創傷弧菌屬於嗜鹽性的格蘭氏陰性菌，常分布於熱帶及亞熱帶的海洋中。人類遭創傷弧菌感染後的發病速度快且毒性猛烈，病患常在送醫後的48小時內死亡。創傷弧菌感染會引發原發性敗血症，主要是經由生食未煮熟的海鮮所引起，其症狀為發熱、休克及皮膚病變，其致死率為50%；經由傷口感染所導致的次發性敗血症則會引發蜂窩性組織炎，其致死率為25%。先前實驗室經由細胞的毒性分析選殖出一段可使創傷弧菌毒性下降的基因argD，經序列分析後發現argD基因與菌體合成精胺酸有關。因此，本論文主要探討argD基因對創傷弧菌感染的影響。在細胞毒殺試驗中，創傷弧菌argD基因缺失後會降低菌體對巨噬細胞的毒性。在養分限制的培養基發現，創傷弧菌argD基因可使菌體在精胺酸限制的環境中生長。在菌體抗過氧化氫的實驗顯示，argD缺失的創傷弧菌在過氧化氫的環境中存活率較低。在小鼠存活率的實驗中，缺乏argD基因的創傷弧菌會使小鼠的存活率增加。由以上的結果可得知，argD基因會影響創傷弧菌的生長及抗過氧化氫的能力，所以argD基因在創傷弧菌的感染中扮演著重要的角色。 Vibrio vulnificus is a halophilic Gram-negative bacterium and always occurs in tropical and subtropical oceans. The bacteria can result in a serious, fulminant infection. Therefore, patients are dead within 2 days after hospitalization. V. vulnificus infection can cause primary septicemia via eating raw seafood with fever, shock and skin lesions, with the fatality rate about 50%. Wound infection can cause secondary septicemia and cellulitis, with the fatality rate about 25%.In our previous study, we found argD gene has cytotoxicity to macrophage, and its function was related to arginine synthesis from sequence analysis. Therefore, in this study, we focus on the influence of argD gene in V. vulnificus infection. Analysis of cytotoxicity, argD mutant had lower virulence to macrophage than the wild type and argD-complemented strains. The argD gene showed increased growth under arginine-limited conditions. In H2O2 resistance assay, argD mutant showed decreased resistance to H2O2. The intracellular survival rate of argD mutant inside macrophages also was lower than those of wild type and argD-complemented strains. In mouse experiment, argD mutant displayed reduced virulence. In conclusion, argD plays an important role in V. vulnificus infection.
