1. San Francisco Department of Public Health
Reactivity of an Array of HIV Antibody Assays with Specimens from Acutely Infected Individuals
Brian Louie, Jeffrey Klausner, Sally Liska, Teri Dowling and Mark Pandori
San Francisco Department of Public Health

2. Presentation Goals, Objectives
Describe how and why we use RNA detection to screen for HIV infection in San Francisco
Illustrate the ability of different antibody tests to detect infection in people presumed to be recently infected with HIV
Assess the sensitivities of all FDA-cleared HIV rapid antibody tests on acutely infected individuals

3. The 2006 Consensus Estimates: population size, HIV prevalence, and HIV incidence, San Francisco
*2 infants not included
Approximate overall prevalence in SF: %

4. The Diagnostic Window These values are estimates
For RNA, this assumes a test with 50 copy sensitivity

5. RNA Testing of Pooled Specimens

6. From Oct. 2003 to June 2007, using this RNA testing strategy:
42 specimens were found that were screened as antibody-negative, but contained HIV RNA; approx total tested over this time period
such specimens were deemed as recently infected (“acute” or “primary” HIV infection)
22 were screened by 1st generation EIA (Vironostika), 17 were screened by OraQuick rapid test (14 fingerstick, 3 oral), and 3 were screened with a 3rd generation EIA (Bio-Rad)

7. 22 of 42 were screened negative by 1st gen EIA (Vironostika)

8. 17 of 42 were screened negative by OraQuick Rapid test (14 fingerstick blood, 3 oral)
1 specimen
that was
missed by 1st
gen EIA was
pos by OQ

9. 3 of 42 were screened negative by 3rd gen EIA (Bio-Rad)
So… =
42 Total Specimens
That were
Antibody-screen
Negative,
But RNA +
14 of 42 were
positive by
This 3rd gen.
EIA test
and

10. Performance of Clearview Stat-pak with acute panel
1 of 42 was
Positive by
Stat-pak

11. Performance of Uni-gold (Trinity) with acute panel
11 of 42 were
positive by
Uni-gold

12. Performance of Multi-Spot (Bio-Rad) with acute panel
7 of 42 were
Positive by
Multi-spot

13. Performance of western blot with acute panel
zero of the panel of
42 were positive by
Western blot

14. Performance of all tests with follow-up specimens from acute panel; follow-up was days after initial screening test, median: 20 days

15. Summary of sensitivity of all tests on this acute panel
Follow-up specimens ( days,
median: 20 days after initial specimen)
Initial specimens:
1st gen. EIA: 0%
3rd gen. EIA: 33%
*Oraquick (p/s): 2.4%
*Stat-pak: 2.4%
Multi-spot: 17%
*Uni-gold: 26%
Western Blot: 0%
1st gen. EIA: 76%
3rd gen. EIA: 100%
*Oraquick (p/s): 87%
*Stat-pak: 97%
Multi-spot: 100%
*Uni-gold: 100%
Western Blot: 79%
* Low complexity, waived rapid tests

16. Observations:
All waived (low complexity) rapid tests are at least as sensitive as 1st generation EIA on acute specimens
One rapid test (Uni-gold) is notably more sensitive for acute infection than others
Western Blot seems unhelpful for confirming positive antibody screening tests from acutely infected individuals

17. Observations
Antibody “sandwich” technology based tests (3rd gen EIA and Uni-gold rapid) are more sensitive than other technologies for acutely infected individuals
IgM detection ?
They use higher volumes of specimen
A non-sandwich test which uses a high volume of specimen was next most sensitive rapid test (Multi-spot)

18. Discussion:
In certain high prevalence communities, the choice of which tests to use for screening must be made cautiously
RNA-based tests may be the only reliable confirmation test for Ab screens in high prevalence communities

19. Acknowledgments Ernest Wong, Senior Microbiologist, SFDPHL
Mahtab Shahkarami, Microbiologist, SFDPHL