Institute of Science and Technology in Medicine, School of Life Sciences, Keele University, ST5 5BG Keele, United Kingdom.
Fish Shellfish Immunol. 2013 Mar;34(3):819-31. doi: 10.1016/j.fsi.2012.12.017. Epub 2013 Jan 2.
The effect of β-glucans as feed additive on the profile of C-reactive protein (CRP) and complement acute phase responses was studied in common carp Cyprinus carpio after exposition to a bacterial infection with Aeromonas salmonicida. Carp were orally administered with β-glucan (MacroGard®) for 14 days with a daily β-glucan intake of 6 mg per kg body weight. Fish were then intraperitoneally injected with either PBS or 1 × 10⁸ bacteria per fish and sampled at time 0, 6, 12, 24, 48, 72, 96 and 120 h post-injection (p.i.) for serum and head kidney, liver and mid-gut tissues. CRP levels and complement activity were determined in the serum samples whilst the gene expression profiles of CRP and complement related genes (crp1, crp2, c1r/s, bf/c2, c3 and masp2) were analysed in the tissues by quantitative PCR. Results obtained showed that oral administration of β-glucan for 14 days significantly increased serum CRP levels up to 2 fold and serum alternative complement activity (ACP) up to 35 fold. The bacterial infection on its own (i.e. not combined with a β-glucan feeding) did have significant effects on complement response whilst CRP was not detectably induced during the carp acute phase reaction. However, the combination of the infection and the β-glucan feeding did show significant effects on both CRP and complement profiles with higher serum CRP levels and serum ACP activity in the β-glucan fed fish than in the control fed fish. In addition, a distinct organ and time dependent expression profile pattern was detected for all the selected genes: a peak of gene expression first occurred in the head kidney tissue (6 h p.i. or 12 h p.i.), then an up-regulation in the liver several hours later (24 h p.i.) and finally up- or down-regulations in the mid-gut at 24 h p.i. and 72 h p.i. In conclusion, the results of this study suggest that MacroGard® stimulated CRP and complement responses to A. salmonicida infection in common carp.
β-葡聚糖作为饲料添加剂对鲤鱼（Cyprinus carpio）在受到嗜水气单胞菌感染后的 C 反应蛋白（CRP）和补体急性期反应谱的影响进行了研究。鲤鱼经口给予β-葡聚糖（MacroGard®）14 天，每天每公斤体重摄入 6 毫克β-葡聚糖。然后，鱼被腹膜内注射 PBS 或每鱼 1×108 个细菌，并在注射后 0、6、12、24、48、72、96 和 120 小时取样，用于血清和头肾、肝和中肠组织。在血清样本中测定 CRP 水平和补体活性，同时通过定量 PCR 分析组织中 CRP 和补体相关基因（crp1、crp2、c1r/s、bf/c2、c3 和 masp2）的基因表达谱。结果表明，连续 14 天口服β-葡聚糖可使血清 CRP 水平增加 2 倍，血清替代补体活性（ACP）增加 35 倍。单独的细菌感染（即未与β-葡聚糖喂养结合）对补体反应有显著影响，而 CRP 在鲤鱼急性期反应中未被检测到诱导。然而，感染和β-葡聚糖喂养的结合对 CRP 和补体谱都有显著影响，与对照组相比，β-葡聚糖喂养的鱼血清 CRP 水平和血清 ACP 活性更高。此外，所有选定基因的表达谱都呈现出明显的器官和时间依赖性：首先在头肾组织中出现基因表达峰值（感染后 6 小时或 12 小时），然后在数小时后肝脏中上调（24 小时），最后在中肠中上调或下调（24 小时和 72 小时）。总之，这项研究的结果表明，MacroGard®刺激了鲤鱼对嗜水气单胞菌感染的 CRP 和补体反应。
