Abstract：
The interleukin-17 (IL-17) family of cytokines is critical for host defense responses and mediates different pro- or anti-inflammatory mediators through different signaling pathways. However, the function of the related family member, IL-17B, in teleosts is poorly understood. In the present study, an IL-17B homolog (CcIL-17B) in common carp (Cyprinus carpio) was identified, and sequence analysis showed that CcIL-17B had eight conserved cysteine residues, four of which could form two pairs of disulfide bonds, which in turn formed a ring structure composed of nine amino acids (aa). The deduced aa sequences of CcIL-17B shared 35.79-92.93 % identify with known homologs. The expression patterns were characterized in healthy and bacteria-infected carp. In healthy carp, IL-17B mRNA was highly expressed in the spleen, whereas Aeromonas veronii effectively induced CcIL-17B expression in the liver, head, kidney, gills, and intestine. The recombinant protein rCcIL-17B could regulate the expression levels of inflammatory cytokines (such as IL-1β, IL-6, TNF-α, and IFN-γ) in primary cultured head kidney leukocytes in vitro. As an adjuvant for the formalin-killed A. veronii (FKA) vaccine, rCcIL-17B induced the production of specific antibodies more rapidly and effectively than Freund\'s complete adjuvant (FCA). The results of the challenge experiments showed that the relative percent survival (RPS) after vaccination with rCcIL-17B was 78.13 %. This percentage was significantly elevated compared to that observed in the alternative experimental groups (62.5 % and 37.5 %, respectively). Additionally, the bacterial loads in the spleen of the rCcIL-17B + FKA group were significantly lower than those in the control group from 12 h to 48 h after bacterial infection. Furthermore, histological analysis showed that the epithelial cells were largely intact, and the striated border structure was complete in the intestine of rCcIL-17B + FKA group. Collectively, our results demonstrate that CcIL-17B plays a crucial role in eliciting immune responses and evokes a higher RPS against A. veronii challenge compared to the traditional adjuvant FCA, indicating that rCcIL-17B is a promising vaccine adjuvant for controlling A. veronii infection.
摘要：
细胞因子的白细胞介素-17(IL-17)家族对于宿主防御反应至关重要,并且通过不同的信号传导途径介导不同的促炎或抗炎介质。然而,相关家庭成员的功能，IL-17B,在硬骨鱼中知之甚少。在本研究中,鉴定了鲤鱼（鲤鱼）中的IL-17B同源物（CcIL-17B），序列分析表明CcIL-17B有8个保守的半胱氨酸残基,其中四个可以形成两对二硫键，进而形成由9个氨基酸(aa)组成的环状结构。CcIL-17B的推导的aa序列与已知同源物共有35.79-92.93％的同一性。在健康和细菌感染的鲤鱼中表征了表达模式。在健康的鲤鱼中，IL-17BmRNA在脾脏中高表达,而Veronii气单胞菌有效诱导CcIL-17B在肝脏中的表达，头部,肾,ill,和肠。重组蛋白rCcIL-17B可以调节炎性细胞因子(如IL-1β,IL-6,TNF-α,和IFN-γ）在体外原代培养的头肾白细胞中。作为福尔马林杀死的A.veronii（FKA）疫苗的佐剂，rCcIL-17B比弗氏完全佐剂(FCA)更快速和有效地诱导特异性抗体的产生。攻击实验的结果显示,用rCcIL-17B接种后的相对存活百分比(RPS)为78.13%。与替代实验组相比，该百分比显着升高（62.5％和37.5％，分别)。此外,细菌感染后12h至48h，rCcIL-17BFKA组脾脏中的细菌负荷显着低于对照组。此外，组织学分析显示上皮细胞基本完整,rCcIL-17B+FKA组肠横纹边界结构完整。总的来说，我们的结果表明，与传统的佐剂FCA相比，CcIL-17B在引发免疫反应中起着至关重要的作用，并引起更高的RPS，这表明rCcIL-17B是一种有前途的疫苗佐剂，用于控制veronii感染。
