Functional Analysis of Schistosoma japonicum Aminopeptidase N

Schistosoma japonicum aminopeptidase N (SjAPN) is a conserved M1 family metalloprotease, but its role in schistosome biology remains unclear. Bioinformatics analysis, quantitative PCR, RNA interference, confocal microscopy, and scanning electron microscopy were used to characterize SjAPN expression and function. SjAPN contained typical metalloprotease domains and showed high sequence similarity to homologs from other trematodes. Its transcription increased during schistosome development, was higher in female worms than in males, and was mainly detected in the anterior region of both sexes. RNA interference effectively reduced SjAPN transcript levels in adult worms. Functional analysis showed that SjAPN silencing was associated with reduced egg output during in vitro culture, altered vitellocyte staining, and tegumental surface changes in female worms. In the in vivo experiment, worm burden was significantly lower in the SjAPN RNAi group than in the NC group, but not in the PBS group. These findings indicate that SjAPN transcript levels are associated with changes in the development and reproductive biology of S. japonicum, particularly in female worms, and may be a potential target for further studies on schistosome control. Further studies are required to determine whether these phenotypes are mediated by reduced SjAPN protein abundance or enzymatic activity.