Evaluation of the immunodiagnostic potential of recombinant Spm2 antigen using indirect ELISA for detecting Theileria annulata infection in cattle

IF 2.2 2区农林科学 Q2 PARASITOLOGY

Veterinary parasitology Pub Date : 2025-07-07 DOI:10.1016/j.vetpar.2025.110542

Aquil Mohmad , B.C. Saravanan , K.R. Baghel , A. Annajarvis , R. Saravanan , Vinodh Kumar Obli Rajendran , Ajay Kumar , M. Sankar , A.K. Tewari , S. Ghosh

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引用次数: 0

Abstract

Bovine tropical theileriosis, caused by Theileria annulata, is an economically important disease that reduces livestock productivity through decreased milk yield, high morbidity, and mortality, particularly in exotic and cross-bred cattle. Timely diagnosis and treatment are crucial for effectively managing susceptible animals. This study aimed to develop a robust serological diagnostic tool targeting the sporozoite and macroschizont 2 antigen (Spm2), a protein expressed across multiple parasite stages including sporozoites, macroschizonts, and piroplasms. The recombinant Spm2 (rSpm2) protein was cloned, expressed in a prokaryotic system, and purified via Ni-NTA chromatography, with its immunoreactivity confirmed through Western blot (WB) analysis using known T. annulata-positive serum samples. An indirect rSpm2-ELISA (Enzyme-linked immunosorbent assay) was developed and standardized using 23 known positive and 30 known negative sera samples. Its diagnostic potential was evaluated by analyzing 360 field serum samples and comparing the results with a previously validated rTaSP-ELISA. The rSpm2-ELISA detected T. annulata infection in 78.9 % of cattle sera, compared to 83.9 % with rTaSP-ELISA. Notably, rSpm2 exhibited no cross-reactivity with reference-positive sera from cattle infected with Babesia bigemina and Anaplasma marginale in WB and ELISA assays. The sensitivity and specificity of the rSpm2-ELISA were determined to be 93.7 % and 98.3 %, respectively, highlighting its strong diagnostic potential. This study is the first comparative serological evaluation of tropical theileriosis using rSpm2-ELISA and rTaSP-ELISA. The high accuracy, specificity, and sensitivity of rSpm2-ELISA make it a promising tool for serological surveillance of tropical theileriosis, particularly in regions where T. parva is absent.

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用间接ELISA法评价重组Spm2抗原检测牛环孢杆菌感染的免疫诊断潜力

由环纹伊勒菌引起的牛热带伊勒菌病是一种经济上重要的疾病，它通过减少产奶量、高发病率和死亡率来降低牲畜生产力，特别是在外来和杂交牛中。及时诊断和治疗对于有效管理易感动物至关重要。本研究旨在开发一种针对孢子子和大分裂体2抗原（Spm2）的强大血清学诊断工具，Spm2是一种在包括孢子子、大分裂体和螺质在内的多个寄生虫阶段表达的蛋白质。克隆了重组Spm2 （rSpm2）蛋白，在原核系统中表达，并通过Ni-NTA层析纯化，通过Western blot （WB）分析已知T. annulata阳性血清样品，证实了其免疫反应性。使用23个已知阳性和30个已知阴性血清样本，开发并标准化了间接rSpm2-ELISA（酶联免疫吸附测定）。通过分析360份现场血清样本，并将结果与先前验证的rTaSP-ELISA进行比较，评估其诊断潜力。rSpm2-ELISA检测到牛血清中环虫感染率为78.9% %，而rTaSP-ELISA检测到环虫感染率为83.9% %。值得注意的是，在WB和ELISA检测中，rSpm2与感染巴贝斯虫和边缘无原体的牛的参考阳性血清没有交叉反应。rSpm2-ELISA的敏感性为93.7 %，特异性为98.3% %，具有较强的诊断潜力。本研究首次采用rSpm2-ELISA和rTaSP-ELISA对热带血吸虫病进行血清学比较评价。rSpm2-ELISA的高准确性、特异性和敏感性使其成为热带血吸虫病血清学监测的有希望的工具，特别是在没有T. parva的地区。

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来源期刊

Veterinary parasitology 农林科学-寄生虫学

CiteScore

5.30

自引率

7.70%

发文量

126

审稿时长

36 days

期刊介绍： The journal Veterinary Parasitology has an open access mirror journal,Veterinary Parasitology: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review. This journal is concerned with those aspects of helminthology, protozoology and entomology which are of interest to animal health investigators, veterinary practitioners and others with a special interest in parasitology. Papers of the highest quality dealing with all aspects of disease prevention, pathology, treatment, epidemiology, and control of parasites in all domesticated animals, fall within the scope of the journal. Papers of geographically limited (local) interest which are not of interest to an international audience will not be accepted. Authors who submit papers based on local data will need to indicate why their paper is relevant to a broader readership. Parasitological studies on laboratory animals fall within the scope of the journal only if they provide a reasonably close model of a disease of domestic animals. Additionally the journal will consider papers relating to wildlife species where they may act as disease reservoirs to domestic animals, or as a zoonotic reservoir. Case studies considered to be unique or of specific interest to the journal, will also be considered on occasions at the Editors'' discretion. Papers dealing exclusively with the taxonomy of parasites do not fall within the scope of the journal.