33th Page Flashcards
What is the p24 antigen?
only present for a short time and disappears when antibodies to p24 appear.
How is p24 antigen detected?
Using a sandwich technique with anti-HIV-1 antibodies bound to a membrane, incubated with patient serum, followed by a second anti-HIV-1 antibody attached to an enzyme label.
What indicates a positive p24 antigen test?
confirmed by neutralization.
What is the neutralization assay process?
PRE-INCUBATE patient sample with anti-HIV
then RETEST to check for p24 presence in immune complexes that prevent binding to HIV antibodies on the membrane (Decrease absorbance)
Is p24 antigen detection recommended for routine screening?
NO
-Marc
When is p24 antigen detection most useful?
CSF
early infection suspected in seronegative patients, newborns
monitoring disease progress.
What is the indirect immunofluorescence assay used for?
It can be used to detect both virus and antibodies by testing patient serum against antigen applied to a slide.
How does the polymerase chain reaction (PCR) work?
looks for HIV DNA in the WBC blood of a person using radioactive or biotinylated probes.
What is the best sample for PCR testing?
peripheral blood
What other specimens can be used for PCR testing?
CSF, saliva, cervical secretions, and material from tissue.
What are the steps in cell culture for HIV detection?
- Stimulate cell growth in culture.
- Amplify the number of cells releasing the virus.
- Incubate cultures for one month.
- Confirm infection by detecting reverse transcriptase or p24 antigen in the supernatant.
What is the recommended timing for viral load monitoring?
2 measurements 2-3 weeks apart to determine baseline, and repeat every 3-6 months in conjunction with CD4 counts.
When should viral load be assessed after starting or changing antiretroviral therapy?
repeat 4-6 week
virus is detected by fixing patient cells to slide, incubating with anitbody
Indirect Immunofluorescence Assay
DNA is detected by using radioactive or biotinylated probes
PCR
