表达鸡传染性法氏囊病毒VP2蛋白的干酪乳杆菌免疫保护效力

Immunogenicity of recombinant Lactobacillus casei expressing VP2 protein of infectious bursal disease virus in chickens

摘要:

利用干酪乳杆菌作为传染性法氏囊病毒 (IBDV)VP2抗原传递系统，探讨口服雏鸡的免疫次数、免疫剂量、免疫途径和攻毒保护效果。用pLA-VP2重组干酪乳杆菌对5日龄雏鸡进行二次和三次免疫，并设108、109、1010 CFU/mL的重组干酪乳杆菌组，间接ELISA检测血清IgG和小肠洗液sIgA，末免后7 d攻毒，计算保护效果。根据确定的2次免疫和109 CFU/mL免疫剂量免疫5日龄雏鸡，分别口服、滴鼻/点眼pLA-VP2/L. casei，口服、肌注商品活苗及口服pLA/L. casei和PBS为对照，监测IgG和sIgA抗体水平；末免后7 d检测脾淋巴细胞增殖情况并攻毒，7 d后剖检，观察法氏囊损伤程度并记录病变得分和保护率。结果表明各组的特异性sIgA、IgG抗体水平显著高于对照组 (P<0.01)；口服pLA-VP2/L. casei组的淋巴细胞刺激指数显著高于其他组 (P<0.01)，保护率高达83.3%，免疫保护效果优于滴鼻/点眼组。因此，构建的重组干酪乳杆菌的安全性优于商品活苗，可以作为IBDV候选疫苗。

Abstract:

In order to determine immunogenicity and protective effect in chickens, we used the IBDV (Infectious bursal disease virus)-Vp2/Lactobacillus casei as antigen transfer system. First, the immunized and control chickens were challenged by IBDV/DQ at lethal dose to determine the protective ratio. Second, chickens were orallyand intranasally vaccinated twice with 109 CFU/mL pLA-VP2/L. casei, pLA/L. casei and PBS as negativecontrol and commercial vaccine as positive control. The bursa injury and the lesion score wererecorded post challenge. The level of specific IgG and sIgA in pLA-VP2/L. casei and positive control groups was significantly higher than that in negativecontrol groups. The protection efficacy in pLA-VP2/L. casei oral group was higher than that inintranasal group. The SI. of pLA-VP2/L. casei oral group was significant higher than other groups. The lesion score indicated the pLA-VP2/L. casei was safer than commercial vaccine for bursa. Collectively, the pLA-VP2/L. casei could be a vaccine candidate for IBDV.