Laboratory Diagnosis of HIV (Exam 3-5b) Flashcards
What is the structural gene called gag coding for?
core structural proteins - nucleocapsid and matrix
What is the structural gene env coding for?
glycoproteins that make up the envelope
What is the structural gene pol coding for?
enzymes for replication - in the core
What is gp41 referring to?
The transmembrane protein
What is gp120 referring to?
The docking protein
What is p24 referring to?
The capsid
What is p17 referring to?
The matrix protein
What coreceptors can HIV use to infect cells?
CCR5 or CXCR4
Which patients remain healthy for longer, patients with HIV that prefers R5 or X4?
Patients with HIV that prefers R5
What is the preferred receptor for M-trophic (R5) strains?
CCR5
What is the preferred receptor for T-trophic (X4) strains?
CXCR4
When are abs detectable in HIV patients?
3-12 weeks after primary infection
Which type of immune cell does HIV attack directly?
T helper cells
What are two other cellular/immunological effects of HIV?
Defective ag presentation (down-regulation of MHC I expression), and decrease in NK activity
What happens to CD4 T cells during the primary infection?
They decrease
What happens to CD4 T cells during the clinical latency phase?
They increase
What happens to CD4 T cells during AIDS?
They decrease
What are the characteristics of long-term nonprogressors (LTNP)?
Normal or mildly depressed CD4 T cells,
low viral loads,
asymptomatic for >10 years in absence of ART
What kind of test is done to look for p24?
ELISA (antibody+antigen)
What generation of testing is described below?
EIAs used antigen consisting of viral lysates to detect IgG antibodies. The window period = 56 days
First-generation
What generation of testing is described below?
Tests relied on recombination HIV proteins or synthetic peptides to detect HIV-1/2 IgG antibodies. Window period = 42 days
Second-generation
What generation of testing is described below?
Combination tests that can detect HIV-1 Groups M and O, as well as HIV-2. They also use recombinant/synthetic peptides to detect IgG antibodies, as well as IgM produced by B cells. Window period = 22 days
Third-generation
What generation of testing is described below?
Could detect HIV-1, Group M, and HIV-2 IgG and IgM, as well as the HIV-1 p24 antigen. Window period = 15 to 17 days
Fourth-generation
What generation of testing is described below?
A multiplexed screening that detecs and differentiates all three HIV analyte markers: HIV-1 Abs, HIV-2 Abs, and the HIV-1 p24 antigen
Fifth-generation
What indicateds a positive Western Blot test for HIV?
Bands for at least 2 of the 3 proteins: p24, gp41, and gp120/gp160
What are some of the limitations of Western Blot?
May misidentify HIV-2, less sensitive than newer screenings, frequently indeterminate, performed by ref labs (slow), labor intensive, technically difficult, and expensive
When does the p24 antigen become undetectable?
After host anti-p24 antibodies develop and viral load drops
What is the common test for DH to use to detect HIV?
Alere HIV Ab/Ag combo (rapid EIA)
In what order do HIV markers appear in an infetced person?
HIV RNA, p24 antigen, and then HIV-1/2 antibodies
Early infection, before seroconversion can lead to a false negative test. T or F?
True
Autoreactive antibodies can lead to a false positive test. T or F?
True
When is serological testing used for children to confirm diagnosis?
12 to 18 months of age
What is the preferring method for diagnosis of children?
Qualitative HIV-1 DNA PCR (detects proviral DNA)
Causative agent of syphilis?
gram-neg helically coiled spirochete bacteria - Treponema pallidum
Clinical manifestations of syphilis?
Localized skin infection, moves to organs, has latent stage, and can cause cardiac and neurological involvement
Transmission of syphilis?
Sexual, congenital (vertical), and parenteral (rarely)
Causative agent of lyme disease?
Borrelia burdorferi
Causative agent of relapsing fever?
Borrelia spp.
