Burbelo Peter D, Ramanathan Roshan, Klion Amy D, Iadarola Michael J, Nutman Thomas B
Neurobiology and Pain Therapeutics Section, Laboratory of Sensory Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, 4 Center Drive, Bethesda, Maryland 20892, USA.
J Clin Microbiol. 2008 Jul;46(7):2298-304. doi: 10.1128/JCM.00490-08. Epub 2008 May 28.
The ability to diagnose Loa loa infection readily and accurately remains a demanding task. Among the available diagnostic methods, many are impractical for point-of-care field testing. To investigate whether luciferase immunoprecipitation systems (LIPS) can be used for rapid and specific diagnosis of L. loa infection, a LIPS assay was developed based on immunoglobulin G (IgG) and IgG4 subclass antibodies to a recombinant L. loa SXP-1 (designated LlSXP-1) antigen and tested with sera from healthy controls or patients with proven infection with L. loa, Mansonella perstans, Onchocerca volvulus, Strongyloides stercoralis, or Wuchereria bancrofti. A LIPS test measuring IgG antibody against LlSXP-1 readily differentiated L. loa-infected from uninfected patients and demonstrated markedly improved sensitivity and specificity compared with an LlSXP-1 IgG4-based enzyme-linked immunosorbent assay (67% sensitivity and 99% specificity). No significant immunoreactivity was observed with S. stercoralis-infected sera, but a small number of patients infected with O. volvulus, M. perstans, or W. bancrofti showed positive immunoreactivity. Measuring anti-IgG4-specific antibodies to LlSXP-1 showed a significant correlation (r approximately 0.85; P < 0.00001) with the anti-IgG results but showed no advantage over measuring the total IgG response alone. In contrast, a rapid LIPS format (called QLIPS) in which the tests are performed in less than 15 minutes under nonequilibrium conditions significantly improved the specificity for cross-reactive O. volvulus patient sera (100% sensitivity and 100% specificity). These results suggest that LIPS (and the even more rapid test QLIPS) represents a major advance in the ability to diagnose L. loa infection and may have future applications for point-of-care diagnostics.
随时准确诊断罗阿丝虫感染仍然是一项艰巨的任务。在现有的诊断方法中，许多方法对于即时现场检测并不实用。为了研究荧光素酶免疫沉淀系统（LIPS）是否可用于罗阿丝虫感染的快速特异性诊断，基于针对重组罗阿丝虫SXP-1（命名为LlSXP-1）抗原的免疫球蛋白G（IgG）和IgG4亚类抗体开发了一种LIPS检测方法，并使用来自健康对照或已证实感染罗阿丝虫、常现曼森线虫、盘尾丝虫、粪类圆线虫或班氏吴策线虫的患者的血清进行检测。一项检测针对LlSXP-1的IgG抗体的LIPS检测能够轻松区分感染罗阿丝虫的患者和未感染的患者，并且与基于LlSXP-1 IgG4的酶联免疫吸附测定相比，其灵敏度和特异性显著提高（灵敏度67%，特异性99%）。粪类圆线虫感染的血清未观察到明显的免疫反应性，但少数感染盘尾丝虫、常现曼森线虫或班氏吴策线虫的患者显示出阳性免疫反应性。检测针对LlSXP-1的抗IgG4特异性抗体与抗IgG结果显示出显著相关性（r约为0.85；P<0.00001），但与单独检测总IgG反应相比并无优势。相比之下一种快速LIPS形式（称为QLIPS），即在非平衡条件下不到15分钟即可完成检测，显著提高了对盘尾丝虫交叉反应患者血清的特异性（灵敏度100%，特异性100%）。这些结果表明，LIPS（以及更快的QLIPS检测）代表了罗阿丝虫感染诊断能力的重大进步，可能在即时诊断方面有未来应用前景。
