Background The reliable diagnosis of human T-cell leukemia virus type 1 (HTLV-1) infection is important, particularly as it can be vertically transmitted by breast feeding mothers to their infants. However, current diagnosis in Japan requires a confirmatory western blot (WB) test after screening/primary testing for HTLV-1 antibodies, but this test often gives indeterminate results. Thus, this collaborative study evaluated the reliability of diagnostic assays for HTLV-1 infection, including a WB-based one, along with line immunoassay (LIA) as an alternative to WB for confirmatory testing. Results Using peripheral blood samples from blood donors and pregnant women previously serologically screened and subjected to WB analysis, we analyzed the performances of 10 HTLV-1 antibody assay kits commercially available in Japan. No marked differences in the performances of eight of the screening kits were apparent. However, LIA determined most of the WB-indeterminate samples to be conclusively positive or negative (an 88.0% detection rate). When we also compared the sensitivity to HTLV-1 envelope gp21 with that of other antigens by LIA, the sensitivity to gp21 was the strongest. When we also compared the sensitivity to envelope gp46 by LIA with that of WB, LIA showed stronger sensitivity to gp46 than WB did. These findings indicate that LIA is an alternative confirmatory test to WB analysis without gp21. Therefore, we established a novel diagnostic test algorithm for HTLV-1 infection in Japan, including both the performance of a confirmatory test where LIA replaced WB on primary test-reactive samples and an additional decision based on a standardized nucleic acid detection step (polymerase chain reaction, PCR) on the confirmatory test-indeterminate samples. The final assessment of the clinical usefulness of this algorithm involved performing WB analysis, LIA, and/or PCR in parallel for confirmatory testing of known reactive samples serologically screened at clinical laboratories. Consequently, LIA followed by PCR (LIA/PCR), but neither WB/PCR nor PCR/LIA, was found to be the most reliable diagnostic algorithm. Conclusions Because the above results show that our novel algorithm is clinically useful, we propose that it is recommended for solving the aforementioned WB-associated reliability issues and for providing a more rapid and precise diagnosis of HTLV-1 infection.

中文翻译：

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建立一种新的人类 T 细胞白血病病毒 1 型感染诊断测试算法，用线免疫测定代替蛋白质印迹：日本诊断测定性能评估的合作研究

背景 人类 T 细胞白血病病毒 1 型 (HTLV-1) 感染的可靠诊断很重要，特别是因为它可以通过母乳喂养的母亲垂直传播给婴儿。然而，日本目前的诊断需要在筛选/初步测试 HTLV-1 抗体后进行确认性蛋白质印迹 (WB) 测试，但该测试通常会给出不确定的结果。因此，这项合作研究评估了 HTLV-1 感染诊断分析的可靠性，包括基于 WB 的诊断分析，以及作为 WB 替代方法进行验证性测试的线性免疫分析 (LIA)。结果使用先前经过血清学筛查和WB分析的献血者和孕妇的外周血样本，我们分析了日本市售的10种HTLV-1抗体检测试剂盒的性能。八个筛选套件的性能没有明显差异。然而，LIA 将大多数 WB 不确定样本确定为最终阳性或阴性（检测率为 88.0%）。当我们还比较了 LIA 对 HTLV-1 包膜 gp21 的敏感性与其他抗原的敏感性时，对 gp21 的敏感性最强。当我们还将 LIA 对包络 gp46 的敏感性与 WB 的敏感性进行比较时，LIA 对 gp46 的敏感性高于 WB。这些发现表明 LIA 是没有 gp21 的 WB 分析的替代验证测试。因此，我们在日本建立了一种新的 HTLV-1 感染诊断测试算法，包括验证测试的执行，其中 LIA 取代了原始测试反应样本的 WB，以及基于对验证测试不确定样本的标准化核酸检测步骤（聚合酶链反应，PCR）的额外决定。该算法临床实用性的最终评估涉及并行执行 WB 分析、LIA 和/或 PCR，以对在临床实验室进行血清学筛选的已知反应性样本进行确认测试。因此，LIA 其次是 PCR (LIA/PCR)，但无论是 WB/PCR 还是 PCR/LIA，都被认为是最可靠的诊断算法。结论 因为上述结果表明我们的新算法在临床上是有用的，