Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, PR China.
Department of Basic Veterinary, College of Veterinary Medicine, Sichuan Agricultural University, Chengdu, Sichuan, PR China; Key Laboratory of Animal Disease and Human Health of Sichuan Province, Sichuan Agricultural University, Chengdu, Sichuan, PR China.
Fish Shellfish Immunol. 2019 Apr;87:155-165. doi: 10.1016/j.fsi.2019.01.007. Epub 2019 Jan 8.
Channel catfish is one of the most extensively cultured species worldwide, which is widely used as a classical model for comparative immunology. Interleukin-1β (IL1β) is an immunoregulatory cytokine with the potential to enhance the immune response induced by vaccines in many animals. To characterize the molecular characterization and identify the immunoadjuvant role of channel catfish IL1β, molecular cloning, phylogenetic analysis, and expression of two IL1β genes were performed, the bioactivity of their recombinant proteins (rIL1β1 and rIL1β2) were detected in vitro and their adjuvant effects on a subunit vaccine encoding C5a peptidase (pSCPI) of Streptococcus iniae were evaluated. The results indicated that two IL1βs remained highly conserved possessing five conserved motifs compared with other fish IL1βs, although there were 28 nucleotide differences and 16 amino acid differences between channel catfish IL1β1 and IL1β2. Analysis of the ratios of nonsynonymous (dN) and synonymous (dS) substitutions revealed that fish IL1β genes were subjected to negative/purifying selection with global dN/dS ratios value 0.425. The results of adjuvant effect showed that compared with injection of pSCPI alone, co-injecting pSCPI with both rIL1β1 and rIL1β2 significantly enhanced antibody levels, serum bactericidal activity, lysozyme activity, alternative complement hemolytic activity, and the expression of endogenous IL1β and TNF-α in head kidney and spleen. Although vaccination with rIL1β1 or rIL1β2 failed to offer immunoprotection against S. iniae infection, the RPS (relative percent survival) of pSCPI+rIL1β1 and pSCPI+rIL1β2 groups were both higher than pSCPI alone (RPS, 50%), with 64.26% and 60.71%, respectively. Moreover, pSCPI+rIL1β1+rIL1β2 offered significantly higher (P < 0.05) immunoprotection (RPS, 75%) against S. iniae infection than pSCPI alone. Our present results not only enrich the molecular structure study of fish IL1βs but also signify that two recombinant channel catfish IL1βs can be used as potential adjuvants in a subunit vaccine model against bacterial infection, which are of profound importance to prevent and control bacterial disease in channel catfish.
斑点叉尾鮰是全球养殖最广泛的品种之一，广泛用作比较免疫学的经典模式生物。白细胞介素-1β（IL1β）是一种具有免疫调节作用的细胞因子，能够增强许多动物疫苗诱导的免疫反应。为了研究斑点叉尾鮰 IL1β 的分子特征和鉴定其免疫佐剂作用，我们进行了分子克隆、系统进化分析和两个 IL1β 基因的表达，检测了其重组蛋白（rIL1β1 和 rIL1β2）的体外生物活性，并评估了它们对编码鳗弧菌 C5a 肽酶（pSCPI）的亚单位疫苗的佐剂效应。结果表明，尽管斑点叉尾鮰 IL1β1 和 IL1β2 之间存在 28 个核苷酸差异和 16 个氨基酸差异，但与其他鱼类的 IL1β 相比，两种 IL1β 仍高度保守，具有五个保守基序。与其他鱼类的 IL1β 相比，两种 IL1β 仍高度保守，具有五个保守基序。与其他鱼类的 IL1β 相比，两种 IL1β 仍高度保守，具有五个保守基序。与其他鱼类的 IL1β 相比，两种 IL1β 仍高度保守，具有五个保守基序。与其他鱼类的 IL1β 相比，两种 IL1β 仍高度保守，具有五个保守基序。与其他鱼类的 IL1β 相比，两种 IL1β 仍高度保守，具有五个保守基序。尽管鱼类 IL1β 基因的全球 dN/dS 比值为 0.425，表明它们受到了负/纯化选择，但分析表明，鱼类 IL1β 基因受到了负/纯化选择。佐剂效应的结果表明，与单独注射 pSCPI 相比，同时注射 pSCPI 与 rIL1β1 和 rIL1β2 显著提高了抗体水平、血清杀菌活性、溶菌酶活性、替代补体溶血活性以及头肾和脾脏中内源性 IL1β 和 TNF-α的表达。尽管单独接种 rIL1β1 或 rIL1β2 不能提供对鳗弧菌感染的免疫保护，但 pSCPI+rIL1β1 和 pSCPI+rIL1β2 组的相对存活率（RPS）均高于单独接种 pSCPI 的组（RPS，50%），分别为 64.26%和 60.71%。此外，pSCPI+rIL1β1+rIL1β2 对鳗弧菌感染的免疫保护作用显著高于单独接种 pSCPI 的组（RPS，75%）。我们的研究结果不仅丰富了鱼类 IL1β 的分子结构研究，还表明两种重组斑点叉尾鮰 IL1β 可用作细菌感染亚单位疫苗的潜在佐剂，这对于预防和控制斑点叉尾鮰的细菌性疾病具有重要意义。
