Section of Parasitology, Department of Zoology, Aligarh Muslim University, Aligarh, India.
Section of Parasitology, Department of Zoology, Aligarh Muslim University, Aligarh, India.
Acta Trop. 2020 May;205:105400. doi: 10.1016/j.actatropica.2020.105400. Epub 2020 Feb 17.
The foodborne trematodiases pose a significant health problem to the animals as well as the human population living in close proximities with the livestock and are still considered as the neglected tropical diseases by the World Health Organisation. The digenetic trematode, Gigantocotyle explanatum infecting the liver of Indian water buffalo, Bubalus bubalis, has been identified as one of the most common helminth parasite responsible for the disease, amphistomosis, in livestock. Despite huge abattoir prevalence, the epidemiological data and the actual economic losses incurred due to this parasite alone are yet to be established probably due to the limitations of routinely used diagnostic tests. The gold standard for the confirmation of such infections under field conditions is still the fecal egg count (FEC). However, the poor sensitivity and cumbersome nature of these tests necessitates the development of a more sensitive, reliable and easy to perform workflow/method. Immunological diagnosis of helminthic infections is still considered as an alternative to the FEC. Therefore, efforts have been made to utilize glutathione-S-transferase (GST), a vitally significant molecule of the adult G. explanatum, for the serodiagnosis of amphistomosis under both laboratory and field conditions. The GST antigen was first affinity purified from the somatic extract of the adult worms since its highest level was recorded in the somatic extracts followed by eggs and the excretory/secretory products. A five-fold affinity purified native GST antigen of about 25 kDa was found to be highly immunogenic as evident from high titre (1:25,600) of the polyclonal antibodies raised in the rabbits. The immunoblotting results revealed differential presence of GST in the adult worms, their eggs and excretory/secretory products. The immunolocalization studies revealed that the vitelline glands are the major source of GST in liver amphistome. Further, we were able to successfully screen animals naturally infected with G. explanatum using anti GST polyclonal antibodies in dot blot assay. High levels of both circulating GST antigen and anti GST antibodies were detected in the serum of the animals naturally infected with G. explanatum, while no cross reactivity was observed with the tropical liver fluke, F. gigantica which often infects the buffalo liver concurrently. The findings of the present study indicate that GST could be used as an important antigen for the diagnosis of G. explanatum infection in Indian water buffaloes.
食源性吸虫病对动物以及生活在牲畜附近的人类构成了重大健康问题，并且仍然被世界卫生组织视为被忽视的热带病。寄生在印度水牛肝脏中的双肠吸虫巨腔吸虫被认为是导致家畜疾病（片形吸虫病）的最常见的寄生虫之一。尽管屠宰场的患病率很高，但由于常规诊断测试的局限性，目前仍未确定这种寄生虫造成的流行病学数据和实际经济损失。在野外条件下确认此类感染的金标准仍然是粪便虫卵计数（FEC）。然而，这些测试的敏感性差且繁琐，因此需要开发更敏感、可靠且易于执行的工作流程/方法。寄生虫感染的免疫学诊断仍然被认为是 FEC 的替代方法。因此，人们努力利用谷胱甘肽-S-转移酶（GST），一种成年巨腔吸虫至关重要的分子，在实验室和野外条件下用于片形吸虫病的血清学诊断。GST 抗原最初是从成虫体提取物中亲和纯化的，因为其最高水平记录在体提取物中，其次是卵和排泄/分泌产物。发现五倍亲和纯化的天然 GST 抗原具有高度免疫原性，因为在兔子中产生的多克隆抗体的效价（1:25,600）很高。免疫印迹结果显示 GST 在成虫、卵和排泄/分泌产物中存在差异。免疫定位研究表明，卵黄腺是肝片形吸虫中 GST 的主要来源。此外，我们能够使用 GST 多克隆抗体在斑点印迹分析中成功筛选自然感染 G. explanatum 的动物。在自然感染 G. explanatum 的动物的血清中检测到 GST 抗原和抗 GST 抗体的高水平，而与经常同时感染水牛肝脏的热带肝吸虫 F. gigantica 没有交叉反应。本研究的结果表明，GST 可作为诊断印度水牛 G. explanatum 感染的重要抗原。
