Kulkarni R R, Parreira V R, Sharif S, Prescott J F
Department of Pathobiology, University of Guelph, Guelph, Ontario N1G 2W1, Canada.
Clin Vaccine Immunol. 2007 Sep;14(9):1070-7. doi: 10.1128/CVI.00162-07. Epub 2007 Jul 18.
Necrotic enteritis (NE) in broiler chickens is caused by Clostridium perfringens. Currently, no vaccine against NE is available and immunity to NE is not well characterized. Our previous studies showed that immunity to NE followed oral infection by virulent rather than avirulent C. perfringens strains and identified immunogenic secreted proteins apparently uniquely produced by virulent C. perfringens isolates. These proteins were alpha-toxin, glyceraldehyde-3-phosphate dehydrogenase, pyruvate:ferredoxin oxidoreductase (PFOR), fructose 1,6-biphosphate aldolase, and a hypothetical protein (HP). The current study investigated the role of each of these proteins in conferring protection to broiler chickens against oral infection challenges of different severities with virulent C. perfringens. The genes encoding these proteins were cloned and purified as histidine-tagged recombinant proteins from Escherichia coli and were used to immunize broiler chickens intramuscularly. Serum and intestinal antibody responses were assessed by enzyme-linked immunosorbent assay. All proteins significantly protected broiler chickens against a relatively mild challenge. In addition, immunization with alpha-toxin, HP, and PFOR also offered significant protection against a more severe challenge. When the birds were primed with alpha-toxoid and boosted with active toxin, birds immunized with alpha-toxin were provided with the greatest protection against a severe challenge. The serum and intestinal washings from protected birds had high antigen-specific antibody titers. Thus, we conclude that there are certain secreted proteins, in addition to alpha-toxin, that are involved in immunity to NE in broiler chickens.
肉鸡坏死性肠炎（NE）由产气荚膜梭菌引起。目前，尚无针对NE的疫苗，且对NE的免疫特性尚不明确。我们之前的研究表明，对NE的免疫是在感染强毒株而非无毒株产气荚膜梭菌后产生的，并鉴定出了强毒株产气荚膜梭菌分离株明显独特产生的免疫原性分泌蛋白。这些蛋白包括α毒素、甘油醛-3-磷酸脱氢酶、丙酮酸：铁氧化还原蛋白氧化还原酶（PFOR）、果糖1,6-二磷酸醛缩酶和一种假定蛋白（HP）。本研究调查了这些蛋白各自在保护肉鸡抵抗强毒株产气荚膜梭菌不同严重程度口服感染挑战中的作用。编码这些蛋白的基因被克隆并从大肠杆菌中纯化出来作为带组氨酸标签的重组蛋白，用于对肉鸡进行肌肉注射免疫。通过酶联免疫吸附测定评估血清和肠道抗体反应。所有蛋白均能显著保护肉鸡抵抗相对温和的挑战。此外，用α毒素、HP和PFOR免疫也能提供显著保护抵抗更严重的挑战。当用α类毒素对鸡进行初免并用活性毒素进行加强免疫时，用α毒素免疫的鸡对严重挑战具有最大的保护作用。受保护鸡的血清和肠道冲洗液具有高抗原特异性抗体滴度。因此，我们得出结论，除α毒素外，还有某些分泌蛋白参与了肉鸡对NE的免疫。
