■海洋水产养殖业目睹了世界性的龙杆菌病的出现,一种鲜为人知的细菌性疾病,由海生Tenacibaculumairtimum引起,影响商业上重要的鱼类。到目前为止,关于马氏T.maritimum毒力机制的知识很少,在tenacibacusis病中的病原体-宿主相互作用仍有待披露。这项研究旨在有助于更好地了解这种疾病,通过评估欧洲鲈鱼(Dicentrarchuslabrax)通过用T.maritimum进行沐浴挑战而触发的早期先天免疫反应。
■组的鲈鱼受到T.maritimum(挑战鱼)或模拟挑战。将未受干扰的鱼用作对照(时间0)。血液样本,肝脏和粘膜器官(皮肤,g和后肠)在攻击后0h(对照)和6、24、48和72h(n=12)收集。通过RT-qPCR分析黏膜器官免疫相关基因的表达,以及用于评估血液学和先天体液参数的血液样本和用于氧化应激评估的肝脏。
■IL-1β的表达增加,与对照和模拟攻击鱼相比,在感染鱼的所有粘膜器官中检测到il8,mmp9和hamp1,提示对所有器官都有抗马氏毛虫的促炎反应。在the中观察到这些促炎基因的更快诱导。关于系统性反应,受挑战的鱼出现嗜中性粒细胞增多症,单核细胞增多,贫血的迹象,血浆中杀菌和溶菌酶活性降低。关于肝氧化应激几乎没有观察到变化。
■目前的研究表明,马氏T.maritimum不仅在欧洲鲈鱼的皮肤上引起沐浴感染后的局部先天免疫反应,但也在ill和后肠,可能是由T.maritimum的坚持能力引发的,定殖和损伤这些可以作为细菌进入途径的器官,最终导致所见宿主的系统反应。
The marine aquaculture industry has been witnessing a worldwide emergence of
tenacibaculosis, a poorly understood bacterial disease caused by Tenacibaculum maritimum that affects commercially important fish. So far, knowledge on the T. maritimum virulence mechanisms is scarce and the pathogen-host interaction operating in
tenacibaculosis remain to be disclosed. This study aimed at contributing to a better understanding of this disease, by evaluating the early innate immune response triggered in European sea bass (Dicentrarchus labrax) by a bath-challenge with T. maritimum.
Groups of sea bass were bath-challenged with T. maritimum (challenged fish) or mock-challenged. Undisturbed fish were used as controls (time 0). Samples of blood, liver and mucosal organs (skin, gills and posterior-intestine) were collected at 0 h (control) and at 6, 24, 48 and 72 h post-challenge (n=12). Mucosal organs were used for analyzing the expression of immune-related genes by RT-qPCR, as well as blood samples for assessing haematological and innate humoral parameters and liver for oxidative stress assessment.
An increased expression of il-1β, il8, mmp9 and hamp1 was detected in all mucosal organs of infected fish when compared with control and mock-challenged fish, suggesting a pro-inflammatory response against T. maritimum transversal to all organs. The faster induction of these pro-inflammatory genes was observed in the gills. Regarding the systemic response, challenged fish presented neutrophilia, monocytosis, signs of anemia, and a decrease of bactericidal and lysozyme activities in plasma. Almost no variations were observed regarding hepatic oxidative stress.
The present study suggests that T. maritimum induces a local innate immune response upon bath infection not only in the skin of European sea bass, but also in the gills and posterior-intestine, likely triggered by the T. maritimum\'s capacity to adhere, colonize and damage these organs that can function as entry ways to bacteria, leading ultimately to the seen host\'s systemic response.