HIV

Question 1

HIV

Answer 1

Retrovirus (RNA-dependent DNA polymerase makes DNA as a replicative intermediary)

Question 2

HIV characteristics

Answer 2

Virus binds to a specific receptor
Inserts viral genome into cell cytoplasm
Multiple steps in replicative process
Fusion of cells and loss of CD4 cells (helper T cells) results in immunodeficiency
Release of viral particles in productively infected cells
Integration of viral genome into resting cell genome

Question 3

Infection progression

Answer 3

Initial infection- retroviral syndrome with fevers and adenopathy (similar to mononucleosis-like illness)
Quiescent period where infected individual may be relatively asymptomatic
Decline in CD4 helper T cells resulting in susceptibility to opportunistic infections

Question 4

Characterization of status of HIV infection

Answer 4

Amt of virus present in serum (HIV RNA by PCR) and resistance pattern (20% of new infection occurs with resistant strains of HIV)
Degree to which immunosuppression has occurred
CD4 cell count
Coinfection status
-HPV
-Hep C
-Hep B
-TB
-VDs

Question 5

Presentation of HIV

Answer 5

Retroviral syndrome
Asymptomatic
-Screening: pretty much everyone of sexually active age should be tested by EIA
Illness caused by opportunistic infection
Kaposi sarcoma
B cell lymphoma

Question 6

Testing for HIV

Answer 6

HIV antibody testing
-2 enzyme-linked immunosorbent assay (ELIZA) tests FOLLOWED by Western blot analysis confirm HIV infection with a sensitivity >95%
HIV viral detection by PCR
CD4 marker measurement as a predictor of opportunistic infection risk

Question 7

HIV tx approaches

Answer 7

Stop replication of HIV

Prevention of acquisition of HIV

Question 8

HIV infection goals

Answer 8

Reduce HIV detection in serum to undetectable levels
Reduce risk of opportunistic infections when CD4 cell counts are low
Reduce transmission of HIV

Question 9

How HIV is spread

Answer 9

Sex-all kinds
Needles
Maternal/fetal
Not spread:
Kissing
Sharing meals
Sharing school facilities
Mosquitoes
Toilet seats
Govt conspiracies

Question 10

Phase I of HIV infection

Answer 10

Acute infection: lasting from infection until seroconversion
Usually lasts 3-8 wks
Virus replicates to high titer (usually of R5 type)
Concluded when Cytotoxic-T Lymphocytes develop, seroconversion occurs, and virus is diminished in the blood

Question 11

Phase II of HIV infection

Answer 11

Asymptomatic phase
Lasts for mos to .>15 mos
Continual virus replication
Active immune response and antigenic escape
Concluded by development of opportunistic infections

Question 12

Phase III of HIV infection

Answer 12

Host immune response collapses
Clinical progression to AIDS
Syncytium inducing (X4 viruses) are common

Question 13

Acute HIV-1 and seroconversion

Answer 13

> 50% of newly infected pts are asymptomatic
“Window period”- negative serology but high viremia
HIV test will be negative
Quantitative RNA by PCR will be very high

Question 14

Prophylaxis

Answer 14

PCP when CD4 <200 (trim/sulfa, dapsone, or pentamidine)
MTB when ppd >5mm
MAC when CD4 <50-150 (azithro, clarithro, rifabutin)
MAC and PCP prophylaxis may be stopped in antiretroviral therapy responders
Costly/controversial: CMV, fungal infections
PAP smears with aggressive f/u

Question 15

Fever: CD4 ~50-200

Answer 15

Bacterial pneumonia (>60% of hospital admissions for HIV-related fever) or pneumocystis (PCP)
Sinusitis

Question 16

Fever: CD4 <50 (1)

Answer 16

M. avium complex (MAC)-wgt loss, anemia, organomegaly, GI complaints, increased alkaline phosphatase
Fungal- crypto, histo, cocci peniciliosis (skin lesions)

Question 17

Fever: CD4 <50 (2)

Answer 17

Pneumocystis (PCP)
Bacterial pneumonia
Sinusitis
Line sepsis
CMV syndromes
Neoplastic, esp. lymphoma
Drug fever

Question 18

Bacterial pneumonia

Answer 18

Often lobar

Occasional Pseudomonas, Staph aureus

Question 19

Pneumocystis, carinii or jiroveci (PCP)

Answer 19

Often diffuse reticulonodular, abut can be lobar, mass-like, cavitary, or nl CXR
Subacute onset, nonproductive paroxysmal cough, gradual onset of sx
Trim/sulfa first choice; add steroids if severely hypoxemic- if early dx

Question 20

TB

Answer 20

When CD4 count high, usual apical cavitary dz with +PPD
In advanced AIDS, atypical presentations (diffuse penumonitis or nl CXR) and/or extrapulmonary dz common
MAC does not commonly cause pulmonary dz in AIDS

Question 21

Mucosal clues

Answer 21

Painful oral aphthous ulcers
Oral hairy leukoplakia- EBV causes gelatinous patches on lateral tongue
Severe, drug-resistant oral, genital, or perirectal HSV vesicles/erosions/ulcers
Look for Kaposi’s sarcoma on hard palate

Question 22

Brain mass

Answer 22

Ring-enhancing brain mass= toxoplalsmosis (esp basal ganglia) vs CNS B cell lymphoma (esp periventricular)