Probiotics can be used to reduce disease outbreaks in aquaculture. Some of them are characterised by their antagonistic activity against pathogens or the stimulation of the fish immune response, including the production of specific antibodies. If a probiotic has common antigens with a determined pathogen, it could produce antibodies with a cross-reaction to that pathogen. Thus, a probiotic with these characteristics could be used in a similar way to a live vaccine. The aim of this study was to select bacteria with antigenic similarity and antagonistic activity against the pathogens Photobacterium damselae subsp. piscicida and Vibrio harveyi, and to determine their ability to stimulate the production of antibodies in sole (Solea senegalensis, Kaup) with cross-reaction against these pathogens.

Dot blot was used to detect strains with cross-reaction using sera immunized against P. damselae subsp. piscicida Lg41.01 and V. harveyi Lg16.00. A total of 138 strains were selected from 718 strains, based on the intensity of the dot blot reaction. A second selection was performed to detect their ability to inhibit the pathogens growth. Five strains inhibited the growth of P. damselae subsp. piscicida, four strains inhibited the growth of V. harveyi, while two strains inhibited both pathogens. A Western blot confirmed the cross-reactions of the selected strains with the pathogens.

Selected strains were subsequently inoculated into sole specimens by intraperitoneal injection. Four strains produced antibodies with cross-reaction against the pathogens. None mortality was observed in the inoculated fish. Further research demonstrated the storage capability of the selected strains in saline solution and feed, their growth at low pH, and identified their enzymatic characteristics. In conclusion, the selected strains showed antimicrobial activity and capacity to activate a specific immune response against fish pathogens.

益生菌可用于减少水产养殖中的疾病暴发。它们中的一些以对病原体的拮抗活性或刺激鱼类的免疫反应为特征，包括产生特异性抗体。如果益生菌具有确定病原体的常见抗原，则可能会产生与该病原体交叉反应的抗体。因此，具有这些特征的益生菌可以类似于活疫苗的方式使用。这项研究的目的是选择对病原菌光子细菌亚种具有抗原相似性和拮抗活性的细菌。piscicida和哈维弧菌（Vibrio harveyi），并确定它们刺激唯一的抗体产生的能力（Solea senegalensis， Kaup）与这些病原体发生交叉反应。

使用斑点免疫法（D. damselae subsp。）免疫血清，使用斑点印迹法检测具有交叉反应的菌株。piscicida Lg41.01和V. harveyi Lg16.00。基于斑点印迹反应的强度，从718个菌株中选择了总共138个菌株。进行第二次选择以检测其抑制病原体生长的能力。五株抑制P. damselae亚种的生长。piscicida，四种菌株抑制哈维氏弧菌的生长，而两种菌株抑制两种病原体。Western印迹证实了所选菌株与病原体的交叉反应。

随后通过腹膜内注射将选定的菌株接种到唯一的样本中。四种菌株产生对病原体具有交叉反应的抗体。在接种的鱼中没有观察到死亡率。进一步的研究证明了所选菌株在盐溶液和饲料中的储存能力，它们在低pH下的生长，并确定了它们的酶促特性。总之，所选菌株显示出抗菌活性和激活针对鱼类病原体的特异性免疫反应的能力。