Amyloid beta peptides (Aβ1-42) have been found to be associated with the cause of Alzheimer’s disease (AD) and dementia. Currently, methods for detecting Aβ1-42 are complicated and expensive. The present study is aimed at developing an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) to detect Aβ1-42 by using a polyclonal antibody from alpaca, an application used in urine samples. The serum was collected from the alpaca after immunizing it with Aβ1-42 at 500 μg/injection 5 times. The ic-ELISA was developed and showed a half-maximal inhibitory concentration () of 103.20 ng/ml. The limit of detection (LOD) was 0.39 ng/100 μl. The cross-reactivity was tested with Aβ1-40 and 8 synthesized peptides that had sequence similarities to parts of Aβ1-42. The cross-reactivity of Aβ1-40 and peptide 1 (DAEFRHDSGYE) was 55% and 69.4%, respectively. The ic-ELISA was applied to analyze Aβ1-42 in the urine and precipitated protein urine samples. This method can be used for detecting a normal level of total soluble Aβ (approximately 1 ng in 5 mg of precipitated urine protein) and can be used for detecting the early stages of AD. It is considered to be an easy and inexpensive method for monitoring and diagnosing AD.

中文翻译：

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β-淀粉样蛋白 1-42 免疫分析方法的开发及其在尿液样本中的应用


β 淀粉样肽 (A β 1-42) 被发现与阿尔茨海默病 (AD) 和痴呆症的病因有关。目前，检测Aβ1-42的方法复杂且昂贵。本研究旨在开发一种间接竞争性酶联免疫吸附测定 (ic-ELISA)，通过使用羊驼毛多克隆抗体来检测 A β 1-42，这是一种用于尿液样本的应用。用Aβ1-42以500μg /注射免疫羊驼5次后收集血清。开发了 ic-ELISA，并显示了半最大抑制浓度（ ）为 103.20 纳克/毫升。检测限 (LOD) 为 0.39 ng/100 μl 。使用 A β 1-40 和 8 种与 A β 1-42 部分具有序列相似性的合成肽测试了交叉反应性。 A β 1-40 和肽 1 (DAEFRHDSGYE) 的交叉反应性分别为 55% 和 69.4%。应用ic-ELISA分析尿液和沉淀蛋白尿样中的Aβ1-42 。该方法可用于检测正常水平的总可溶性Aβ （5毫克沉淀尿蛋白中约1纳克），并可用于检测AD的早期阶段。它被认为是一种简单且廉价的 AD 监测和诊断方法。