布鲁氏菌M5-90△WboA基因缺失株的构建及免疫效果的初步评价

摘要

Vaccination is a major measure for prevention of brucellosis, but it is unable to be distinguished from the vaccinated to natural infected animals. In this study, the WboA gene was knocked out of the genomic DNA of Brucelh melitensis vaccine M5-90 strain to construct the recombinant M5-90 A WboA by homologous recombination. The test results showed that M5-90 A WboA was less virulent than that of the parent M5-90 strain (p<0.01). Humoral immunity and cellular immunity tests showed that there was no significant difference between M5-90A WboA and M5-90 parent strain (p<0.05). BALB/c mice were immunized with M5-90 A WboA or M5-90 and challenged with virulent strain 16M and the survival rate were 10% and 20%, respectively, indicating that the M5-90 A WboA provided the similar protection of M5-90 strain. Agglutination test and western blot showed that the serum response of M5-90 △ WboA in vaccinated mice were negative. These results indicated that M5-90 A WboA strain might be a promising vaccine against brucellosis, and could be distinguished from the vaccine immunization to natural infection in animals by serum test.%为获得毒力较弱并能区分自然感染和疫苗免疫的布鲁氏菌候选疫苗株,本研究用PCR方法扩增WboA基因的上下游同源臂序列,构建重组质粒pGEM-7zf-△WboA-Sac,电转化布鲁氏菌M5-90感受态细胞,筛选布鲁氏菌疫苗株M5-90的WboA基因缺失株,并对获得的M5-90△WboA遗传稳定性、毒力、免疫保护性、抗体水平等指标进行检测.实验结果表明M5-90△WboA株的毒力比M5-90株明显减弱,差异极显著(p＜0.01),体液免疫和细胞免疫结果表明M5-90△WboA株与亲本M5-90株相比差异不显著(p＜0.05),M5-90△WboA株和亲本株的保护率分别为10％和20％,表明M5-90△WboA株与M5-90株具有相似的保护性.凝集试验和western blot试验显示M5-90△WboA株免疫小鼠的血清反应结果为阴性.本研究构建的布鲁氏菌基因缺失株M5-90△WboA具有较好的遗传稳定性,毒力比亲本株更弱,免疫保护性与亲本株相当,并能以血清学检测方法区分野毒株感染和缺失疫苗株免疫的动物.