Background

Insects models are excellent models of the innate immune system, as they are free from the influences of vertebrate adaptive immunity. Crickets are hemimetabolous insects belonging to the order Orthopteran order that have not been as extensively characterized as other holometabolous insects, and may provide new insights into the insect immune responses. In this study, we aim to characterize the innate immune responses of the common house cricket, Acheta domesticus in response to a human pathogenic bacterium E. coli K1.

Methods

Crickets were injected with sterile buffer, live E. coli K1 or heat-killed E. coli K1. Physiological effects such as mortality and weight change of the crickets were determined 24-, 48- and 72-h post injection while immunological effects such as hemocyte counts, bacteremia, phenoloxidase and lysozyme activity of the crickets were measured at 2- and 24-h post-injection.

Results

The injection of E. coli K1 in crickets resulted in >85% mortality 3-days post injection, accompanied by significant weight loss. E. coli K1 injection caused a significant increase in both phenoloxidase and lysozyme activities in cricket hemolymphs 24-h post injection. Live E. coli K1 injected crickets resulted in a significant reduction in circulating hemocytes 24-h post injection which was not observed in other treatment groups. This was consistent with the resolution of bacteremia observed 24-h post infection in live E. coli K1 injected crickets.

Conclusion

Our study provides new insights on the innate immune response to pathogenic E. coli K1 in a cricket model.

中文翻译：

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研究家蟋蟀、Acheta domesticus 对致病性大肠杆菌 K1 的免疫反应

背景

昆虫模型是先天免疫系统的优秀模型，因为它们不受脊椎动物适应性免疫的影响。蟋蟀是属于直翅目昆虫的半代谢昆虫，没有像其他全代谢昆虫那样被广泛表征，并且可能为昆虫免疫反应提供新的见解。在这项研究中，我们旨在描述普通家蟋蟀Acheta domesticus对人类致病菌大肠杆菌K1 的先天免疫反应。

方法

蟋蟀注射无菌缓冲液、活大肠杆菌K1 或热灭活大肠杆菌K1。注射后 24、48 和 72 小时测定蟋蟀的生理影响，如死亡率和体重变化，而在 2 和 24 小时测定蟋蟀的血细胞计数、菌血症、酚氧化酶和溶菌酶活性等免疫影响注射后。

结果

在蟋蟀中注射大肠杆菌K1 导致注射后 3 天死亡率 > 85%，并伴有显着的体重减轻。大肠杆菌K1 注射导致注射后 24 小时蟋蟀血淋巴中的酚氧化酶和溶菌酶活性显着增加。注射活大肠杆菌K1 的蟋蟀导致注射后 24 小时循环血细胞显着减少，这在其他治疗组中未观察到。这与在活大肠杆菌K1 注射蟋蟀感染后 24 小时观察到菌血症的消退是一致的。

结论

我们的研究为蟋蟀模型中对致病性大肠杆菌K1的先天免疫反应提供了新的见解。