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
