Parasite exosomes-derived circulating sja-miR-61 and sja-miR-7-5p as Novel biomarkers for the detection of Schistosoma japonicum infection using TaqMan real-time PCR.

Schistosomiasis, a zoonotic parasitic disease caused by schistosome infection, remains a serious public health concern. However, diagnostic methods with both high sensitivity and specificity or early diagnosis for detecting schistosome infection are still lacking. This study aimed to evaluate the diagnostic potential of parasite-derived exosomes miRNAs in Schistosoma japonicum (S. japonicum) infection. Exosomes were isolated and purified from adult worms and eggs of S. japonicum using ultracentrifugation. Nine highly abundant miRNAs were identified in these exosomes through small RNA sequencing. TaqMan probe-based reverse transcription real-time PCR (RT-qPCR) revealed that serum levels of all nine parasite-derived miRNAs were significantly elevated in infected mice at different time points post-infection. Compared with healthy controls, infected patients exhibited significantly elevated serum levels of sja-miR-61 and sja-miR-7-5p. Receiver operating characteristic (ROC) analysis indicated that the area under the curve (AUC) values for serum sja-miR-61 and sja-miR-7-5p were 0.8750 and 0.8375, respectively, surpassing those of the other miRNAs examined in human serum. The sensitivity and specificity for detecting these miRNAs in human serum were 85.00% and 85.00% for sja-miR-61, and 70.00% and 80.00% for sja-miR-7-5p. When both miRNAs were detected in combination, sensitivity increased to 95.00% with a specificity of 75.00%. In mice, the sensitivity and specificity for detecting sja-miR-7-5p at 2 weeks post-infection were 73.33% and 86.67%, improving to 93.33% and 93.33% at 6 weeks. For sja-miR-61, sensitivity and specificity were 93.33% and 80.00% at 2 weeks, reaching 100.00% and 100.00% at 6 weeks. Serum levels of sja-miR-61 and sja-miR-7-5p dropped to undetectable levels two weeks after praziquantel treatment, underscoring their utility in monitoring treatment response. Furthermore, measurement of sja-miR-61 and sja-miR-7-5p in mice with varying infection intensities showed rising serum levels corresponding to increased worm burdens, with a minimum detection threshold equivalent to an infection with 5 cercariae, highlighting the high sensitivity of this approach for detecting low-level infections in mice. Collectively, the detection of these miRNAs in patient or mouse serum using TaqMan RT-qPCR exhibits good sensitivity and specificity, along with considerable value for early diagnosis and treatment monitoring. sja-miR-61 and sja-miR-7-5p represent promising biomarkers for the diagnosis of schistosomiasis japonica.