Poster #990
Contact Information:
Joanne Stekler, MD, MPH
Box 359931, Harborview Medical Center
325 Ninth Avenue, Seattle, WA 98104
Phone: (206) 731-8312, Fax: (206) 731-5109
Email: jstekler@u.washington.edu
Limitations of HIV Antibody Testing in a Population with High Incidence of HIV Infection
Joanne Stekler1,2, Paul D. Swenson1,2, Robert W. Coombs1, Joan Dragavon1, Catherine A. Brennan3, Sushil G. Devare3, Ana Vallari3, Priscilla Swanson3,
Robert W. Wood1,2, Matthew R. Golden1,2
ABSTRACT
Background
The Centers for Disease Control and Prevention recently recommended expanding HIV antibody testing. However, HIV nucleic acid
amplification tests (NAAT) are more sensitive than antibody tests in acute and early infection, when persons are highly infectious.
Methods
From 9/03-6/08, Public Health-Seattle & King County offered HIV antibody testing to men who have sex with men (MSM) using the
OraQuick Advance Rapid HIV-1/2 Antibody Test (OraSure) on oral fluid or finger-stick blood specimens or using an enzyme
immunoassay (EIA) [Vironostika HIV-1 Microelisa System (bioMerieux) or Genetic Systems rLAV EIA (Bio-Rad)]. An EIA was used to
confirm reactive rapid tests and to screen specimens from OraQuick-negative MSM prior to pooling for HIV NAAT.
We used frozen sera from 16 EIA-negative/NAAT-positive MSM to evaluate the ability of the 4th generation ARCHITECT HIV Ag/Ab
Combo assay (Abbott Diagnostics, not available for sale in the US) to detect acute infection. HIV RNA levels were quantified using the
Abbott RealTime HIV-1 assay.
Results
Overall, 328 (2.3%) of 14,005 specimens were HIV EIA-positive, and 36 (0.3%) EIA-negative MSM tested NAAT-positive. Among the
6811 OraQuick-negative specimens, 16 (0.2%) HIV-infected MSM were EIA-reactive, and 23 (0.3%) EIA-negative MSM were diagnosed
with acute HIV infection through pooled HIV NAAT. 14 of the 16 OraQuick-negative/EIA-reactive testers had positive Western Blot
results, and most had evidence of early HIV infection. Among rapid testers, OraQuick detected only 153 (80%) of 192 HIV-infected
MSM, and OraQuick plus an EIA detected 169 (88%) infections detected by the program.
The ARCHITECT HIV Ag/Ab Combo assay detected 15 (94%) of 16 MSM with acute HIV infection who had a median HIV RNA level
of 6.6 (IQR 5.8-6.9) log10 copies/mL. The specimen with the non-reactive test had an HIV RNA level of 4.2 and 3.7 log10 copies/mL by
the real-time RT-PCR and Abbott RealTime HIV-1 assays, respectively.
Conclusions
1) OraQuick performed on oral fluids or finger-stick blood specimens may be less sensitive than early generation EIAs.
2) Our findings may not be generalizable to populations with lower HIV prevalence and incidence.
3) HIV NAAT should be integrated into HIV testing programs serving MSM and other high-incidence populations with frequent HIV
testing, particularly when rapid antibody testing is employed.
4) 4th generation antigen-antibody combination assays may be a reasonably sensitive alternative to HIV NAAT.
2Public
of Washington, Seattle, WA, USA
METHODS (continued)
Laboratory testing
● HIV antibody testing by:
- 1st generation Vironostika HIV-1 Microelisa System (2003-2006)
- 2nd generation Genetic Systems rLAV EIA (2006-2008)
● Rapid HIV testing by OraQuick Advance Rapid HIV-1/2 Antibody Test
Offered to: high risk MSM at PHSKC STD Clinic, all MSM at Gay City/bathhouses
Both oral fluid testing and fingerstick whole blood
● Pooled HIV NAAT by Procleix HIV-1 Discriminatory Assay (2003-2005) and independentlyvalidated, quantitative real-time RT-PCR amplification assay (TaqMan, 2005-2008).
Pooling algorithm: 30 MSM → 3 intermediate pools → 1 master pool
2003-2005
Negative
EIA
HIV NAAT
Negative
rapid test
2005-2008
Negative
EIA
BACKGROUND
Negative
rapid test
● Recent Centers for Disease Control and Prevention recommendations aim to identify the
estimated 21% of HIV-infected persons unaware of their HIV status.
● HIV antibody tests, antigen-antibody combination assays, and HIV nucleic acid amplification
testing (HIV NAAT) have different abilities to detect HIV persons in the period after HIV
acquisition.
EIA
HIV NAAT
RESULTS
STANDARD ANTIBODY TESTING
N=7041
Study Population
● MSM tested for HIV through PHSKC:
1) PHSKC Sexually Transmitted Diseases (STD) Clinic (~3500 tests/yr)
#HIV positive
Cumulative # HIV positive
Cumulative sensitivity
EIA
159 (2.0%)
159
92%
HIV NAAT
13 (0.2%)
172
99%1
2) Gay City Health Project Wellness Center (~1800 tests/yr)
3) Seattle bathhouses (3 sites, ~400 tests/yr)
Frequency of testing among persons with
recent HIV infection changes test sensitivity
OraQuick-negative/EIA-positive test results
Bands Present on Western Blot
ID
specimen EIA
WB
Result
p18
p24
p32
gp41
p51
p55
p65
gp120
gp160
Last negative
HIV test (days)
1
FS
1st
+
+
+
+
39
2
OF
1st
+
+
+
+
374a
3
FS
2nd
+
+
+
+
516
4
FS
2nd
+
+
+
+
+
324
nd
5
OF
2
+
+
+
+
161a
6
FS
2nd
Ind
+
+b
290
7
OF
2nd
+
+
+
78c
8
FS
2nd
+
+
+
+
559
9
OF
2nd
+
+
+
+
+
345
nd
10
OF
2
+
+
+
NA
nd
11
OF
2
+
+
+
+
+
+
+
+
1209
12
FS
2nd
+
+
+
+
+
+
+
201
13
OF
2nd
Ind
+
NAd
14
FS
2nd
+
+
+
+
+
251
nd
15
OF
2
+
+
+
+
+
98
nd
16
OF
2
+
+
+
+
+
+
+
+
+
387e
WB: Western Blot; OF: oral fluids; FS: fingerstick; Ind: Indeterminate; NA: not available.
aIDs #2 and #5 reported seroconversion symptoms 23 and 42 days prior to testing, respectively.
bFaint gp160.
cID #7 had a positive EIA and WB six days prior to his false-negative rapid test result through PHSKC.
eID #13 had a CD4 count of 4 cells/mm3, no Western Blot evolution, and was likely OQ-negative due to late stage HIV/AIDS and seroreversion
eID #16 had a positive FS OraQuick one day prior to his false-negative rapid test result through PHSKC.
Acute HIV infection
(EIA-neg/RNA-pos)
Summary of confirmed HIV test results (9/03-6/08)
METHODS
Diagnostics, Abbott Park, IL, USA
Results of specimens tested by ARCHITECT® HIV Ag/Ab Combo
● Retrospective antibody testing
- 4th generation ARCHITECT® HIV Ag/Ab Combo
- Abbott RealTime HIV-1 assay quantified HIV RNA levels in stored serum
● Public Health – Seattle & King County (PHSKC) began a pooled HIV NAAT program in
2003, targeted to men who have sex with men (MSM).
3Abbott
Health - Seattle & King County, WA, USA
● HIV screening recommended quarterly for high risk MSM, annually for other MSM
RAPID ANTIBODY TESTING
N=6964
High risk MSM = report of unprotected anal intercourse with partners of unknown or discordant
serostatus, methamphetamine or popper use, or bacterial STD in last year.
OraQuick
153 (2.2%)
153
80%
EIA
16 (0.2%)
169
88%
Data collection and statistical analyses
HIV NAAT
23 (0.3%)
192
100%
● Electronic medical records and detailed chart review
1False-negative
● Program certified as exempt from informed consent requirements other than verbal consent
required for HIV testing.
● Median interval between testing and receipt of results was 19 (IQR 15-21) days for anonymous
testers and 16 (IQR 14-19) days for confidential testers (p=.2).
HIV NAAT result 4 days after exposure to partner with acute HIV infection
Possible early HIV infection
(EIA-positive/gp41-negative)
Established HIV infection
(gp41-positive)
S/COa: result
Log10copies/mL
S/COa: result
Log10copies/mL
S/COa: result
Log10copies/mL
EIA
Combo
TaqMan Abbott
EIA
Combo
Abbott
EIA
Combo
Abbott
b
c
1 0.4 : - 2.2: +
5.5
5.1
17
5.2: +
14.5: +
4.1
33 8.3: + 328.6: +
2.8
2 NA
2.7: +
5.6
5.4
18
3.4: +
10.0: +
<2.6
34 7.5: + 240.8: +
4.0
3 0.3b: - 9.8: +
>6
6.0
19c 4.3: +
58.5: +
<2.6
35 7.5: + 293.3: +
<2.6
4 NA
5.1: +
5.8
5.7
20c 6.6: +
51.0: +
4.4
36 7.3: + 301.8: +
<2.6
b
5 0.5 : - 108.9: +
>6
6.8
21
4.8: +
24.9: +
2.6
37 5.3: + 82.2: +
3.9
b
6 0.6 : - 101.6: +
>6
7.4
22
6.2: +
15.3: +
4.5
38 7.6: + 437.7: +
3.0
7 0.4b: - 463.4: +
>6
>8
23
5.6: +
27.1: +
2.9
39 6.4: + 57.4: +
3.9
8 0.08: - 21.3: +
5.6
6.2
24
5.2: +
23.5: +
4.2
40 7.2: + 251.4: +
<2.6
9 0.6: 36.4d: +
>6
6.6
25
3.2: +
9.0: +
4.7
41 6.8: + 174.2: +
<2.9
d
10 0.02: - 36.3 : +
>6
6.8
26
5.9: +
29.2: +
5.4
42 7.9: + 410.4: +
3.8
d
11 0.1: 42.8 : +
>6
6.8
27
6.0: +
16.5: +
3.7
43 7.9: + 399.2: +
<2.8
12 0.3: 45.9d: +
>6
6.6
28
5.8: +
35.9: +
4.5
44 8.1: + 200.3: +
4.1
13 0.2: 10.4: +
5.9
5.8
29
6.0: +
90.6: +
4.9
45 6.8: + 149.5: +
<2.9
14 0.2: 80.7: +
>6
7.3
30
5.9: +
36.2: +
4.6
46 8.3: + 339.9: +
3.5
15 0.2: 0.2: 4.2
3.7
31
6.6: +
94.6: +
5.5
47 7.6: + 276.4: +
4.1
16 0.1: 54.6: +
>6
6.9
32
3.3: +
100.7: +
<2.4
48 7.8: + 334.7: +
2.8
EIA: enzyme immunosorbent assay; NA: not available.
aA signal to cut-off (S/CO) ratio greater or equal to 1.0 was considered reactive.
bIDs #1, 3, and 5-7 were screened by the 1st generation EIA. All others were screened by the 2nd generation EIA.
cEarly infection IDs #17, 19, and 20 in this table are samples from IDs #4, 8, and 9, respectively, from OQ-neg/EIA-pos table.
dAcute infection IDs # 9-12 were previously tested using the Abbott HIVAB HIV-1/HIV-2 (rDNA) 3rd generation EIA, and all tested HIV-negative with S/CO
ratios of 0.18, 0.36, 0.13, and 0.18, respectively.
● All 16 specimens from HIV-uninfected individuals tested HIV-negative
● All specimens from EIA-positive individuals were HIV-reactive
● The
generation ARCHITECT HIV Ag/Ab Combo detected 15 (94%) of 16 EIA-negative/NAAT-positive MSM with
acute HIV infection and median HIV RNA of 6.6 (IQR 5.8-6.9) log10 copies/mL.
4th
1.0
0.9
0.8
0.7
0.6
test sensitivity
1University
0.5
0.4
0.3
HIV NAAT, window = 14 days
Antibody test, window = 35 days
0.2
0.1
0.0
0
30
60
90
180
270
360
test interval in days
● Assumptions:
- timing of testing is independent of the risk for HIV acquisition
- HIV antibody and NAAT detect all infections after the "window period“
● Annual testing by HIV antibody and NAAT detect 91% and 96% of infections
● Semi-annual testing intervals detect 84% and 93% of infections
● Quarterly testing intervals detect 72% and 86% of infections
● Increased testing frequency will increase frequency of false-negative HIV tests
LIMITATIONS
● Findings may not be generalizable to populations with lower HIV prevalence and
incidence.
CONCLUSIONS
1) OraQuick performed on oral fluids or finger-stick blood specimens may be less
sensitive than early generation EIAs.
2)
HIV NAAT should be integrated into HIV testing programs serving MSM and
other high-incidence populations with frequent HIV testing, particularly when
rapid antibody testing is employed.
3) 4th generation antigen-antibody combination assays may be a reasonably
sensitive alternative to HIV NAAT.
ACKNOWLEDGEMENTS
We would like to thank clients and providers at the Gay City Health Project Wellness Center, PHSKC
STD Clinic and other PHSKC testing sites as well as PHSKC for database management and data
support.