Arista-Regalado Aurora Dolores, Barba-León Jeannette, Bustamante Victor Humberto, Flores-Valdez Mario Alberto, Gaona Jorge, Fajardo-Guerrero Maira Juliana
Microbiology and Pathology department Centro, Universitario de Ciencias de la Salud, Universidad de Guadalajara, Guadalajara, Jalisco 44340, Mexico.
Public Health department Centro Universitario de Ciencias Biológicas y Agropecuarias, Universidad de Guadalajara, Zapopan, Jalisco 45200, Mexico.
J Food Prot. 2023 May;86(5):100085. doi: 10.1016/j.jfp.2023.100085. Epub 2023 Mar 31.
Salmonella enterica is a foodborne pathogen that can be internalized into fresh produce. Most of the Salmonella virulence genes are clustered in regions denominated Salmonella Pathogenicity Islands (SPI). SPI-1 encodes a Type Three Secretion System (T3SS-1) and effector proteins that allow the internalization of Salmonella into animal cells. HilD is a transcriptional regulator that induces the expression of SPI-1 genes and other related virulence genes located outside of this island. Here, we assessed the role of hilD in the internalization of Salmonella Newport and Typhimurium into cherry tomatoes, by evaluating either an isolate from an avocado orchard, S. Newport-45 or the laboratory strain S. Typhimurium SL1344 and their isogenic mutants in hilD. The internalization of these bacteria was carried out by using a temperature gradient of 12°C. The transcription of hilD and invA was tested by qRT-PCR experiments. Our results show that S. Newport-45 hilD mutant viable cells obtained from the interior of the fruit were decreased (2.7-fold), compared with those observed for S. Typhimurium SL1344. Interestingly, at 3 days postinoculation, the cells recovered from S. Newport-45 hilD mutant were similar to those recovered from all the strains evaluated, suggesting that hilD is required only for the initial internalization of S. Newport.
肠炎沙门氏菌是一种食源性病原体，可内化至新鲜农产品中。大多数沙门氏菌毒力基因聚集在称为沙门氏菌致病岛（SPI）的区域。SPI-1编码一种三型分泌系统（T3SS-1）和效应蛋白，使沙门氏菌能够内化至动物细胞中。HilD是一种转录调节因子，可诱导SPI-1基因以及位于该岛外的其他相关毒力基因的表达。在这里，我们通过评估来自鳄梨果园的分离株纽波特沙门氏菌-45或实验室菌株鼠伤寒沙门氏菌SL1344及其hilD基因的同基因突变体，来评估hilD在纽波特沙门氏菌和鼠伤寒沙门氏菌内化至樱桃番茄中的作用。这些细菌的内化是在12°C的温度梯度下进行的。通过qRT-PCR实验检测hilD和invA的转录情况。我们的结果表明，与鼠伤寒沙门氏菌SL1344相比，从果实内部获得的纽波特沙门氏菌-45 hilD突变体活细胞数量减少了（2.7倍）。有趣的是，在接种后3天，从纽波特沙门氏菌-45 hilD突变体中回收的细胞与从所有评估菌株中回收的细胞相似，这表明hilD仅对纽波特沙门氏菌的初始内化是必需的。
