Department of Cell and Chemical Biology, Leiden University Medical Center, Leiden, Netherlands.
Department of Parasitology, Leiden University Medical Center, Leiden, Netherlands.
Front Immunol. 2018 Nov 14;9:2635. doi: 10.3389/fimmu.2018.02635. eCollection 2018.
Traditional microscopic examination of urine or stool for schistosome eggs lacks sensitivity compared to measurement of schistosome worm-derived circulating antigens in serum or urine. The ease and non-invasiveness of urine collection makes urine an ideal sample for schistosome antigen detection. In this study several user-friendly, lateral-flow (LF) based urine assays were evaluated against a composite reference that defined infection as detection of either eggs in urine or anodic antigen in serum. In a Tanzanian population with a prevalence of 40-50% ( prevalence <2%), clinical samples from 44 women aged 18 to 35 years were analyzed for infection. Urine and stool samples were examined microscopically for eggs, and serum samples were analyzed for the presence of the anodic antigen. Urines were further subjected to a set of LF assays detecting (circulating) anodic (CAA) and cathodic antigen (CCA) as well as antibodies against soluble egg antigens (SEA) and crude cercarial antigen preparation (SCAP). The urine LF anodic antigen assay utilizing luminescent upconverting reporter particles (UCP) confirmed its increased sensitivity when performed with larger sample volume. Qualitatively, the anodic antigen assay performed on 250 μL urine matched the performance of the standard anodic antigen assay performed on 20 μL serum. However, the ratio of anodic antigen levels in urine vs. serum of individual patients varied with absolute levels always higher in serum. The 10 μL urine UCP-LF cathodic antigen assay correlated with the commercially available urine POC-CCA (40 μL) test, while conferring better sensitivity with a quantitative result. Urinary antibodies against SEA and SCAP overlap and correlate with the presence of urinary egg and serum anodic antigen levels. The UCP-LF anodic antigen assay using 250 μL of urine is an expedient user-friendly assay and a suitable non-invasive alternative to serum-based antigen testing and urinary egg detection. Individual biological differences in the clearance process of the circulating antigens are thought to explain the observed high variation in the type and level of antigen (anodic or cathodic) measured in urine or serum. Simultaneous detection of anodic and cathodic antigen may be considered to further increase accuracy.
与血清或尿液中检测血吸虫虫源性循环抗原相比，传统的尿液或粪便显微镜检查血吸虫卵的灵敏度较低。尿液采集简便、无创，是检测血吸虫抗原的理想样本。本研究评估了几种用户友好型的侧向流动（LF）尿液检测方法，以复合参考标准为对照，该标准将感染定义为尿液中检测到虫卵或血清中检测到阳极抗原。在坦桑尼亚人群中，流行率为 40-50%（流行率<2%），对 44 名年龄在 18-35 岁的女性的临床样本进行了分析，以确定感染情况。对尿液和粪便样本进行显微镜检查以检测虫卵，对血清样本进行阳极抗原分析。尿液进一步进行了一组 LF 检测，检测（循环）阳极（CAA）和阴极抗原（CCA）以及针对可溶性卵抗原（SEA）和粗尾蚴抗原制剂（SCAP）的抗体。利用上转换报告粒子（UCP）的尿液 LF 阳极抗原检测在使用较大样本量时证实了其更高的灵敏度。定性地，使用 250 μL 尿液进行的阳极抗原检测与使用 20 μL 血清进行的标准阳极抗原检测性能相当。然而，个体患者尿液与血清中阳极抗原水平的比值随绝对水平而变化，血清中始终较高。10 μL 尿液 UCP-LF 阴极抗原检测与市售尿液 POCC-CA（40 μL）检测相关，同时具有定量结果和更好的灵敏度。针对 SEA 和 SCAP 的尿液抗体与尿液卵和血清阳极抗原水平的存在重叠且相关。使用 250 μL 尿液的 UCP-LF 阳极抗原检测是一种方便、用户友好的检测方法，是基于血清的抗原检测和尿液卵检测的合适替代方法。循环抗原清除过程中的个体生物学差异被认为解释了在尿液或血清中测量到的抗原（阳极或阴极）的类型和水平的高变异性。同时检测阳极和阴极抗原可能被认为可以进一步提高准确性。
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