COMPARISON OF POOLED NAT VS' NEW HIV ANTIGEN TEST

1
DISCONTINUATION OR NO DISCONTIUNATIONCOMPARISON
OF SINGLE UNIT HIV ANTIGEN TESTING VS. POOLED NAT
TESTING
Gerald Schochetman, Ph.D. Abbott
Laboratories Diagnostics Division BPAC
Meeting September 14, 2000
2
OBJECTIVE
To develop more sensitive HIV antigen
assays Short term Comparable sensitivity to
pooled NAT testing Long term Sensitivity
equivalent to single unit NAT
testing
3
SENSITIVITY OF RESEARCH PRISM HIV Ag VS. CURRENT
HIV ANTIGEN ASSAY
ASSAY
p24 ANTIGEN
Copies/ml _at_ Dilution of
Estimated RNA
pg/ml (est.)
copies/ml
196
11200
4
4
Research PrismHIV Ag
1-2
1x10
-2x10
104-208
8-16
7x10
4
-1x10
5
58-83
HIVAG-1MC
7-10
729-1041
1 pg 1x104 copies/ml
4
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

5
EARLY SEROCONVERSION SAMPLES COMPARISON OF
POOLED NAT VS. HIV ANTIGEN TESTING
PANEL/BLEED
ABBOTT
Research
NAT (copies/ml)a
Copies/ml _at_ Dilution of
HIVAG-1MCa
PRISM AGc
Roche
NGI
bDNA
196
11200
S/COb
S/CO
SV-0251/D
0.34
3.05
16000
167
13
SV-0321/A
0.46
3.08
20000
208
17
PRB-941/3
0.55
2.32
50000
521
42
PRB-943/3
0.72
2.35
100000
1042
83
PRB-945/3
0.72
1.96
90000
20000
938/208
75/17
BCP-9013/6
0.47
1.98
56350
587
47
BCP-6240/7
0.53
1.98
11690
122
10
BCP-9016/9
0.72
2.06
69010
719
58
a Data obtained from panel information sheets b
S/CO gt 1.00 is reactive c Research data
6
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

7
CONCLUSIONS

• 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