Establishment of a fluorescence staining method for Schistosoma japonicum miracidia

Currently the diagnosis of schistosomiasis is mainly determined by observing the presence of eggs in host stool samples. Because of the overwhelming number of impurities in the stool, eggs are rarely observed. Therefore, the stool hatching method is used to observe the miracidia in the water. However, the miracidia of Schistosoma japonicum are small and difficult to detect, and missed detection is likely to occur when the infection level is low. In this study, recombinant streptococcal protein G-enhanced green fluorescent protein (rSPG-EGFP) was expressed, purified, and used as a fluorescence staining reagent for miracidia. A preliminary miracidium fluorescence staining method based on antigen and antibody bindingwas established by combining recombinant protein staining with the stool hatching method. The stool hatching method was used to collect the miracidia of S. japonicum, and Schistosoma-positive serum and the recombinant protein were mixed to assess the feasibility of fluorescence staining of miracidia. The miracidia of S. japonicum and Schistosoma turkestanicum were incubated with S. japonicum-positive serum and S. turkestanicum-positive serum, respectively, to identify miracidia species. When the fluorescence staining method was used to observe living miracidia, the miracidiawere labelled by the recombinant protein, and their motility status was not affected.