Department of Craniofacial Development, Dental Institute, School of Medicine, King's College London, London, United Kingdom.
PLoS One. 2012;7(11):e49745. doi: 10.1371/journal.pone.0049745. Epub 2012 Nov 27.
Melioidosis is a serious infectious disease endemic to Southeast Asia and Northern Australia. This disease is caused by the Gram-negative bacterium Burkholderia pseudomallei; Burkholderia thailandensis is a closely-related organism known to be avirulent in humans. B. thailandensis has not previously been used to infect Drosophila melanogaster. We examined the effect of B. thailandensis infection on fly survival, on antimicrobial peptide expression, and on phagocytic cells. In the fruit fly, which possesses only an innate immune system, B. thailandensis is highly virulent, causing rapid death when injected or fed. One intriguing aspect of this infection is its temperature dependence: infected flies maintained at 25°C exhibit rapid bacterial proliferation and death in a few days, while infected animals maintained at 18°C exhibit very slow bacterial proliferation and take weeks to die; this effect is due in part to differences in immune activity of the host. Death in this infection is likely due at least in part to a secreted toxin, as injection of flies with sterile B. thailandensis-conditioned medium is able to kill. B. thailandensis infection strongly induces the expression of antimicrobial peptides, but this is insufficient to inhibit bacterial proliferation in infected flies. Finally, the function of fly phagocytes is not affected by B. thailandensis infection. The high virulence of B. thailandensis in the fly suggests the possibility that this organism is a natural pathogen of one or more invertebrates.
类鼻疽是一种严重的传染病，流行于东南亚和澳大利亚北部。这种疾病是由革兰氏阴性细菌鼻疽伯克霍尔德氏菌引起的；类鼻疽假单胞菌是一种密切相关的生物体，已知对人类无毒性。类鼻疽假单胞菌以前从未被用于感染黑腹果蝇。我们研究了类鼻疽假单胞菌感染对苍蝇存活率、抗菌肽表达和吞噬细胞的影响。在果蝇中，它只拥有先天免疫系统，类鼻疽假单胞菌具有高度的毒力，当注射或喂食时会导致迅速死亡。这种感染的一个有趣方面是它对温度的依赖性：在 25°C 下维持的感染苍蝇会在几天内迅速增殖和死亡，而在 18°C 下维持的感染动物则增殖非常缓慢，需要数周才能死亡；这种效应部分归因于宿主免疫活性的差异。这种感染导致的死亡至少部分归因于一种分泌毒素，因为向苍蝇注射无菌的类鼻疽假单胞菌条件培养基就能杀死苍蝇。类鼻疽假单胞菌感染强烈诱导抗菌肽的表达，但这不足以抑制感染苍蝇中的细菌增殖。最后，苍蝇吞噬细胞的功能不受类鼻疽假单胞菌感染的影响。类鼻疽假单胞菌在果蝇中的高毒力表明，这种生物体可能是一种或多种无脊椎动物的天然病原体。
