Background: Less-sensitive (LS) HIV enzyme immunoassays (EIAs) can distinguish persons who have recent HIV infections from those who have long-standing HIV infection. The Vironostika-LS HIV-1 EIA uses serum samples to determine HIV incidence. Dried blood spots (DBS), which can be collected by finger stick instead of venous puncture, are easier than serum samples to collect, transport, and store. DBS are also stable for long-term storage. We have modified the Vironostika-LS HIV-1 EIA for use with DBS samples.

Methods: The Vironostika-LS HIV-1 EIA detects recent HIV seroconversion using the 2-step Serological Testing Algorithm for Recent HIV Seroconversion (STARHS). In this algorithm, blinded samples were first tested with a sensitive EIA, and EIA-positive specimens were confirmed by conventional Western blot methods. Positive specimens were tested with a less-sensitive EIA that determined whether the specimen represented a person with a recent or long-standing HIV infection. We applied the Vironostika-LS EIA to a blinded set of 217 HIV⁺ paired serum and DBS samples taken from young men who have sex with men (YMS). We also applied the test to a matching set of 61 serum and DBS samples from persons with AIDS. For this testing, serum-based calibration materials were used to calibrate the standardized optical density for both the serum samples and the DBS samples. To optimize the test for DBS, we have developed calibration and control materials in the filter paper matrix.

Results: In the YMS set, 95% of the paired serum/DBS samples had concordant results. The R² correlation between serum and DBS results was 0.85 (p < 0.0001). In the AIDS set, 100% of the paired serum/DBS samples had concordant results, but 8.19% of the samples gave non-reactive results. These 5 samples probably represent patients whose immune response is impaired to the point that their antibody levels are similar to early infections.

Conclusion: DBS can be used with the Vironostika-LS HIV-1 EIA to detect HIV incidence as part of STARHS. The increased ease of collection, transport, storage, and stability of DBS samples compared with serum samples will allow for more comprehensive testing of target populations.