Norhaida A, Suharni M, Liza Sharmini A T, Tuda J, Rahmah N
Institute for Research in Molecular Medicine, Universiti Sains Malaysia, 11800 Minden, Penang, Malaysia.
Ann Trop Med Parasitol. 2008 Mar;102(2):151-60. doi: 10.1179/136485908X252250.
Currently, the laboratory diagnosis of toxocariasis, caused by Toxocara canis or T. cati, mainly relies on serological tests. Unfortunately, however, the specificities of most of the commercial tests that are available for the serodiagnosis of this disease are not very high and this may cause problems, especially in tropical countries where co-infections with other helminths are common. In an effort to develop a serological assay with improved specificity for the detection of Toxocara infection, an IgG(4)-ELISA based on a recombinant version (rTES-30USM) of the 30-kDa Toxocara excretory-secretory antigen (TES-30) has recently been developed. To produce the antigen, the TES-30 gene was cloned via assembly PCR, subcloned into a His-tagged prokaryotic expression vector, and purified by affinity chromatography using Ni(2+)-nitrilotriacetic-acid (Ni-NTA) resin. The performance of the ELISA based on the recombinant antigen was then compared with that of commercial kit, based on an IgG-ELISA, for the serodiagnosis of toxocariasis (Toxocara IgG-ELISA; Cypress Diagnostics, Langdorp, Belgium). Both assays were used to test 338 serum samples, including 26 samples from probable cases of toxocariasis. Assuming that all the probable cases were true cases, the assay based on rTES-30USM demonstrated a sensitivity of 92.3% (24/26) and a specificity of 89.6% (103/115) whereas the commercial kit exhibited a sensitivity of 100% (26/26) but a specificity of only 55.7% (64/115). The high sensitivity and specificity exhibited by the new IgG(4)-ELISA should make the assay a good choice for use in tropical countries and any other area where potentially cross-reactive helminthic infections are common.
目前，由犬弓首蛔虫或猫弓首蛔虫引起的弓首蛔虫病的实验室诊断主要依靠血清学检测。然而，不幸的是，大多数可用于该疾病血清诊断的商业检测的特异性并不高，这可能会导致问题，尤其是在热带国家，那里与其他蠕虫的共同感染很常见。为了开发一种对弓首蛔虫感染检测具有更高特异性的血清学检测方法，最近开发了一种基于30 kDa弓首蛔虫排泄分泌抗原（TES - 30）的重组版本（rTES - 30USM）的IgG(4)-ELISA。为了生产抗原，通过组装PCR克隆TES - 30基因，亚克隆到带有His标签的原核表达载体中，并使用Ni(2+)-次氮基三乙酸（Ni - NTA）树脂通过亲和层析进行纯化。然后将基于重组抗原的ELISA的性能与基于IgG-ELISA的商业试剂盒用于弓首蛔虫病血清诊断（弓首蛔虫IgG-ELISA；赛普拉斯诊断公司，比利时朗多普）的性能进行比较。两种检测方法都用于检测338份血清样本，包括26份来自可能的弓首蛔虫病病例的样本。假设所有可能的病例都是真正的病例，基于rTES - 30USM的检测方法显示出92.3%（24/26）的灵敏度和89.6%（103/115）的特异性，而商业试剂盒的灵敏度为100%（26/26），但特异性仅为55.7%（64/115）。新的IgG(4)-ELISA所表现出的高灵敏度和特异性应该使其成为热带国家以及任何其他潜在交叉反应性蠕虫感染常见地区的良好选择。
