左旋咪唑对中华绒螯蟹非特异性免疫功能及抗病力的影响

为测定在饲料中添加左旋咪唑(LMS)对中华绒螯蟹(Eriocheir sinensis)的免疫调节作用,以0(对照)、100、200和300 mg·kg~(-1)干饲料的剂量将LMS添加于基础饲料中制成颗粒饲料,投喂中华绒螯蟹7 d,然后投喂不含LMS的对照组饲料。在投喂含LMS的饲料之前(0周)和投喂后2、4、6、8周,采样测定中华绒螯蟹的血细胞总量(THC)、不同血细胞数量(DHC)、吞噬活性、呼吸爆发(超氧阴离子的释放)、酚氧化酶(PO)活性和溶菌酶(LSZ)活性;并在投喂含LMS的饲料后的第4周,按1.2×10~7cfu·kg~(-1)体重的剂量,体腔注射接种中华绒螯蟹致病性嗜水气单胞菌(Aeromonas hyrophila)CL99920菌株,记录接种10d后中华绒螯蟹的累积死亡率。结果显示,各LMS处理组的血细胞总量(THC)、透明细胞(HC)数量、吞噬百分率、呼吸爆发、PO活性和LSZ活性均显著地高于对照组(P<0.05);颗粒细胞(GC)数量、血细胞吞噬指数与对照组无显著差异(P>0.05);LMS处理组的蟹对嗜水气单胞菌的抵抗力明显增强。研究表明,饲喂适量的LMS可增强中华绒螯蟹的免疫力和抗病力;在本试验条件下,200 mg·kg~(-1)干饲料的剂量为最适添加剂量。

Effects of levamisole on the non-specific immune response and disease resistance of Chinese mitten crab Eriocheir sinensis

Abstract: In order to determine the immunomodulatory effect of the dietary intake of levamisole in the Chinese mitten crab (Eriocheir sinensis), the crab were fed diets containing 0 (control), 100, 200 and 300 mg levamisole kg−1 dry diet for 7 days. The total haemocyte count (THC), differential haemocyte count (DHC), phagocytic activity, respiratory burst (release of superoxide anion), phenoloxidase (PO) activity and lysozyme (LSZ) activity were examined at 0, 2, 4, 6, and 8 weeks after administration of levamisole. Crab were challenged at 1.2 × 107 colony forming units (cfu) kg−1 crab weight with a virulent strain of Aeromonas hydrophila (CL99920) of E. sinensis at 4 weeks after administration of levamisole, and mortalities were recorded over a 10-day period. The results demonstrate that crab treated with levamisole showed significantly higher THC, the amount of hyaline cells (HC), phagocytic percentage (PP), respiratory burst (release of superoxide anion), PO activity and LSZ activity than those of the control group (P<0.05). No significant differences in the amount of granular cells (GC) and phagocytic index (PI) of haemocyte among the crab fed with diets containing 0 (control) and those fed with diets at 100, 200 or 300 mg levamisole kg−1 dry die (P>0.05). Furthermore, the levamisole treated E. sinensis were the more resistant. It was concluded that E. sinensis that were fed with diets at 100, 200 or 300 mg levamisole kg−1 dry die showed increased immune ability as well as resistance to A. hydrophila infection. Under the experimental condition, the optimum dose of dietary intake of levamisole should be 200 mg levamisole kg−1 dry diet. Keywords: Eriocheir sinensis; levamisole; immune response; disease resistance; Aeromonas hydrophila