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W5-1-Diagnostic-methods.-Constance-Delaugerre

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HIV Diagnosis
Constance Delaugerre
Virology department
Saint Louis Hospital
Paris Diderot University
Dynamic of Markers
Window period
Antibodies
Plasma RNA
Threshold
p24 Antigen
Exposition
Direct Tests
11-12
14-15
20-21
28-29
Time (days))
Plasma HIV RNA
p24 Ag
Antibody-based EIAs
Indirect Tests
2Constance Delaugerre, HIV Diagnosis
Antibody/Antigen-based EIAs
Western-Blot
Rapid tests
Screening tests (1) :
Enzyme Immunosorbent Assays (EIAs)
EIA or ELISA 4th generation for detecting HIV1 & HIV2
antibodies and p24 Ag of HIV1
HIV1/2
Peptides
3 Constance Delaugerre, HIV Diagnosis
p24
Antibodies
Screening tests (2) :
Rapid Tests
A = Affordable
S = Sensible
S = Specific
U = User-friendly
R = Robust and Rapid
E = Equipment-free
D= Deliverable
1st GeneraLon : Ab
2nd GeneraLon : Ab-Ag
4 Constance Delaugerre, HIV Diagnosis
Blood sample
Oral swab
Some of them validated
As Home Self Test
5-20 min
Confirmatory tests for HIV1 or HIV2
Lysis
+
Blot
From Cunningham et al 2009
5 Constance Delaugerre, HIV Diagnosis
Viral load assay (plasma HIV-1 RNA)
•
•
•
•
From 1 ml of plasma or plasma
pool
QuanLficaLon (or detecLon)
of viral genome by PCR assays
using primers targeLng viral
« conserved » regions
Very specific and earlier test
(adapted for primary infecLon
diagnosis)
Limits : viral diversity, fully
supplied lab, high cost
6 Constance Delaugerre, HIV Diagnosis
COBAS® AmpliPrep/COBAS®
TaqMan® HIV-1 (ROCHE)
Xpert® HIV-1 Qual
test (GenExpert)
Serological TesOng Strategy (Adults)
SCREENING TEST A
(EIA or RT)
highly sensiOve
REACTIVE
SCREENING TEST B
(EIA or RT)
REACTIVE
POS
WESTERN BLOT HIV1
higher specificity
INTEDERMINED
VIRAL LOAD or p24 Ag
WB HIV2
7 Constance Delaugerre, HIV Diagnosis
NEG
If no recent exposi6on
NEG
Diagnosis in infants
PMTCT*
Birth
4-6 weeks 10 weeks
18 months
EIAs or RT/WB
HIV DNA
and/or
POSITIVE
2 consecuOve
posiOve NAT#
HIV RNA
NEGATIVE
2 consecuOve negaOve NAT#
2-4 weeks aVer stopping PTMTC
or aVer stopping breasWeeding
* Preven6on of mother-to-child transmission, # Nucleic Acid Tes6ng
8 Constance Delaugerre, HIV Diagnosis
Take home messages
•
HIV diagnosis in adults is based on highly sensiLve screening
tests
•
•
•
•
•
AnLgen-AnLbody based EIAs idenLfy infected individuals
earlier in the course of disease (15 days)
AnLbody based-Rapid Tests should always be confirmed by
another screening test
Confirmatory tests (i.e. Western blot) are needed to confirm
the specificity of the anLbodies and to differenLate HIV1 and
HIV2
Plasma HIV RNA (or p24 but included in Ag-Ab EIAs tests) is
recommended in case of primary infecLon
HIV diagnosis in infant is based on the posiLvity of two
Nucleic Acid Tests (HIV-DNA in whole blood or -RNA in
plasma)
Constance Delaugerre - HIV W 5-1 HIV Diagnosis
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