National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China; Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China.
National Animal Protozoa Laboratory, College of Veterinary Medicine, China Agricultural University, Beijing, China; Key Laboratory of Animal Epidemiology of the Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China.
Poult Sci. 2021 Mar;100(3):100888. doi: 10.1016/j.psj.2020.12.001. Epub 2020 Dec 10.
Coccidiosis, caused by parasites of the genus Eimeria, is one of the most widespread and economically detrimental diseases in the global poultry industry. Because the merozoite stage of Eimeria tenella is immunologically vulnerable, motile, and functionally important for the parasites, the proteins expressed in these stages are considered to be potentially immunoprotective antigens, especially the secreted antigens and surface antigens. Here, we detected a previously unidentified MIC2-associated protein (Et-M2AP) from E. tenella and determined its localization. An immunofluorescence assay revealed that Et-M2AP was distributed in the apical part of second generation merozoites and sporozoites. In addition, an expression profile analysis revealed that the transcriptional level of Et-M2AP is significantly higher in the merozoite stage. To assess the potential of Et-M2AP protein as a coccidiosis vaccine, we expressed recombinant Et-M2AP (rEt-M2AP) and compared the immune protective efficacy of rEt-M2AP with 3 surface antigens that are highly expressed by merozoites (rEt-SAG23, rEt-SAG16, and rEt-SAG2 proteins). The immune protective efficacy of these vaccine candidates was assessed based on survival rate, lesion score, BW gain, relative BW gain, and oocyst output. The results show that the survival rate was 90%, which are significantly higher than those in the challenge control group. The BW gain rate was 42% (P < 0.001) in rEt-M2AP-immunized chickens, which are significantly higher than those in the challenge control group and rEt-SAG23, rEt-SAG16, and rEt-SAG2 proteins-immunized chickens. In addition, chickens immunized with rEt-M2AP (88% oocyst output decrease rate, P < 0.001) had the least oocyst output, compared with those immunized with rEt-SAG16 (59.2% oocyst output decrease rate, P < 0.001), rEt-SAG23 (22% oocyst output decrease rate), and rEt-SAG2 (1.36% oocyst output decrease rate). These results demonstrate that rEt-M2AP provided effective protection against challenge with E. tenella, suggesting that rEt-M2AP is a promising candidate antigen gene for development as a coccidiosis vaccine.
球虫病是由艾美耳属寄生虫引起的，是全球家禽业中最广泛和经济上危害最大的疾病之一。由于柔嫩艾美耳球虫的裂殖子阶段在免疫上很脆弱、能运动，并且对寄生虫的功能很重要，因此这些阶段表达的蛋白质被认为是潜在的免疫保护性抗原，特别是分泌抗原和表面抗原。在这里，我们从柔嫩艾美耳球虫中检测到了一种以前未被识别的 MIC2 相关蛋白（Et-M2AP），并确定了它的定位。免疫荧光分析显示，Et-M2AP 分布在第二代裂殖子和孢子的顶端部分。此外，表达谱分析显示，Et-M2AP 的转录水平在裂殖子阶段显著较高。为了评估 Et-M2AP 蛋白作为球虫病疫苗的潜力，我们表达了重组 Et-M2AP（rEt-M2AP），并比较了 rEt-M2AP 与高度表达于裂殖子的 3 种表面抗原（rEt-SAG23、rEt-SAG16 和 rEt-SAG2 蛋白）的免疫保护效力。这些候选疫苗的免疫保护效力是基于存活率、病变评分、体重增加、相对体重增加和卵囊产量来评估的。结果表明，存活率为 90%，明显高于攻毒对照组。rEt-M2AP 免疫组鸡的体重增长率为 42%（P<0.001），明显高于攻毒对照组和 rEt-SAG23、rEt-SAG16 和 rEt-SAG2 蛋白免疫组鸡。此外，rEt-M2AP 免疫组鸡的卵囊产量下降率为 88%（P<0.001），与 rEt-SAG16 免疫组鸡的 59.2%（P<0.001）、rEt-SAG23 免疫组鸡的 22%和 rEt-SAG2 免疫组鸡的 1.36%相比，卵囊产量最少。这些结果表明，rEt-M2AP 对柔嫩艾美耳球虫的攻毒提供了有效的保护，表明 rEt-M2AP 是一种很有前途的球虫病疫苗候选抗原基因。
