Summary auto-generated
This study compared the Genie HIV-1/2 assay, a synthetic-peptide enzyme immunoassay, with Western blot for confirming HIV-1 antibodies in sera showing repeated positive results on initial screening. The researchers tested 137 sera from 13,405 patient samples screened in Saskatchewan during 1993, plus 50 known HIV-1 positive reference sera. Among the 137 EIA-positive sera, 33 were positive and 64 were negative in both assays. Critically, 36 sera were negative by Genie but indeterminate by Western blot, while 4 were indeterminate by Genie. All indeterminate results were confirmed as negative by reference laboratory testing. The Genie assay provided definitive results for 97% of EIA-positive sera compared to 71% for Western blot. The Genie test required only 15 minutes versus 4 hours for Western blot, yielded fewer indeterminate results (3% versus 28%), and demonstrated excellent overall concordance with reference testing. While Genie costs were slightly higher ($15 versus $10 per sample), the rapid turnaround, high accuracy, and minimal indeterminate results made it an attractive alternative to Western blot for HIV-1 antibody confirmation.
Key findings
- Genie assay provided definitive results for 97% of EIA-positive sera compared to 71% for Western blot
- Genie assay produced only 3% indeterminate results versus 28% for Western blot
- Genie assay completed in 15 minutes compared to 4 hours for Western blot
- All discordant and indeterminate results were confirmed negative by reference laboratory RIPA testing
- Genie assay demonstrated excellent concordance with Western blot and reference testing for true positive cases
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Abstract
The Genie HIV-1/2 kit (Sanofi Diagnostics Pasteur, Montreal, Quebec), a synthetic-peptide solid-phase enzyme immunoassay, was evaluated as a confirmatory assay for HIV-1 antibodies in comparison with Western blot (BioRad, Hercules, CA, USA) on 50 stored HIV-1 antibody-positive sera and the 137 sera yielding repeated positive results in the conventional EIA screen out of 13405 fresh patient sera from Saskatchewan in 1993. The stored HIV-1-positive sera were uniformly positive in the Genie test. Of the 137 EIA screen-positive sera, 33 were uniformly positive and 64 were uniformly negative in Genie and Western blot; 36 were Genie-negative and indeterminate by Western blot; and four were Genie indeterminate, of which one was negative and three were indeterminate by Western blot. All HIV-1 Western blot-indeterminate and Genie-interdeterminate sera were negative in radio-immunoprecipitation assay (RIPA) and Western blot for HIV-1 and HIV-2 antibodies performed by a reference laboratory. Genie gave an accurate definitive result for 97% of EIA positive sera compared with 71% for Western blot. There was excellent correlation between Genie, Western blot and RIPA results. However, the Genie assay was faster, less costly and yielded fewer indeterminate results than Western blot in confirmatory testing for HIV-1 antibodies.