HIV Presentation
List three classic features of acute HIV AND typical timing after exposure.
Fever, diffuse maculopapular rash, sore throat/lymphadenopathy, mucocutaneous ulcers.
~2–4 weeks after exposure.
Primary: ~ 3 weeks
Secondary: ~ 6-12 wks after initial symptom
Tertiary: Years to decades after initial infection (avg of 10-30 years)
Describe the main characteristics of HIV. Describe routes of transmission.
Key Points: + ssRNA, Enveloped, Diploid Genome
Transmission: Blood, bodily fluid, maternal-fetal (transplacental, intrapartum, postpartum)
Describe the main characteristics of Treponema pallidum. Transmission?
Gram-negative motile spirochete.
Sexual/direct contact, transplacental
HIV, AIDS, Syphilis, Chlamydia, Gonorrhea, Chancroid, and Hepatitis C
What determines the transition from chronic HIV to AIDS?
CD4 counts < 200 mm^3 (uL) OR develop an AIDS defining illness.
Describe the symptom(s) that characterize primary syphilis.
A chancre (painless ulcer at the site of invasion) and occasionally lymphadenopathy.
Name the three main genes that encode the major structural proteins, enzymes, and envelope glycoproteins of the virus.
Env, Gag, and Pol.
At what stages of syphilis are you most likely to be infectious?
Primary, secondary, and early latent.
What is the standard of care for those infected with HIV & Syphilis?
HIV: 2 NRTI's + integrase inhibitor / 2 NRTI's + boosted protease inhibitor
Syphilis: IM Penicillin G -> Oral Doxycycline
How can you differentiate acute HIV infection from EBV and CMV?
Rash (maculopapular) and laboratory testing (Monospot to rule out EBV and Ab testing)
Describe the three main symptoms that characterize secondary syphilis.
Rash (usually involving the palms and soles).
Condyloma lata (wart-like lesions, typically near the genitals)
Systemic symptoms (fever, sore throat, malaise)
What does it mean for HIV to be M (R5) or T (X4) tropic?
M-tropic (infect monocytes, macrophages, and T lymphocytes) bind CCR5 (R5), but not T cell lines
T-tropic variants use CXCR4 (X4) (T-cell lines and T-lymphocytes)
What population group has the highest occurrence of syphilis in the US?
MSM.
What is the disadvantage of oral-at-home testing compared to blood tests for HIV?
ONLY tests for HIV abs.
What are three AIDS-related symptoms directly caused by HIV?
HIV-associated dementia (HAD), neuropathy, and "AIDS wasting syndrome"
Describe the main symptom of both early and late congenital syphilis.
Early (>2 months old): Rash (palms and soles)
Late (>2 years old): Hutchinson teeth
What is the function of CCR5 and CXCR4? Role in HIV progression?
Chemokine receptors that direct T-cell migration.
CCR5 - (Mature) Chemotaxis to the site of inflammation
CXCR4 - (Naive) Chemotaxis to lymphoid tissues.
What factor(s) allow syphilis to evade the immune system?
Scarcity of antigenic outer membrane proteins & no LPS.
Why is it important to differentiate between HIV-1 and HIV-2?
HIV-2 has intrinsic resistance to NNTRI's & enfuvirtide (gp41 fusion inhibitor)
Name a classical OI associated with each CD count level.
CD4 < 500, 200, 100 mm^3
Oral Thrush (Candida)
Pneumocystis jirovecii pneumonia
Toxoplasma encephalitis
Describe the symptoms that characterize tertiary syphilis.
Gummas
Cardiovascular syphilis
Neurosyphilis
Name one accessory virulence factor that HIV uses. (Immunomodulatory)
Nef - Downregulates MHC I and CD4
Vif -Inhibits/degrades APOBEC3G (deaminates cytosines → uracils in the viral cDNA)
Vpu - Degrades tetherin (traps budding virions at the cell surface)
In what case would we see a negative VRDL/RPR with a positive FTA-ABS test?
VRDL/RPR - Testing for antibodies against lipid antigens (e.g. cardiolipin)
FTA-ABS - Direct treponemal ab test
Describe the diagnostic tests involved in diagnosing HIV & Syphilis.
HIV: Ag/Ab Testing (p24 antigen) -> HIV-1/2 Ab testing (->*) NAAT
Syphilis: Nontreponemal test -> Treponemal test.