Detection of Schistosoma japonicum cercariae using environmental DNA assay

doi:10.12140/j.issn.1000-7423.2025.04.023

Abstract

Abstract:

To investigate the feasibility and sensitivity of environmental DNA (eDNA) assay for detection of Schistosoma japonicum cercariae, cercariae shed from S. japonicum-infected Oncomelania hupensis snail were collected,with 1, 5, 10, 15, 20, and > 30 cercariae as experimental groups and 0 cercaria as the control group. After standing for 24 hours, cercariae were filtered and water samples were collected. Then, eDNA was enriched using membrane filter with 0.22 μm in pore size, and extracted using the Water DNA Isolation Kit. The Real-time fluorescence quantitative PCR (qPCR) assay was performed with S. japonicum mitochondrial cytochrome c coxidase subunit 1 (cox1) and 16S rRNA genes as specific primers to detect eDNA in each group. The cycle threshold (Ct value) was recorded, and the associations of Ct value with cercariae density and eDNA concentration were examined using Spearman correlation analysis. qPCR assay detected S. japonicum cercariae DNA in all experimental groups of different densities of cercariae with the primers cox1 and 16S rRNA. The DNA concentrations were 2.4, 1.0, 0.4, 1.5, 1.3, and 9.4 μg/ml, respectively. Spearman correlation analysis revealed that the cercariae density significantly negatively correlated with the Ct value with the primer cox1 gene (r = -0.886, P < 0.05), and negatively correlated with the Ct value with the primer 16S rRNA gene (r = -0.771, P > 0.05). The eDNA concentration negatively correlated with the Ct value with the primer cox1 gene (r = -0.314, P > 0.05) and the primer 16S rRNA gene (r = -0.200, P > 0.05). These findings suggest that eDNA assay is feasible for detection of S. japonicum cercariae with high timeliness, which has the value for early warning of environments at a high risk of S. japonicum infections.

Key words: Schistosoma japonicum, Environmental DNA, Schistosome cercaria, Oncomelania hupensis

CLC Number:

R383.24

WEN Yusong, XU Hui, QIU Tingting, ZHAO Qin, LI Jie, XU Jianrui, ZENG Xiaojun, Ding Sheng, LI Zhaojun. Detection of Schistosoma japonicum cercariae using environmental DNA assay[J]. CHINESE JOURNAL OF PARASITOLOGY AND PARASITIC DISEASES, 2025, 43(4): 596-599.

Figures/Tables 2

References 23

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组别	cox1		16S rRNA
组别	扩增成功率	Ct平均值	扩增成功率	Ct平均值
0条尾蚴	0/3		0/3
1条尾蚴	1/3	36.69	2/3	37.32
5条尾蚴	2/3	37.56	3/3	38.51
10条尾蚴	3/3	31.71	3/3	31.63
15条尾蚴	3/3	35.24	3/3	33.26
20条尾蚴	3/3	31.64	3/3	31.90
> 30条尾蚴	3/3	22.72	3/3	24.61