The freshwater snail Oncomelania hupensis is the obligate intermediate host for Schistosoma japonicum in China. Transcriptomic examination of snail–schistosome interactions can provide valuable information of host response at physiological and immune levels. To investigate S. japonicum-induced changes in O. hupensis gene expression, we utilized high-throughput sequencing to identify transcripts that were differentially expressed between infected snails and their uninfected controls at two key time-point, Day 7 and Day 30 after challenge. Time-series transcriptomic profiles were analyzed using R package DESeq 2, followed by GO, KEGG and (weighted gene correlation network analysis) WGCNA analysis to elucidate and identify important molecular mechanism, and subsequently understand host–parasite relationship. The identified unigenes was verified by bioinformatics and real-time PCR. Possible adaptation molecular mechanisms of O. hupensis to S. japonicum challenge were proposed. Transcriptomic analyses of O. hupensis by S. japonicum invasion yielded billion reads including 92,144 annotated transcripts. Over 5000 differentially expressed genes (DEGs) were identified by pairwise comparisons of infected libraries from two time points to uninfected libraries in O. hupensis. In total, 6032 gene ontology terms and 149 KEGG pathways were enriched. After the snails were infected with S. japonicum on Day 7 and Day 30, DEGs were shown to be involved in many key processes associated with biological regulation and innate immunity pathways. Gene expression patterns differed after exposure to S. japonicum. Using WGCNA, 16 modules were identified. Module-trait analysis identified that a module involved in RNA binding, ribosome, translation, mRNA processing, and structural constituent of ribosome were strongly associated with S. japonicum invasion. Many of the genes from enriched KEGG pathways were involved in lysosome, spliceosome and ribosome, indicating that S. japonicum invasion may activate the regulation of ribosomes and immune response to infection in O. hupensis. Our analysis provided a temporally dynamic gene expression pattern of O. hupensis by S. japonicum invasion. The identification of gene candidates serves as a foundation for future investigations of S. japonicum infection. Additionally, major DEGs expression patterns and putative key regulatory pathways would provide useful information to construct gene regulatory networks between host-parasite crosstalk.

中文翻译：

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日本血吸虫入侵揭示的湖北钉螺转录组时间变化。

淡水螺钉螺是我国日本血吸虫的专性中间宿主。蜗牛-血吸虫相互作用的转录组学检查可以在生理和免疫水平上提供宿主反应的有价值信息。为了研究 S. japonicum 诱导的 O. hupensis 基因表达的变化，我们利用高通量测序来鉴定在两个关键时间点（攻击后第 7 天和第 30 天）受感染蜗牛与其未感染对照之间差异表达的转录物。使用 R 包 DESeq 2 分析时间序列转录组图谱，然后进行 GO、KEGG 和（加权基因相关网络分析）WGCNA 分析，以阐明和确定重要的分子机制，并随后了解宿主-寄生虫关系。通过生物信息学和实时PCR验证鉴定的unigenes。提出了 O. hupensis 对 S. japonicum 挑战的可能适应分子机制。S. japonicum 入侵对 O. hupensis 的转录组学分析产生了十亿个读数，包括 92,144 个带注释的转录本。超过 5000 个差异表达基因 (DEG) 通过从两个时间点的受感染文库与 O. hupensis 中未感染文库的成对比较来鉴定。总共富集了 6032 个基因本体术语和 149 个 KEGG 通路。在蜗牛在第 7 天和第 30 天感染日本血吸虫后，DEG 被证明参与了与生物调节和先天免疫途径相关的许多关键过程。暴露于日本血吸虫后，基因表达模式有所不同。使用 WGCNA，确定了 16 个模块。模块性状分析发现，涉及 RNA 结合、核糖体、翻译、mRNA 加工和核糖体结构成分的模块与日本血吸虫入侵密切相关。来自丰富的KEGG途径的许多基因涉及溶酶体，剪接体和核糖体，表明日本血吸虫入侵可能激活核糖体的调节和对感染的免疫反应。我们的分析提供了日本血吸虫入侵 O. hupensis 的时间动态基因表达模式。候选基因的鉴定为未来研究日本血吸虫感染奠定了基础。此外，主要的 DEGs 表达模式和推定的关键调控途径将为构建宿主-寄生虫串扰之间的基因调控网络提供有用的信息。