Departmento de Microbiologia, Universidade Federal de Viçosa (UFV), Viçosa, Minas Gerais, Brazil.
Departamento de Biologia Geral, Universidade Federal de Viçosa (UFV), Viçosa, Minas Gerais, Brazil.
Microb Pathog. 2021 Mar;152:104730. doi: 10.1016/j.micpath.2021.104730. Epub 2021 Jan 11.
Salmonella is a food and waterborne pathogen responsible for outbreaks worldwide, and it can survive during passage through the stomach and inside host phagocytic cells. Virulence genes are required for infection and survival in macrophages, and some are under the regulation of the quorum sensing (QS) system. This study investigated the influence of the autoinducer 1 (AI-1), N-dodecanoyl-homoserine lactone (C12-HSL), on the virulence of Salmonella PT4 using Galleria mellonella as an infection model. Salmonella PT4 was grown in the presence and absence of C12-HSL under anaerobic conditions for 7 h, and the expression of rpoS, arcA, arcB, and invA genes was evaluated. After the inoculation of G. mellonella with the median lethal dose (LD) of Salmonella PT4, the survival of bacteria inside the larvae and their health status (health index scoring) were monitored, as well as the pigment, nitric oxide (NO), superoxide dismutase (SOD), and catalase (CAT) production. Also, the hemocyte viability, the induction of caspase-3, and microtubule-associated light chain 3 (LC3) protein in hemocytes were evaluated. Salmonella PT4 growing in the presence of C12-HSL showed increased rpoS, arcA, arcB, and invA expression and promoted higher larvae mortality and worse state of health after 24 h of infection. The C12-HSL also increased the persistence of Salmonella PT4 in the hemolymph and in the hemocytes. The highest pigmentation, NO production, and antioxidant enzymes were verified in the larva hemolymph infected with Salmonella PT4 grown with C12-HSL. Hemocytes from larvae infected with Salmonella PT4 grown with C12-HSL showed lower viability and higher production of caspase-3 and LC3. Taken together, these findings suggest that C12-HSL could be involved in the virulence of Salmonella PT4.
沙门氏菌是一种食源性和水源性病原体，可导致全球范围内的疫情爆发，它可以在通过胃部和宿主吞噬细胞时存活下来。感染和在巨噬细胞中存活需要毒力基因，其中一些受群体感应（QS）系统的调节。本研究使用家蚕作为感染模型，研究了自动诱导物 1（AI-1）、N-十二酰基高丝氨酸内酯（C12-HSL）对沙门氏菌 PT4 毒力的影响。在厌氧条件下，沙门氏菌 PT4 在存在和不存在 C12-HSL 的情况下培养 7 小时，评估 rpoS、arcA、arcB 和 invA 基因的表达。用沙门氏菌 PT4 的半数致死剂量（LD）接种家蚕后，监测细菌在幼虫体内的存活情况及其健康状况（健康指数评分），以及色素、一氧化氮（NO）、超氧化物歧化酶（SOD）和过氧化氢酶（CAT）的产生。此外，还评估了血细胞的活力、半胱天冬酶-3 的诱导以及血细胞中的微管相关轻链 3（LC3）蛋白。在 C12-HSL 存在下生长的沙门氏菌 PT4 表现出 rpoS、arcA、arcB 和 invA 表达增加，并在感染后 24 小时促进更高的幼虫死亡率和更差的健康状态。C12-HSL 还增加了沙门氏菌 PT4 在血淋巴和血细胞中的持久性。在感染 C12-HSL 培养的沙门氏菌 PT4 的幼虫血淋巴中，检测到最高的色素、NO 产生和抗氧化酶。感染 C12-HSL 培养的沙门氏菌 PT4 的幼虫血细胞显示出较低的活力和更高的半胱天冬酶-3 和 LC3 的产生。综上所述，这些发现表明 C12-HSL 可能参与了沙门氏菌 PT4 的毒力。
