Alternative prophylactic strategies to limit farm animal infection are needed in order to avoid the use of antibiotics. Anti-bacterial and immunostimulatory properties of bioactive compounds are of great interest in aquaculture. Marine derived polysaccharides, such as chitosan and ulvan, together with nanotechnology, have become the focus of attention in the scientific community due to their wide range of biological properties. In this work, chitosan and ulvan-loaded chitosan nanoparticles (referred as CS-TPP NPs and CS-UL-TPP NPs, respectively), obtained by the ionotropic gelation method, had round shape, and the mean sizes were 137.00 ± 5.44 and 325.50 ± 4.95 nm, respectively. No study about the anti-bacterial activity of both types of NPs against Photobacterium damselae subsp. piscicida, an important fish pathogen, has been reported so far. Furthermore, the potential immunostimulatory effects of CS-UL-TPP NPs after oral administration in fish have not yet been evaluated. The percentage of bacterial inhibition against P. damselae subsp. piscicida was determined through in vitro assays, and it was significantly higher in CS-UL-TPP NPs than in CS-TPP NPs at concentrations below 0.03 mg mL⁻¹. The effects on the immune system of CS-TPP and CS-UL-TPP NPs were evaluated in Solea senegalensis juveniles at 30 days after oral administration. Lysozyme activity as well as gene expression levels of il1b, il6, hamp1, tf and c3 was significantly higher in CS-UL-TPP NP-treated groups than in the controls, and no significant differences were observed in CS-TPP NP-treated groups. Thus, ulvan extracted from the macroalgae Ulva ohnoi could improve anti-bacterial and immunostimulant properties of CS-TPP NPs thereby making them suitable to be used as vaccine adjuvant or as immunostimulant.

需要采取替代预防策略来限制农场动物感染，以避免使用抗生素。生物活性化合物的抗菌和免疫刺激特性在水产养殖中引起了极大的兴趣。海洋来源的多糖，如壳聚糖和绿藻硫化多糖，与纳米技术一起，由于其广泛的生物特性而成为科学界关注的焦点。本研究通过离子凝胶法制备得到的壳聚糖和绿藻硫化多糖纳米粒子（分别称为CS-TPP NPs和CS-UL-TPP NPs）呈圆形，平均粒径分别为137.00±5.44和325.50分别为 ± 4.95 nm。尚无关于两类纳米粒子对Photobacter damselae亚种的抗菌活性的研究。 piscicida是一种重要的鱼类病原体，目前已有报道。此外，CS-UL-TPP NPs 口服给药后对鱼类的潜在免疫刺激作用尚未得到评估。对P的细菌抑制百分比。 damselae 亚种。 杀鱼类通过体外测定进行测定，在浓度低于 0.03 mg mL 时，CS-UL-TPP NP 中的杀鱼类显着高于 CS-TPP NP ⁻¹。口服给药 30 天后，在Solea senegalensis幼鱼中评估了 CS-TPP 和 CS-UL-TPP NP 对免疫系统的影响。溶菌酶活性以及il1b、il6、<的基因表达水平/span>c3< CS-UL-TPP NP处理组中的/span>中提取的绿藻硫化多糖可以提高CS-TPP NPs的抗菌和免疫刺激特性，从而使其适合用作疫苗佐剂或作为免疫刺激剂。Ulva ohnoi显着高于对照组，并且在CS-TPP NP处理组中没有观察到显着差异。因此，从大型藻类 和 tf、hamp1