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E992750C 1
Replacement of HIV-1 p24 Antigen Replacement of HIV-1 p24 Antigen Screening with HIV-1 RNA Nucleic Acid Screening with HIV-1 RNA Nucleic Acid
Testing (NAT) for Whole Blood DonationsTesting (NAT) for Whole Blood Donations
Since the implementation of p24 HIV-1 antigen Since the implementation of p24 HIV-1 antigen (Ag) screening in March, 1996, only 5 Ag positive (Ag) screening in March, 1996, only 5 Ag positive window-case donations have been identifiedwindow-case donations have been identified
Due to low Ag yield and the improved sensitivity Due to low Ag yield and the improved sensitivity of NAT screening for HIV-1, replacement of Ag of NAT screening for HIV-1, replacement of Ag with HIV-1 NAT should be possiblewith HIV-1 NAT should be possible
During 2 years of testing 14 million donations (ARC), During 2 years of testing 14 million donations (ARC), 136 samples were HIV-1 p24 Ag confirmed positive136 samples were HIV-1 p24 Ag confirmed positive 58 were false positive (based on RNA negativity, 58 were false positive (based on RNA negativity,
lack of seroconversion, and nonreproducible Ag lack of seroconversion, and nonreproducible Ag neutralization) = 1:241,379neutralization) = 1:241,379
74 were HIV Ab positive74 were HIV Ab positive 4 were recently infected seroconverting donors4 were recently infected seroconverting donors As of November 1999, 5 seroconverting donors As of November 1999, 5 seroconverting donors
identified in 23 million donationsidentified in 23 million donations– 1:4.6 million (ARC)1:4.6 million (ARC)– 1:9.2 million (US)1:9.2 million (US)
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Samples for TestingSamples for Testing
p24 Ag and HIV NAT reactive yield samples (N=4)p24 Ag and HIV NAT reactive yield samples (N=4)– Tested undiluted and diluted 1:128 in RNA-negative Tested undiluted and diluted 1:128 in RNA-negative
defibrinated plasmadefibrinated plasma
Commercial seroconversion samples (N=25)Commercial seroconversion samples (N=25)– Tested undiluted and diluted 1:128Tested undiluted and diluted 1:128
Diluted p24 Ag “External Control” sample that is Diluted p24 Ag “External Control” sample that is tested on all NAT runs (N=437)tested on all NAT runs (N=437)– 3 Ag+/Ab– units (S/CO 1-2 Coulter) pooled3 Ag+/Ab– units (S/CO 1-2 Coulter) pooled
– Pool diluted 1:16Pool diluted 1:16
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Comparison of HIV-1 p24 Ag Positive Comparison of HIV-1 p24 Ag Positive Window-Case U.S. Blood DonorsWindow-Case U.S. Blood Donors
11 IndexIndex 6 x 106 x 1055** 14.0*14.0* 9595 0.10.11212 3 x 103 x 1044 1.21.2 9595 2.32.3 POS – minus p31POS – minus p312222 1 x 101 x 1055 0.30.3 5.65.6 POS – all bandsPOS – all bands
22 IndexIndex 2 x 102 x 1066** 28.5*28.5* 9494 0.80.82020 1 x 101 x 1055 0.70.7 1.61.6 POS – minus p17, p31POS – minus p17, p314343 1 x 101 x 1044 0.10.1 5.35.3 POS – all bandsPOS – all bands
33 IndexIndex 1 x 101 x 1055 8.18.1 9595 0.10.11313 5 x 105 x 1055** 26.5*26.5* 9090 8.88.8 POS – minus p31 POS – minus p31
44 IndexIndex 1 x 101 x 1055 2.42.4 9595 0.00.01313 1 x 101 x 1066** 17.5*17.5* 8989 2.72.7 IND – p66IND – p667575 5 x 105 x 1044 0.10.1 17.417.4 POS – all bandsPOS – all bands
55 IndexIndex 3 x 103 x 1055 18.6*18.6* 9999 0.30.31010 4 x 104 x 1055** 0.20.2 4.34.3 POS – minus p31POS – minus p311717 1 x 101 x 1055 0.90.9 12.512.5 POS – minus p31POS – minus p312424 3 x 103 x 1044 0.70.7 8.58.5 POS – minus p31POS – minus p313131 2 x 102 x 1044 0.10.1 13.113.1 POS – minus p31POS – minus p31
SCSC
Sample Sample CollectionCollection
(days)(days) WBWBRNA RNA
Copies/mLCopies/mLp24 Ag p24 Ag S/COS/CO
PercentPercentNeut.Neut.
HIV-1/HIV-1/HIV-2 Ab HIV-2 Ab
S/COS/CO
E992750C 6
Detection of HIV-1 p24 Ag and NAT Yield Detection of HIV-1 p24 Ag and NAT Yield Samples by HIV-1 NAT (1:128 Dilution)Samples by HIV-1 NAT (1:128 Dilution)
High RNA titers (High RNA titers (101055 copies/mL) correspond copies/mL) correspond with p24 Ag positivitywith p24 Ag positivity
No p24 Ag reactive sample was found NAT No p24 Ag reactive sample was found NAT nonreactive even using a pool size of 128nonreactive even using a pool size of 128
NAT, even using pools of 128, is more sensitive NAT, even using pools of 128, is more sensitive than screening with the currently licensed tests than screening with the currently licensed tests for HIV-1 p24 Ag. According to these data, the for HIV-1 p24 Ag. According to these data, the Ag test could be replaced by the use of licensed Ag test could be replaced by the use of licensed pooled NATpooled NAT
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1
2
3
4
5
6
7
8Lo
g R
NA
Lev
el [
copi
es/m
L]
-2 -1.5 -1 -.5 0 .5 1 1.5 2
Log p24 S/CO
N = 146R2 = 0.78
Linear Relationship Between HIV RNA Linear Relationship Between HIV RNA Levels and p24 S/CO RatiosLevels and p24 S/CO Ratios
4.03 log (596-190,108 copies/mL) = 1
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-2
-1
0
1
2
3
4
5
6
7
8
9Lo
g H
IV R
NA
Lev
el [
copi
es/m
L]
-2 -1.5 -1 -.5 0 .5 1 1.5 2Log p24 S/CO
N = 146
95% Prediction Limits for Relationship of 95% Prediction Limits for Relationship of HIV RNA Levels and p24 S/CO RatiosHIV RNA Levels and p24 S/CO Ratios
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1
2
3
4
5
6
7
8Lo
g H
IV R
NA
Lev
el [
copi
es/m
L]
RNA Only (N=61) p24 Pos (N=85)
P = <0.0001*
* Mann-Whitney Test
HIV-1 RNA Levels During “RNA Only” HIV-1 RNA Levels During “RNA Only” and “p24 Positive” Window Periodsand “p24 Positive” Window Periods
E992750C 22
1
2
3
4
5
6
7
8Lo
g R
NA
Lev
el [
copi
es/m
L]
-2 -1.5 -1 -.5 0 .5 1 1.5 2
Log p24 S/CO
Linear Relationship Between HIV-1 RNA Levels Linear Relationship Between HIV-1 RNA Levels and p24 S/CO Ratios in 32 Casesand p24 S/CO Ratios in 32 Cases