Quorum sensing (QS) is commonly used in microbial communities and some unicellular parasites to coordinate group behaviours ^1,2 . An example is Trypanosoma brucei, which causes human African trypanosomiasis, as well as the livestock disease, nagana. Trypanosomes are spread by tsetse flies, their transmission being enabled by cell-cycle arrested 'stumpy forms' that are generated in a density-dependent manner in mammalian blood. QS is mediated through a small (<500 Da), non-proteinaceous, stable but unidentified 'stumpy induction factor' ³ , whose signal response pathway has been identified. Although QS is characterized in T. brucei, co-infections with other trypanosome species (Trypanosoma congolense and Trypanosoma vivax) are common in animals, generating the potential for interspecies interactions. Here, we show that T. congolense exhibits density-dependent growth control in vivo and conserves QS regulatory genes, of which one can complement a T. brucei QS signal-blind mutant to restore stumpy formation. Thereafter, we demonstrate that T. congolense-conditioned culture medium promotes T. brucei stumpy formation in vitro, which is dependent on the integrity of the QS signalling pathway. Finally, we show that, in vivo, co-infection with T. congolense accelerates differentiation to stumpy forms in T. brucei, which is also QS dependent. These cross-species interactions have important implications for trypanosome virulence, transmission, competition and evolution in the field.

中文翻译：

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混合感染中的种间群体感应可以操纵锥虫传播潜力。


群体感应 (QS) 通常用于微生物群落和一些单细胞寄生虫中，以协调群体行为^1,2 。一个例子是布氏锥虫，它会导致人类非洲锥虫病以及牲畜疾病，那加那病。锥虫由采采蝇传播，它们的传播是通过细胞周期停滞的“短截形式”实现的，这些“短截形式”是在哺乳动物血液中以密度依赖性方式产生的。 QS 通过小 (<500 id=6>3 ) 介导，其信号响应途径已被确定。虽然 QS 是布氏锥虫的特征，但与其他锥虫物种（刚果锥虫和间日锥虫）的共同感染在动物中很常见，产生种间相互作用的潜力。在这里，我们证明刚果锥虫在体内表现出密度依赖性生长控制并保留 QS 调节基因，其中一个可以补充布氏锥虫 QS 信号盲突变体以恢复树桩形成。 ，我们证明刚果锥虫条件培养基在体外促进布氏锥虫树桩形成，这取决于 QS 信号通路的完整性。最后，我们表明，在体内，刚果锥虫的共感染加速了分化。布氏锥虫中的粗短形式，这也是 QS 依赖性的。这些跨物种相互作用对于锥虫的毒力、传播、竞争和进化具有重要意义。