融合蛋白VP4-STI的免疫效果观察

研究显示，肠毒素是ETEC致幼畜腹泻的根本原因，由ETEC产生的肠毒素包括热敏感肠毒素（LT）和热稳定肠毒素（ST），其中ST又包括STI和STII。调查表明，几乎所有的腹泻幼畜只要分离到ETEC大部分都产生STI，但是，由于STI的分子量太小，几乎没有免疫原性，因此，通过基因融合的方式借助大分子物质提高STI的免疫原性是当前国内外学者致力于ETEC疫苗开发的重点。

Observation of the Immune Effect of Fusion Protein VP4-STI

The aim of the study was to investigate the immune effect of fusion protein VP4-STI.40 mouse were randomly divided into 4 groups of test bacterin group(30 μg VP4-STI 0.6 μg LTB),aluminiumhydroxide vaccine group(30 μg VP4-STI Al(OH)3 gel),pure protein VP4-STI vaccine group (30 μ VP4-STI)and PBS control group were immunized by rhinal dripping. And then,the antibody levels of the mouse were determined.The protection effects of mouse in all immmune groups were observed after the toxicity test with strong virulent strain C83902 of E. coli. Anti-VP4-STI antibodies were produeed in other groups with the highest at the 6th week,except PBS control group.The antibody level in aluminiumhydroxide bacterin group was higher than that in test vaccine group. The antibody level in pure protein VP4-STI baeterin group was lower,being extremely significantly different from that in test vaccine group(P＜0.001).Mouse in test vaccine group and aluminiam hydroxide baeterin group had better immuno-proteetion effect on strong virulent strain C83902 of E. coli.obviously different from that in PBS control group. The research provided basis for further improving the immunogenetieity of STI.