Institute for Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom.
Elife. 2022 Feb 1;11:e74985. doi: 10.7554/eLife.74985.
Schuster et al. make the important observation that small numbers of trypanosomes can infect tsetse flies, and further argue that this can occur whether the infecting parasites are developmentally 'slender' or 'stumpy'(Schuster et al., 2021). We welcome their careful experiments but disagree that they require a rethink of the trypanosome life-cycle. Instead, the study reveals that stumpy forms are more likely to successfully infect flies, the key limit on parasite transmission, and we predict this advantage would be greatly amplified in tsetse infections in the field. Further, we argue that stumpy forms are defined by a suite of molecular adaptations for life-cycle progression, with morphology being a secondary feature. Finally, their dominance in chronic infections means most natural tsetse infections would involve stumpy forms, even in small numbers. Our interpretation does not require re-evaluation of the obligatory life cycle of the parasite, where stumpy forms are selected to sustain transmission.
舒斯特等人的重要观察结果表明，少量锥体虫可以感染采采蝇，并且进一步认为，无论感染的寄生虫是发育上的“细长”还是“粗短”，这种情况都可能发生（舒斯特等人，2021 年）。我们欢迎他们的精心实验，但不同意他们需要重新考虑锥体虫的生命周期。相反，该研究表明，粗短形式更有可能成功感染苍蝇，这是寄生虫传播的关键限制，我们预测，这一优势在野外的采采蝇感染中会大大放大。此外，我们认为，粗短形式是由一系列用于生命周期进展的分子适应性定义的，形态是次要特征。最后，它们在慢性感染中的优势地位意味着大多数自然采采蝇感染将涉及粗短形式，即使数量很少。我们的解释并不需要重新评估寄生虫的强制性生命周期，在这种生命周期中，粗短形式被选择来维持传播。
