Necrotic enteritis (NE) causes significant economic losses and food shortages world-wide. There are currently no licensed commercial vaccines against NE in broilers. Chitosan nanoparticles were formulated with extracellular proteins of C. perfringens surface-tagged with Salmonella flagellar proteins. One-day-old male broiler chicks were completely randomized to 3 treatments: Non-vaccinated non-challenged as negative control, Vaccinated-challenged, and non-vaccinated challenge as positive control. On day of hatch, d7, and d14 post-hatch, vaccinated-challenged birds were orally gavage with 50µg vaccine in 0.5ml PBS while positive control birds were gavage with 0.5ml PBS only. Birds in the vaccinated-challenged and positive control groups were orally infected on d14 post-hatch, with 5,000 oocysts/bird of E. maxima , followed by log 8 CFU of a virulent strain of C. perfringens on d19, d20, and d21 post-hatch. From d14 to 21 and d14 to 28 post-hatches, mortality in the vaccinated-challenged group was higher than that in the positive control group, approaching statistical significance (p=0.07). On d21 post-hatch, the mean lesion score of 3 birds/cage in the vaccinated-challenged group was higher than the positive control group, approaching statistical significance (p = 0.05). From d 14 to 28 post-hatch, the feed intake was higher and feed conversion ratio lower in the vaccinated-challenged group compared to the positive control group (p<0.05). On d21 post-hatch, antigen specific recall proliferation in the vaccinated-challenged group was higher than that in the negative and positive control groups (p<0.05). On d21 post-hatch, cecal tonsils CD8 + T lymphocytes expression in the vaccinated-challenged group was similar to the negative control group (p>0.05) but higher than that in the positive control group (p<0.05). Finally, vaccination resulted in an increase in ileal mRNA levels of zonula occluding on d21 post-hatch. In conclusion, there were numerical but not statistically significant decrease in NE lesions and mortality in vaccinated and challenged broilers. Further studies are needed to improve the efficacy of the vaccine and understand the mechanism underlying protection in vaccinated birds.

中文翻译：

---

壳聚糖纳米颗粒疫苗装有产气荚膜梭菌和沙门氏菌的粗胞外蛋白，可部分预防肉鸡坏死性肠炎。

坏死性肠炎（NE）在全球范围内造成重大的经济损失和食物短缺。目前在肉鸡中没有针对NE的许可商业疫苗。壳聚糖纳米颗粒由产气荚膜梭菌胞外蛋白表面标记沙门氏菌鞭毛蛋白配制而成。将一天大的雄性肉鸡雏鸡完全随机分为3种处理方法：未接种非挑战性疫苗作为阴性对照，接种未挑战性疫苗和未接种挑战作为阳性对照。孵化当天，孵化后第7天和第14天，将接种过挑战的禽类用0.5ml PBS中的50μg疫苗口服灌胃，而阳性对照家禽只用0.5ml PBS进行灌胃。接种疫苗的挑战组和阳性对照组的鸟在孵化后第14天经口感染，每只大肠埃希氏菌有5,000个卵囊，然后在孵化后d19，d20和d21上对产气荚膜梭状芽孢杆菌的毒株进行log 8 CFU。孵化后第14至21天和孵化后第14至28天，接种疫苗的组的死亡率高于阳性对照组，接近统计学意义（p = 0.07）。孵化后第21天，接种疫苗的攻击组中3只鸟/笼的平均病变得分高于阳性对照组，接近统计学意义（p = 0.05）。孵化后第14天至第28天，与阳性对照组相比，接种挑战的组的采食量较高，饲料转化率较低（p <0.05）。孵化后第21天，接种疫苗的组的抗原特异性召回增殖高于阴性和阳性对照组（p <0.05）。在d21孵化后，接种挑战组的盲肠扁桃体CD8 + T淋巴细胞表达与阴性对照组相似（p> 0.05），但高于阳性对照组（p <0.05）。最后，接种疫苗导致孵化后d21闭合的回肠小肠回肠mRNA水平增加。总之，接种和感染的肉鸡的NE损伤和死亡率均下降，但无统计学意义。需要进行进一步的研究以提高疫苗的效力并了解疫苗接种禽类的潜在保护机制。总之，接种和感染的肉鸡的NE损伤和死亡率均下降，但无统计学意义。需要进一步的研究来提高疫苗的效力，并了解疫苗接种禽类的潜在保护机制。总之，接种和感染的肉鸡的NE损伤和死亡率均下降，但无统计学意义。需要进行进一步的研究以提高疫苗的效力并了解疫苗接种禽类的潜在保护机制。