An efficient method for simultaneously screening for HIV, syphilis, and HCV based on one dried blood spot sample.

Objective: The aim of this study was to optimize the parameters of a dried blood spot (DBS)-based ELISA method to simultaneously screen for anti-HIV, anti-hepatitis C virus (HCV) and anti-treponema pallidum (TP) antibodies, and investigate the assay performance.

Methods: Experiments were performed to establish optimized parameters for a DBS-based ELISA method to simultaneously screen for anti-HIV, anti-HCV, and anti-TP antibodies. Then, 429 paired plasma and DBS samples were collected to evaluate the performance of the assay with optimized parameters. Plasma test results were used as the reference standard.

Results: The optimized assay conditions were: blood volume, 70-100 μL; DBS size, whole spot; eluent volume, 500 μL; eluent, PBS with 1‰ Tween20; elution time, 4 h; elution temperature, room temperature. The overall prevalence of HIV, HCV, and TP was 6.06% (95% confidence interval [CI]: 4.07-8.87%), 27.74% (95% CI: 23.60-32.28%), and 14.92% (95% CI: 11.75-18.73%). The clinical sensitivity of the assay for anti-HIV, anti-HCV, and anti-TP antibodies was 88.46%, 98.32%, and 92.19%, respectively. The assay was 100% specificity for each analyte. The assay positive predictive value for each analyte was 100%, and the negative predictive values were >98%. Of the 429 samples, 9 DBS results were different than the plasma results; in these samples the plasma signal-to-cutoff rations were low (range, 1.40-7.81).

Conclusion: The DBS-based ELISA method demonstrated good performance for simultaneously screening for anti-HIV, anti-HCV, and anti-TP antibodies. DBS samples are a promising method to screen for HIV, HCV, and TP infections.

Importance: DBS samples are a promising alternative to plasma samples, with the advantages of good sample stability, smaller blood volume, simpler storage, and easier transport. DBS sample testing is used for the diagnosis of a wide variety of pathogens, including HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV). The performance of DBS samples for the serological diagnosis of HIV, HCV, and Treponema pallidum (TP) has been demonstrated to be good in many studies, and therefore DBS is regarded as an ideal choice to screen for HIV, HCV, and TP infections, especially in difficult-access or resource-limited settings. There is no generally accepted procedure for sample collection and processing of DBS samples and there are few studies on simultaneous detection of anti-HIV, anti-HCV and anti-TP using a single DBS.