DISCONTINUATION OR NO DISCONTIUNATION: COMPARISON OF SINGLE UNIT HIV ANTIGEN TESTING VS. POOLED NAT TESTING Gerald Schochetman, Ph.D. Abbott Laboratories Diagnostics Division BPAC Meeting September 14, 2000

To develop more sensitive HIV antigen assays Short term: Comparable sensitivity to pooled NAT testing Long term: Sensitivity equivalent to single unit NAT testing OBJECTIVE

SENSITIVITY OF RESEARCH PRISM HIV Ag VS. CURRENT HIV ANTIGEN ASSAY ASSAYp24 ANTIGEN Dilution of pg/ml (est.) Research PrismHIV Ag 1-2 Estimated RNA copies/ml 1x x10 4 1: : x x HIVAG-1MC pg = 1x10 4 copies/ml

Comparison Between Sensitive HIV Antigen Testing and NAT Sensitivity of antigen assay is ~1.0 pg or ~10,000 copies of viral RNA Even at a claimed 50 copies/ml sensitivity for NAT: - a sample must have at least 4800 copies of viral RNA/ml to be detected in a pool of 96, or - 60,000 copies of viral RNA/ml in a pool of 1200

PANEL/BLEED #ABBOTTResearchNAT (copies/ml) a Dilution of HIVAG-1MC a PRISM AG c RocheNGIbDNA1:961:1200 S/CO b S/CO SV-0251/D SV-0321/A PRB-941/ PRB-943/ PRB-945/ /20875/17 BCP-9013/ BCP-6240/ BCP-9016/ EARLY SEROCONVERSION SAMPLES: COMPARISON OF POOLED NAT VS. HIV ANTIGEN TESTING a Data obtained from panel information sheets b S/CO > 1.00 is reactive c Research data

Advantages of Individual HIV Antigen Testing vs Pooled NAT Testing Fully automated system for antigen testing Rapid test results Process controls for enhanced GMP compliance No sample preparation/contamination issues Ability to confirm using neutralization test Simplicity for implementation No pools to dilute sensitivity No dissection of pools No shipping of specimens

Gap between individual antigen testing using a sensitive assay for HIV antigen and NAT of pooled samples may not be significant As opposed to discontinuation: Manufacturers should be encouraged to develop ultra-sensitive HIV antigen assays with sensitivities equal to or greater than single unit NAT CONCLUSIONS