Ultrastructural Observation and Gene Expression Profiling of Schistosoma japonicum Derived from Two Natural Reservoir Hosts, Water Buffalo and Yellow Cattle

Water buffalo and yellow cattle are the two of the most important natural reservoir hosts for Schistosoma japonicum in endemic areas of China, although their susceptibility differs, with water buffalo being less conducive to the growth and development of S. japonicum. Results from the current study show that the general morphology and ultrastructure of adult schistosomes derived from the two hosts also differed. Using high-throughput microarray technology, we also compared the gene expression profiles of adult schistosomes derived from the two hosts. We identified genes that were differentially expressed in worms from the two natural hosts. Further analysis revealed that genes associated with protein kinase and phosphatase, the stimulus response, and lipid and nucleotide metabolism were overexpressed, whereas genes associated with reproduction, anatomical structure morphogenesis and multifunctional motif were underexpressed in schistosomes from water buffalo. These differentially expressed genes were mainly involved in nucleotide, energy, lipid metabolism, energy metabolism, transcription, transport and signaling pathway. This suggests that they are key molecules affecting the survival and development of schistosomes in different natural host species. The results of this study add to current understanding of the interplay between parasites and their natural hosts, and provide valuable information for the screening of vaccine candidates or new drug targets against schistosomiasis in the natural reservoir hosts in endemic areas.在中国日本血吸虫（Schistosoma japonicum）流行区，水牛与黄牛是该寄生虫最为重要的两种自然储存宿主，尽管二者对寄生虫的易感性存在显著差异：水牛更不利于日本血吸虫的生长与发育。本研究结果显示，源自两种宿主的成虫血吸虫，其大体形态与超微结构亦存在差异。本研究还采用高通量微阵列技术（high-throughput microarray technology），比较了源自两种宿主的成虫血吸虫的基因表达谱，并鉴定出了在两种天然宿主来源的虫体内差异表达的基因。进一步分析表明，在水牛来源的血吸虫中，与蛋白激酶、磷酸酶、应激响应以及脂质和核苷酸代谢相关的基因呈现过表达状态，而与生殖、解剖结构形态发生及多功能基序相关的基因则呈现低表达状态。这些差异表达基因主要参与核苷酸代谢、能量代谢、脂质代谢，以及转录、运输与信号通路等生物学过程。这提示它们是影响血吸虫在不同天然宿主体内存活与发育的关键分子。本研究结果加深了学界对寄生虫与其天然宿主之间互作关系的认知，并为流行区自然储存宿主的血吸虫病疫苗候选株筛选或新型药物靶点开发提供了极具价值的参考信息。