Department of Biology, Eberly College of Arts and Sciences, West Virginia University, Morgantown, WV, 26505, USA.
Department of Biology, Washington and Jefferson College, Washington, PA, 15301, USA.
BMC Genomics. 2021 May 31;22(1):400. doi: 10.1186/s12864-021-07729-5.
Tsetse flies are the obligate vectors of African trypanosomes, which cause Human and Animal African Trypanosomiasis. Teneral flies (newly eclosed adults) are especially susceptible to parasite establishment and development, yet our understanding of why remains fragmentary. The tsetse gut microbiome is dominated by two Gammaproteobacteria, an essential and ancient mutualist Wigglesworthia glossinidia and a commensal Sodalis glossinidius. Here, we characterize and compare the metatranscriptome of teneral Glossina morsitans to that of G. brevipalpis and describe unique immunological, physiological, and metabolic landscapes that may impact vector competence differences between these two species.
An active expression profile was observed for Wigglesworthia immediately following host adult metamorphosis. Specifically, 'translation, ribosomal structure and biogenesis' followed by 'coenzyme transport and metabolism' were the most enriched clusters of orthologous genes (COGs), highlighting the importance of nutrient transport and metabolism even following host species diversification. Despite the significantly smaller Wigglesworthia genome more differentially expressed genes (DEGs) were identified between interspecific isolates (n = 326, ~ 55% of protein coding genes) than between the corresponding Sodalis isolates (n = 235, ~ 5% of protein coding genes) likely reflecting distinctions in host co-evolution and adaptation. DEGs between Sodalis isolates included genes involved in chitin degradation that may contribute towards trypanosome susceptibility by compromising the immunological protection provided by the peritrophic matrix. Lastly, G. brevipalpis tenerals demonstrate a more immunologically robust background with significant upregulation of IMD and melanization pathways.
These transcriptomic differences may collectively contribute to vector competence differences between tsetse species and offers translational relevance towards the design of novel vector control strategies.
采采蝇是非洲锥虫的专性载体，可引起人类和动物非洲锥虫病。刚羽化的（新羽化的成虫）采采蝇特别容易被寄生虫定植和发育，但我们对其原因的理解仍然很零碎。采采蝇肠道微生物组主要由两种γ变形菌组成，一种是必不可少的古老共生菌 Wigglesworthia glossinidia 和一种共生菌 Sodalis glossinidius。在这里，我们对刚羽化的 Glossina morsitans 的宏转录组进行了表征和比较，并描述了独特的免疫、生理和代谢景观，这些景观可能会影响这两个物种之间的媒介能力差异。
在宿主成虫变态后，立即观察到 Wigglesworthia 的活跃表达谱。具体来说，“翻译、核糖体结构和生物发生”之后是“辅酶转运和代谢”是最丰富的同源基因（COG）簇，突出了营养物质转运和代谢的重要性，即使在宿主物种多样化之后也是如此。尽管 Wigglesworthia 基因组明显较小，但在种间分离株之间鉴定出更多的差异表达基因（DEGs）（n=326，约占编码蛋白基因的 55%），而在相应的 Sodalis 分离株之间鉴定出的差异表达基因（n=235，约占编码蛋白基因的 5%）。这可能反映了宿主共同进化和适应的差异。Sodalis 分离株之间的 DEGs 包括参与几丁质降解的基因，这可能通过破坏围食膜提供的免疫保护而导致锥虫易感性。最后，G. brevipalpis 的刚羽化个体表现出更强的免疫背景，其 IMD 和黑化途径显著上调。
这些转录组差异可能共同导致了采采蝇物种之间媒介能力的差异，并为设计新型媒介控制策略提供了转化相关性。
