空肠弯曲菌全菌灭活疫苗免疫鸡效果评价

Evaluation of the immune efficacy of inactivated whole-cell Campylobacter jejuni vaccine in chickens

目的拟研制一种可降低空肠弯曲菌在鸡肠道内定植的全菌灭活疫苗。方法利用一种新的灭活剂H;O;与CuCl;混合物灭活空肠弯曲菌制备油佐剂灭活疫苗,免疫SPF鸡后测定灭活疫苗诱导产生的特异性抗体水平,通过口服攻毒评价疫苗免疫对空肠弯曲菌在鸡盲肠内定植的影响,同时测定盲肠细胞因子在转录水平的变化,以及对盲肠绒毛长度和隐窝深度的影响。结果制备的全菌灭活疫苗免疫SPF鸡后可诱导产生特异性血清IgG和胆汁IgA,但口服攻毒后不能抑制或降低空肠弯曲菌在盲肠内的定植水平,且对免疫鸡的盲肠绒毛长度和隐窝深度无明显影响。测定的鸡盲肠中多数细胞因子在空肠弯曲菌攻毒前与攻毒后1 d的转录水平差异不明显,而在攻毒后10 d明显上升;同日龄样品比较结果显示,部分细胞因子的表达量在佐剂对照组和全菌免疫组较空白对照组明显上调。结论本试验研制的全菌灭活疫苗虽可诱导产生高水平特异性抗体,但不能降低空肠弯曲菌在鸡盲肠内的定植水平,提示空肠弯曲菌在鸡盲肠内的定植机制需深入探究。

On-farm vaccination of poultry against Campylobacter jejuni is considered a potentially effective strategy to decrease human campylobacteriosis. However, no commercial vaccines are currently available to inhibit or reduce the colonization of C. jejuni in poultry. To develop an inactivated whole-cell vaccine for decreasing C. jejuni colonization in chicken intestines, we used a novel inactivated agent and an H;O;and CuCl;mixture to kill C. jejuni cells and prepare an oil adjuvant inactivated whole-cell vaccine. SPF chickens were subcutaneously immunized with the inactivated whole-cell vaccine. The effects of the vaccine on the immunized chickens were evaluated on the basis of the induced anti-Campylobacter specific antibody levels, the C. jejuni colonization levels in chicken ceca after oral challenge, the transcriptional levels of cecal cytokines, and the cecal villus length and crypt depth. The inactivated whole-cell vaccine induced significantly higher levels of specific serum IgG and bile IgA in the vaccinated chickens. However, no significant decrease in the colonization level of C. jejuni in chicken ceca was observed between the vaccinated and unvaccinated groups. C. jejuni colonization in the chickens did not significantly affect the cecal villus length and crypt depth. Most cecal cytokines showed no significant difference in transcriptional levels before challenge and 1 day post inoculation(DPI) but a significant increase at 10 DPI. Comparison of cecal samples of the same age indicated that the transcriptional levels of some cytokines in the adjuvant immunized group and the whole-cell immunized group were significantly higher than those in the control group. These results indicated that the inactivated whole-cell vaccine did not decrease the colonization level of C. jejuni in the chicken cecum despite inducing high levels of specific antibodies. The colonization mechanism of C. jejuni in chicken cecum requires further exploration.