Mannan oligosaccharides (MOS) have shown to stimulate immune response in different fish species, but the results may appear contradictory and have not been tested in conjunction with vaccination. We hypothesized that dietary MOS supplementation could enhance efficacy and immune responses after immunization with a novel hydrogen peroxide-inactivated vaccine. Nile Tilapia, Oreochromis niloticus, fingerlings were distributed into four groups (supplemented or not, vaccinated or not) and were used to determine immune and hematological parameters and somatic indexes. For the bacterial challenge and vaccine efficacy test, fish were assigned to five experimental groups. Twenty-eight days after the feeding trial and vaccination, the groups were challenged intraperitoneally and monitored for 21 days. The relative percent survival of the groups basal diet-vaccinated and MOS diet-vaccinated were 98.1% and 100.0%, respectively. The dietary inclusion of MOS after vaccination for 28 days had no influence on vaccine efficacy, which could be explained because of the high efficacy of the vaccine itself. Therefore, we suggest that the contribution of MOS supplementation to immune responses after vaccination in fish would be greater for vaccines with lower efficacy, or when tested for heterologous challenges or for crossed protection.

中文翻译：

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日粮中添加甘露寡糖对尼罗罗非鱼新型无乳链球菌灭活疫苗功效的影响

甘露寡糖 (MOS) 已被证明可以刺激不同鱼类的免疫反应，但结果可能看似矛盾，并且尚未与疫苗接种一起进行测试。我们假设膳食 MOS 补充剂可以增强新型过氧化氢灭活疫苗免疫后的功效和免疫反应。将尼罗罗非鱼、尼罗罗非鱼、鱼种分为四组（补充或未补充、接种或未接种），用于测定免疫和血液学参数以及体细胞指标。对于细菌攻击和疫苗功效测试，鱼被分配到五个实验组。喂养试验和疫苗接种后 28 天，对各组进行腹膜内攻击并监测 21 天。基础饮食接种组和MOS饮食接种组的相对存活率分别为98.1%和100.0%。接种疫苗28天后饮食中添加MOS对疫苗功效没有影响，这可以解释为疫苗本身的高效性。因此，我们建议，对于功效较低的疫苗，或者在进行异源攻击或交叉保护测试时，补充 MOS 对鱼类接种疫苗后的免疫反应的贡献会更大。