William R. Oleszko, Ph.D.
Acting Associate Director, Public Health Laboratory
New York City Department of Health and Mental Hygiene
OBJECTIVE: To demonstrate the outcome of laboratory HIV antibody testing on specimens submitted to the NYC DOHMH’s PHL after implementation of the of HIV-1/2 Plus “O” combination screening EIA.
METHOD: In April of 2004, the PHL implemented BioRad’s HIV-1/2 Plus “O” EIA screening assay for all specimens submitted for HIV antibody analysis. During the last 9 months of 2004, approx. 74,000 specimens were submitted, assayed and HIV antibody reports transmitted to submitting health care providers. The PHL’s routine HIV antibody testing algorithm requires initial replicate screening followed by supplemental testing, if required. Specimens that are repeatedly nonreactive by the EIA screening assay are reported as “Negative for Antibody to HIV-1 and HIV-2”.
Specimens that are HIV-1/HIV-2 screening EIA repeat reactive are reflexed for HIV-1 Western Blot supplemental testing. The complete testing algorithm will be presented. The demonstration of discordant replicate HIV-1/HIV-2 EIA screening results (’splits’ or indeterminates/Ind) and discordant EIA (repeat reactive) and Western Blot (nonreactive) results (‘incompatibles’) require additional laboratory evaluation. The PHL has incorporated several supplemental assays and study protocol, including BioRad’s HIV-1 rLAV, HIV-2 EIA, Multispot HIV-1/HIV-2 Rapid EIA, V3 Peptide EIA and HIV DNA PCRs for HIV-1 and HIV-2 as a means of demonstrating whether actual or false reactivities to HIV are present in these specimens. Summaries will be presented.
RESULTS: An example of the April through December 2004 results for HIV-1/HIV-2 Plus ‘O’ “splits” and “incompatibles” are is shown in this table.

EIA ASSAY KIT HIV-1 rLAV Results HIV-1 Western Blot Results
Reactive ‘Splits’
Ind.		 Non-reactive Reactive Ind. . Non-reactive
HIV 1/2 Plus “O”
(N = 73,955)		 ‘Splits’
348 (0.47%)		 0 0 348 0 62 286
‘Incompatibles’
227 (0.31%)		 0 0 227 0 0 227

Of the 62 of the 348 initial HIV-1/HIV-2 Plus ‘O’ EIA screening “Split” that became HIV-1 Western Blot indeterminate (each with 1 to 2 nonconsensus bands), 60 were nonreactive by HIV-2 EIA, while 2 were repeatedly reactive by HIV-2 EIA. Of the 227 initial HIV-1/HIV-2 Plus ‘O’ EIA and HIV-1 Western Blot incompatible specimens all were nonreactive by both HIV-1 rLAV and Western blot, while only 3 had HIV-2 EIA reactivity, but were negative by HIV-1/2 MultiSpot, V3 peptide.
CONCLUSION: While no HIV antibody serologic assay is 100% sensitive and 100% specific, this laboratory’s experience in its initial implementation of BioRad’s HIV-1/HIV-2 Plus ’O’ EIA screening assay and the use of it’s HIV testing algorithm to resolve false reactive EIA screening results, ultimately resulted in a very low HIV antibody inconclusive rate.

Last Update: April 8, 2005