【背景】猪链球菌2型(streptococcus suis type 2, SS2)可引起人、猪的脑膜炎、关节炎及败血症等,不仅给养猪业带来巨大的经济损失,同时严重威胁公共卫生安全。本团队前期通过噬菌体展示文库技术发现Orf207编码蛋白可能参与SS2诱导的脑膜炎发生,然而其在SS2致病过程中的具体作用尚不清楚。【目的】探究Orf207基因对SS2致病性的影响。【方法】采用温敏性自杀质粒介导的同源重组系统,构建SC19 Orf207基因缺失菌株ΔOrf207及其回补菌株CΔOrf207,系统比较缺失菌株与野生株间在生长特性、形态、组织定殖能力、毒力情况、细胞黏附与侵袭及抗巨噬细胞吞噬能力等生物学特性方面的差异。【结果】与野生株相比,缺失菌株链长变短,生长速度略慢;而且Orf207缺失显著增加了小鼠的存活率,降低了细菌在血液、心脏、肝脏、脾脏、肺脏、肾脏、脑组织的定殖能力和对肺组织的病理损伤并显著减弱SS2对HeLa细胞的黏附与侵袭能力及抗巨噬细胞吞噬能力。【结论】Orf207基因可以显著降低SS2对宿主的致病能力,本研究结果不仅丰富了SS2的致病机制,也为SS2疫苗等研发提供了新靶点。 相似文献
Salinity impairs plant growth and development, thereby leading to low yield and inferior quality of crops. Nitric oxide (NO) has emerged as an essential signaling molecule that is involved in regulating various physiological and biochemical processes in plants. In this study, tomato seedlings of Lycopersicum esculentum L. “Micro-Tom” treated with 150 mM sodium chloride (NaCl) conducted decreased plant height, total root length, and leaf area by 25.43%, 24.87%, and 33.67%, respectively. While nitrosoglutathione (GSNO) pretreatment ameliorated salt toxicity in a dose-dependent manner and 10 µM GSNO exhibited the most significant mitigation effect. It increased the plant height, total root length, and leaf area of tomato seedlings, which was 31.44%, 20.56%, and 51.21% higher than NaCl treatment alone, respectively. However, NO scavenger 2-(4-carboxyphenyl)-4, 4, 5, 5-tetramethylimidazoline-1-oxyl-3-oxide potassium (cPTIO) treatment reversed the positive effect of NO under salt stress, implying that NO is essential for the enhancement of salt tolerance. Additionally, NaCl?+?GSNO treatment effectively decreased O2? production and H2O2 content, increased the levels of soluble sugar, glycinebetaine, proline, and chlorophyll, and enhanced the activities of antioxidant enzymes and the content of antioxidants in tomato seedlings in comparison with NaCl treatment, whereas NaCl?+?cPTIO treatment significantly reversed the effect of NO under salt stress. Moreover, we found that GSNO treatment increased endogenous NO content, S-nitrosoglutathione reductase (GSNOR) activity, GSNOR expression and total S-nitrosylated level, and decreased S-nitrosothiol (SNO) content under salt stress, implicating that S-nitrosylation might be involved in NO-enhanced salt tolerance in tomatoes. Altogether, these results suggest that NO confers salt tolerance in tomato seedlings probably by the promotion of photosynthesis and osmotic balance, the enhancement of antioxidant capability and the increase of protein S-nitrosylation levels.