口服嗜水气单胞菌生物被膜疫苗的动物免疫试验

Evaluation of biofilm of Aeromonas hydrophila for oral vaccination

将热灭活的嗜水气单胞菌(Aeromonashydrophila)生物被膜(biofilm,BF)菌苗和浮游(freecell,FC)菌苗口服免疫小鼠和剑尾鱼,通过测定抗体效价、相对保护率、小鼠的淋巴细胞转化和肠道sIgA浓度,评价免疫效果。免疫20d后,BF菌苗组50尾剑尾鱼的相对保护率为68%;FC菌苗组为42%。BF菌苗组12只小鼠的相对保护率为70%;FC菌苗组为50%;对照组为17%。BF菌苗组小鼠外周血淋巴细胞转化率是7.28、FC菌苗组为3.87、对照组为2.36。BF菌苗组小鼠肠道sIgA浓度是1.22μg/mL;FC菌苗组为0.73μg/mL;对照组为0.465μg/mL。免疫30d后,小鼠的血清凝集抗体达到最高,BF组抗体达128:1,FC组为32:1,对照组为2:1。各组间差异显著(P<0.01)。结果表明,BF菌苗较FC菌苗能更有效地刺激机体的免疫系统,尤其是肠道淋巴组织的免疫应答,对剑尾鱼和小鼠具有较好的保护力。

Among the various methods of vaccination, the oral routs is simple, cheap and ideal for mass administration to fish of all size. However, attempts to orally vaccinate against motile aeromonad septicemia have either yielded mild and short lived or inadequate responses. One of the important factors for the inconsistency and poor response to oral vaccination is the digestive degradation of antigens in the foregut before the vaccine reaches immume-responsive areas in the hind-gut and other lymphoid organs. Certain bacteria form biofilm on substrates and these have been found to be resistant to antibiotics, phagocytosis and the killing effect of whole blood and serum due to a protective glycocalyx layer. The glycocalyx matrix of the biofilm vaccine is believed to protect the antigens against gastric destruction. Here we present further studies on the effection of dose and duration of oral vaccination with a biofilm vaccine of Aeromonas hydrophila in mice and swordtail fish. 150 mice and 66 swordtail fish (Xiphophorus helleri) were fed with the A.hydrophila J-1 biofilm(BF)and free cell(FC) vaccines inactivated by heat, which were mixed with ingredients of feed. Relative percentage survival(RPS), antibody titres, transformation of blood lymphocyte and sIgA secretion intestines in mouse were tested 20 days after vaccination, for 50 swordtail fish, RPS in BF and FC vaccine group were 68% and 42% respectively. For 12 mice, they were 70% and 50%. RPS in control group was 17%.In mice, the lymphocyte transformation rates in BF, FC vaccine group and the control group were 7.28, 3.87 and 2.36 respectively. The sIgA concentrations in intestinal fluid were 1.22 μg/mL, 0.73 μg/mL and 0.465 μg/mL individually. There were significant differences between the groups(P<0.01). It was obtained that the BF vaccine could enhance the immunological response of fish and mice,especially the gut-associated lymphoid tissue.