Validation of mailed via postal service dried blood spot cards on commercially available HIV testing systems

Abstract

The demand for HIV testing using dried blood spots (DBS) has increased recently. However, DBS is not an approved sample for HIV testing in Japan. This study examined the validation of HIV testing with DBS, prepared at the laboratory or remotely and mailed via postal service to the laboratory. DBS were punched out from a 5.5 mm diameter circle on filter paper, then eluted with 600 μL of phosphate buffered saline overnight at 4℃, and analyzed by Lumipulse S HIVAg/Ab (LUM). The mean LUM count of DBS was 237.4-times diluted compared to titrated plasma. Repeated sample testing showed that although LUM count of DBS decreased slightly with increase in sample storage time (up to one month), it did not affect the result of HIV testing with DBS. Based on testing of 50 HIV+ confirmed cases and 50 HIV- persons, the estimated sensitivity was 98% (49/50) with a specificity of 100% when the cut-off value is 0.5. The single false negative case was a patient with undetectable viral load over the last 10 years, resulting in a decrease of antibody titer below the cut-off level. In conclusion, although DBS cannot completely replace plasma in HIV testing because the sensitivity was a little lower than that of plasma, it can be potentially useful for a screening test by self-finger-prick and postal service use. This will allow people to receive HIV testing without visiting public health centers.

Keywords: HIV; dried blood spot; postal service; self-finger-prick.

Figure 1.

Comparison of Lumipulse S HIVAg/Ab among 9 filter papers. Blood samples were obtained from 7 HIV+ donors, then whole blood was placed on nine filter papers using a pipette. Each DBS was punched, eluted with PBS, and analyzed by Lumipulse S HIVAg/Ab.

Figure 2.

Comparison of Lumipulse S HIVAg/Ab among different volumes of blood placed on the filter paper using a pipette. The blood samples were obtained from 7 HIV+ donors, then 1, 2, 4, 8, 10, and 20 μL of whole blood were placed on the filter papers using a pipette. Each DBS was punched, eluted with PBS, and analyzed by Lumipulse S HIVAg/Ab.

Figure 3.

Stability test of Lumipulse S HIV Ag/Ab with DBS samples. Blood samples were obtained from 5 HIV+ donors. Five DBS were prepared from each using whole blood. They were stored at room temperature and analyzed by Lumipulse S HIV Ag/Ab after 0, 6-16, 13-18, 21-30 and 28- 37 days.

Figure 4.

Specificity and sensitivity test of Lumipulse S HIVAg/Ab and HISCL™-5000 HIV Ag+Ab using DBS samples. The DBS samples were obtained from 50 HIV+ and 50 HIV- donors. (A) 100 DBS samples were analyzed by Lumipulse S HIVAg/Ab. Dotted line: cutoff value. (B) 50 DBS samples from HIV+ donors were analyzed by HISCL™-5000 HIV Ag+Ab. Dotted line: cutoff value.

Figure 5.

Correlation between duration of ART and (A) Lumipulse S HIVAg/Ab and (B) HISCL™-5000 HIV Ag+Ab using DBS samples. DBS samples were obtained from HIV+ patients on ART. (A) 36 DBS samples were analyzed by Lumipulse S HIVAg/Ab. (B) 36 DBS samples were analyzed by HISCL™-5000 HIV Ag+Ab.