100?
CNS lymphoma - ring enhancing, may be solitary (vs toxo)
What is the presentation of Histoplasma capsulatum with CD < 100?
Fever, weight loss, fatigue, cough, dyspnea, nausea, vomiting, diarrhea
What are the associated findings of Histoplasma capsulatum with CD < 100?
Oval yeast cells within macrophages
What is the presentation of Mycobacterium avium-intracellluare with CD < 100?
Non-specific systemic symptoms - fever, night sweats, weight loss, or focal lymphadenitis