The University of Queensland Diamantina Institute, The University of Queensland, Brisbane, QLD, Australia.
Genetics & Computational Biology Department, QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.
PLoS Pathog. 2019 Jan 23;15(1):e1007513. doi: 10.1371/journal.ppat.1007513. eCollection 2019 Jan.
Mesenteric infection by the parasitic blood fluke Schistosoma bovis is a common veterinary problem in Africa and the Middle East and occasionally in the Mediterranean Region. The species also has the ability to form interspecific hybrids with the human parasite S. haematobium with natural hybridisation observed in West Africa, presenting possible zoonotic transmission. Additionally, this exchange of alleles between species may dramatically influence disease dynamics and parasite evolution. We have generated a 374 Mb assembly of the S. bovis genome using Illumina and PacBio-based technologies. Despite infecting different hosts and organs, the genome sequences of S. bovis and S. haematobium appeared strikingly similar with 97% sequence identity. The two species share 98% of protein-coding genes, with an average sequence identity of 97.3% at the amino acid level. Genome comparison identified large continuous parts of the genome (up to several 100 kb) showing almost 100% sequence identity between S. bovis and S. haematobium. It is unlikely that this is a result of genome conservation and provides further evidence of natural interspecific hybridization between S. bovis and S. haematobium. Our results suggest that foreign DNA obtained by interspecific hybridization was maintained in the population through multiple meiosis cycles and that hybrids were sexually reproductive, producing viable offspring. The S. bovis genome assembly forms a highly valuable resource for studying schistosome evolution and exploring genetic regions that are associated with species-specific phenotypic traits.
牛带绦虫（Schistosoma bovis）是一种寄生性血液吸虫，会引起肠系膜感染，这在非洲和中东地区是一种常见的兽医问题，偶尔也会出现在地中海地区。该物种还有能力与人类寄生虫埃及血吸虫（Schistosoma haematobium）形成种间杂种，在西非已经观察到自然杂交现象，这可能会导致人畜共患传播。此外，物种间等位基因的交换可能会极大地影响疾病动态和寄生虫进化。我们使用 Illumina 和 PacBio 技术生成了 374 Mb 的牛带绦虫基因组组装。尽管感染的宿主和器官不同，但牛带绦虫和埃及血吸虫的基因组序列非常相似，序列一致性高达 97%。这两个物种共享 98%的蛋白质编码基因，平均氨基酸序列一致性为 97.3%。基因组比较确定了基因组中大片段的连续部分（长达数十 kb），在牛带绦虫和埃及血吸虫之间几乎达到 100%的序列一致性。这不太可能是由于基因组保守造成的，进一步证明了牛带绦虫和埃及血吸虫之间存在自然种间杂交。我们的研究结果表明，通过种间杂交获得的外源 DNA 是通过多次减数分裂循环在种群中得以维持的，而且杂种是有性生殖的，能够产生有活力的后代。牛带绦虫基因组组装为研究血吸虫进化和探索与物种特异性表型特征相关的遗传区域提供了非常有价值的资源。
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