Selvaraj V, Sampath K, Sekar Vaithilingam
Spic Research and Development, Spic Limited, Tuticorin 628005, Tamil Nadu, India.
Vet Immunol Immunopathol. 2006 Nov 15;114(1-2):15-24. doi: 10.1016/j.vetimm.2006.06.011. Epub 2006 Aug 17.
Combined effects of beta-glucan and lipopolysaccharide (LPS) on survival and immune response were studied in Cyprinus carpio that were challenged with the pathogen Aeromonas hydrophila. beta-Glucan from Saccharomyces cervisiae and LPS from a virulent strain of A. hydrophila were used in this study. Different concentrations of beta-glucan+LPS mixture were administered on days 1, 7, and 14 through different routes (intraperitoneal injection, bathing, and oral administration). Control and test fish were challenged by intraperitoneal injection of LD50 concentration of A. hydrophila on day 16 and subsequently, mortality and relative percent survival (RPS) were recorded. Intraperitoneal injection elicited 100% RPS even at the lowest concentration (100 microg beta-glucan+10 microg LPS); whereas, oral administration improved RPS rate of carps at higher concentration (1% beta-glucan+0.25% LPS). Bathing did not improve the RPS. Test animals injected with even the minimum dose of the immunomodulators (100 microg beta-glucan+10 microg LPS/fish) had a significant increase in total blood leukocyte counts and an increase in the proportion of neutrophils and monocytes. Superoxide anion production by macrophages was also elevated, which presumably aided the efficient killing of bacterial pathogen. Lower concentration of beta-glucan+LPS had an adjuvant effect on antibody production as pretreatment by injection of 100 microg beta-glucan+10 microg LPS/fish resulted in higher antibody titer against A. hydrophila following vaccination. RT-PCR analyses showed that the expression of interleukin-1beta mRNA did not increase in test fish when compared with the control. Classical and alternative complement pathways were not affected by either the dose or the route of administration of the compounds. It may be concluded that intraperitoneal injection and oral administration, and not the bathing, of beta-glucan+LPS mixture in carp could enhance resistance to challenge by A. hydrophila through changes in several non-specific and specific immune responses.
研究了β-葡聚糖和脂多糖（LPS）联合作用对受嗜水气单胞菌病原体攻击的鲤鱼存活和免疫反应的影响。本研究使用了来自酿酒酵母的β-葡聚糖和来自嗜水气单胞菌强毒株的LPS。在第1、7和14天通过不同途径（腹腔注射、浸浴和口服）给予不同浓度的β-葡聚糖+LPS混合物。在第16天，通过腹腔注射LD50浓度的嗜水气单胞菌对对照鱼和试验鱼进行攻击，随后记录死亡率和相对存活率（RPS）。腹腔注射即使在最低浓度（100微克β-葡聚糖+10微克LPS）时也能引发100%的RPS；而口服给药在较高浓度（1%β-葡聚糖+0.25%LPS）时可提高鲤鱼的RPS率。浸浴并未提高RPS。即使注射最低剂量免疫调节剂（100微克β-葡聚糖+10微克LPS/鱼）的试验动物，其全血白细胞总数也显著增加，中性粒细胞和单核细胞比例升高。巨噬细胞产生超氧阴离子也有所增加，这可能有助于有效杀灭细菌病原体。较低浓度的β-葡聚糖+LPS对抗体产生有佐剂作用，因为通过注射100微克β-葡聚糖+10微克LPS/鱼进行预处理，在接种疫苗后导致针对嗜水气单胞菌的抗体滴度更高。RT-PCR分析表明，与对照相比，试验鱼中白细胞介素-1βmRNA的表达没有增加。经典和替代补体途径均不受化合物剂量或给药途径的影响。可以得出结论，在鲤鱼中腹腔注射和口服β-葡聚糖+LPS混合物，而非浸浴，可通过改变几种非特异性和特异性免疫反应来增强对嗜水气单胞菌攻击的抵抗力。
