构建沙门菌-斑马鱼感染模型，研究幼年斑马鱼体内的异源自噬。用不同浓度鼠伤寒沙门菌浸染受精后72 h的幼年斑马鱼，绘制7 d内斑马鱼的存活率曲线以确定适宜的细菌感染量。以上述细菌量感染斑马鱼后，荧光显微镜下观察发光菌在体内的播散情况；不同时间计数细菌菌落并用蛋白免疫印迹法检测自噬相关蛋白Lc3和P62的表达，同时在电子显微镜下观察自噬体结构。结果显示，以1×10⁹ cfu/ml细菌量感染斑马鱼后，2 d内斑马鱼存活率为100%，第3天开始出现死亡。荧光显微镜下发现，感染后4 h鱼体中有细菌侵入，3 d后细菌扩散至全身。细菌计数结果显示，整条鱼感染的细菌量随时间延长不断增加；但感染后10 h侵入鱼体细胞中的菌量显著低于8 h。蛋白免疫印迹结果显示，感染后8 h Lc3-Ⅱ表达显著升高，P62表达明显降低。透射电子显微镜下，感染后8 h幼鱼细胞中可观察到自噬体和自噬溶酶体结构。以上结果提示，用鼠伤寒沙门菌浸染幼年斑马鱼构建的模型可用于追踪病原菌感染引起的异源自噬的动态变化。

Establishing a Salmonella-zebrafish infection model to study the xenophagy. Zebrafish larvae at 72 h post-fertilization were exposed to different doses of Salmonella typhimurium (S. typhimurium). The survival curve of zebrafish larvae was used to determine the appropriate dose of bacteria. After infection by the above dose, the distribution of green fluorescent protein (GFP)-tagged S. typhimurium in zebrafish larvae was observed under a fluorescence microscope. The bacteria count and expression of autophagy protein Lc3-Ⅱand P62 were used to detect the changes in autophagy, and the autophagosome was observed under the transmission electron microscope. The results revealed that after exposure to S. typhimurium at a final dose of 1×109 cfu/ml, the survival curve was 100%, and the larvae began to die on the third day. Fluorescence microscopy found that bacteria had invaded into the larvae at 4 h after infection, and spreaded around the body in 3 d. The bacteria amount in whole-larvae bacteria was increasing over time, but the amount of intracellular bacteria in the larvae at 10 h after infection was significantly less than that at 8 h. Western blotting analysis showed that Lc3-Ⅱ was significantly increased, but P62 was reduced. Under the transmission electron microscope, autophagosome and autolysosome were observed in larvae at 8 h after infection. According to the above results, Salmonella-zebrafish model can be used to track the dynamic changes in autophagy induced by pathogen infection.