Jiang Yanlong, Mo Hua, Willingham Crystal, Wang Shifeng, Park Jie-Yeun, Kong Wei, Roland Kenneth L, Curtiss Roy
A Center for Infectious Diseases and Vaccinology, The Biodesign Institute, Arizona State University, Tempe, AZ 85287.
B School of Life Sciences, Arizona State University, Tempe, AZ 85287.
Avian Dis. 2015 Dec;59(4):475-85. doi: 10.1637/11094-041715-Reg.
Necrotic enteritis (NE), caused by Gram-positive Clostridium perfringens type A strains, has gained more attention in the broiler industry due to governmental restrictions affecting the use of growth-promoting antibiotics in feed. To date, there is only one commercial NE vaccine available, based on the C. perfringens alpha toxin. However, recent work has suggested that the NetB toxin, not alpha toxin, is the most critical virulence factor for causing NE. These findings notwithstanding, it is clear from prior research that immune responses against both toxins can provide some protection against NE. In this study, we delivered a carboxyl-terminal fragment of alpha toxin and a GST-NetB fusion protein using a novel attenuated Salmonella vaccine strain designed to lyse after 6-10 rounds of replication in the chicken host. We immunized birds with vaccine strains producing each protein individually, a mixture of the two strains, or with a single vaccine strain that produced both proteins. Immunization with strains producing either of the single proteins was not protective, but immunization with a mixture of the two or with a single strain producing both proteins resulted in protective immunity. The vaccine strain synthesizing both PlcC and GST-NetB was able to elicit strong production of intestinal IgA, IgY, and IgM antibodies and significantly protect broilers against C. perfringens challenge against both mild and severe challenges. Although not part of our experimental plan, the broiler chicks we obtained for these studies were apparently contaminated during transit from the hatchery with group D Salmonella. Despite this drawback, the vaccines worked well, indicating applicability to real-world conditions.
坏死性肠炎（NE）由革兰氏阳性A型产气荚膜梭菌引起，由于政府对饲料中促生长抗生素使用的限制，在肉鸡行业中受到了更多关注。迄今为止，基于产气荚膜梭菌α毒素，仅有一种商业化的NE疫苗。然而，最近的研究表明，NetB毒素而非α毒素是导致NE的最关键毒力因子。尽管有这些发现，但从先前的研究中可以清楚地看出，针对这两种毒素的免疫反应都能为NE提供一定的保护。在本研究中，我们使用一种新型减毒沙门氏菌疫苗株递送α毒素的羧基末端片段和GST-NetB融合蛋白，该疫苗株设计为在鸡宿主中经过6-10轮复制后裂解。我们用分别产生每种蛋白的疫苗株、两种菌株的混合物或产生两种蛋白的单一疫苗株对鸡进行免疫。用产生单一蛋白的菌株进行免疫没有保护作用，但用两种菌株的混合物或产生两种蛋白的单一菌株进行免疫则产生了保护性免疫。合成PlcC和GST-NetB的疫苗株能够引发肠道IgA、IgY和IgM抗体的大量产生，并显著保护肉鸡免受产气荚膜梭菌的轻度和重度攻击。尽管这不是我们实验计划的一部分，但我们用于这些研究的肉鸡雏鸡在从孵化场运输过程中显然被D组沙门氏菌污染了。尽管存在这个缺点，但疫苗效果良好，表明其适用于实际情况。
