Conserved surface-exposed linear epitopes of Echinococcus multilocularis thioredoxin peroxidase enable non-invasive diagnosis of alveolar echinococcosis in intermediate host
4 affiliations
- 1Key Laboratory of Animal Disease Diagnostics and Immunology, Ministry of Agriculture, MOE International Joint Collaborative Research Laboratory for Animal Health & Food Safety, College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China
- 2Academy of Animal Science and Veterinary, Qinghai Provincial Key Laboratory of Pathogen Diagnosis for Animal Diseases and Green Technical Research for Prevention and Control, Qinghai University, Xining, China
- 3The Haixi Prefecture Center for Animal Disease Control and Prevention, Delingha, China
- 4The Wulan County Center for Disease Control and Prevention, Wulan, China
Abstract
Alveolar echinococcosis (AE) is a severe zoonotic parasitic disease caused by the larval stage of Echinococcus multilocularis, for which early and accurate diagnosis remains challenging. In this study, we targeted E. multilocularis thioredoxin peroxidase (EmTPx), a highly abundant excretory/secretory protein conserved across the genus Echinococcus, for diagnostic development. Monoclonal antibodies (mAbs) against EmTPx were generated, and two linear B‑cell epitopes, 174HPGSK178 and 189SFMSS193, were identified. Both epitopes are strictly conserved within Echinococcus but markedly divergent from mammalian host sequences. Structural modeling revealed that the epitopes are surface‑exposed, with 174HPGSK178 located in a flexible loop and 189SFMSS193 adjacent to an α‑helix, conformations favorable for antibody recognition. Two ELISA methods were established using the epitope‑specific mAbs. The blocking ELISA showed moderate diagnostic performance. More importantly, the sandwich ELISA enabled direct detection of EmTPx antigen in fecal samples of intermediate hosts, revealing a detection rate of 85% in mouse feces at an early infection stage. With a linear range of 0–250 ng/mL, a cutoff of 0.1724, and intra‑ and inter‑assay precision below 10%, this sandwich ELISA demonstrated robust analytical performance. In conclusion, this proof-of-concept study identifies two evolutionarily conserved and structurally exposed EmTPx epitopes and demonstrates their potential utility for the development of monoclonal antibody-based approaches for non-invasive detection of echinococcosis. Author summary: Alveolar echinococcosis (AE) is a life-threatening parasitic disease caused by the larval stage of Echinococcus multilocularis. Early diagnosis remains challenging, as current blood-based tests detect host antibodies but often fail in immunocompromised individuals and cannot reliably distinguish active from past infection. In this study, we developed a non-invasive diagnostic approach that directly detects a parasite excretory/secretory protein called thioredoxin peroxidase (EmTPx) in fecal samples. We generated monoclonal antibodies targeting two specific regions of EmTPx that are highly conserved among Echinococcus species yet markedly different from mammalian TPx homologs, ensuring specific recognition of the parasite. Using these antibodies, we constructed a sandwich ELISA and successfully detected EmTPx in the feces of experimentally infected mice at an early stage of infection. This finding supports a mechanistic model in which parasite proteins released from hepatic lesions reach the intestinal lumen through hepatobiliary transport, thereby enabling non-invasive fecal detection. Beyond providing a theoretical foundation for discovering additional coproantigen targets, this approach offers a promising tool for early diagnosis and large-scale screening of AE, particularly in resource-limited endemic settings where current diagnostic methods are unavailable or insufficient.
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BibTeX
@article{zheng2026conserved,
title = {{Conserved surface-exposed linear epitopes of Echinococcus multilocularis thioredoxin peroxidase enable non-invasive diagnosis of alveolar echinococcosis in intermediate host}},
author = {Lijuan Zheng and Wenjing Zhi and Mengjie Chu and Xinyi Zhou and Yong Fu and Chen Xin and Baoping Li and Lingzhi Pengmao and Zhendong Xin and Yihui Wu and Xuejun Ji and Anni Zhang and Changjie Qian and Zhen Wang and Chenye Jin and Yun Han and Zhijun Zhang and Fuyun Chen and Gongguan Liu},
journal = {PLOS Neglected Tropical Diseases},
year = {2026},
month = sep,
doi = {10.1371/journal.pntd.0014755},
url = {https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014755},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Conserved surface-exposed linear epitopes of Echinococcus multilocularis thioredoxin peroxidase enable non-invasive diagnosis of alveolar echinococcosis in intermediate host
AU - Lijuan Zheng
AU - Wenjing Zhi
AU - Mengjie Chu
AU - Xinyi Zhou
AU - Yong Fu
AU - Chen Xin
AU - Baoping Li
AU - Lingzhi Pengmao
AU - Zhendong Xin
AU - Yihui Wu
AU - Xuejun Ji
AU - Anni Zhang
AU - Changjie Qian
AU - Zhen Wang
AU - Chenye Jin
AU - Yun Han
AU - Zhijun Zhang
AU - Fuyun Chen
AU - Gongguan Liu
PY - 2026
DA - 2026/09/22
JO - PLOS Neglected Tropical Diseases
DO - 10.1371/journal.pntd.0014755
UR - https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014755
AB - Alveolar echinococcosis (AE) is a severe zoonotic parasitic disease caused by the larval stage of Echinococcus multilocularis, for which early and accurate diagnosis remains challenging. In this study, we targeted E. multilocularis thioredoxin peroxidase (EmTPx), a highly abundant excretory/secretory protein conserved across the genus Echinococcus, for diagnostic development. Monoclonal antibodies (mAbs) against EmTPx were generated, and two linear B‑cell epitopes, 174HPGSK178 and 189SFMSS193, were identified. Both epitopes are strictly conserved within Echinococcus but markedly divergent from mammalian host sequences. Structural modeling revealed that the epitopes are surface‑exposed, with 174HPGSK178 located in a flexible loop and 189SFMSS193 adjacent to an α‑helix, conformations favorable for antibody recognition. Two ELISA methods were established using the epitope‑specific mAbs. The blocking ELISA showed moderate diagnostic performance. More importantly, the sandwich ELISA enabled direct detection of EmTPx antigen in fecal samples of intermediate hosts, revealing a detection rate of 85% in mouse feces at an early infection stage. With a linear range of 0–250 ng/mL, a cutoff of 0.1724, and intra‑ and inter‑assay precision below 10%, this sandwich ELISA demonstrated robust analytical performance. In conclusion, this proof-of-concept study identifies two evolutionarily conserved and structurally exposed EmTPx epitopes and demonstrates their potential utility for the development of monoclonal antibody-based approaches for non-invasive detection of echinococcosis. Author summary: Alveolar echinococcosis (AE) is a life-threatening parasitic disease caused by the larval stage of Echinococcus multilocularis. Early diagnosis remains challenging, as current blood-based tests detect host antibodies but often fail in immunocompromised individuals and cannot reliably distinguish active from past infection. In this study, we developed a non-invasive diagnostic approach that directly detects a parasite excretory/secretory protein called thioredoxin peroxidase (EmTPx) in fecal samples. We generated monoclonal antibodies targeting two specific regions of EmTPx that are highly conserved among Echinococcus species yet markedly different from mammalian TPx homologs, ensuring specific recognition of the parasite. Using these antibodies, we constructed a sandwich ELISA and successfully detected EmTPx in the feces of experimentally infected mice at an early stage of infection. This finding supports a mechanistic model in which parasite proteins released from hepatic lesions reach the intestinal lumen through hepatobiliary transport, thereby enabling non-invasive fecal detection. Beyond providing a theoretical foundation for discovering additional coproantigen targets, this approach offers a promising tool for early diagnosis and large-scale screening of AE, particularly in resource-limited endemic settings where current diagnostic methods are unavailable or insufficient.
SN - 1935-2735
ER -