Mannheimia haemolyticais the major cause of severe pneumonia in bovine respiratory disease (BRD). EarlyM. haemolyticabacterins were either ineffective or even enhanced disease in vaccinated cattle, which led to studies of the bacterium's virulence factors and potential immunogens to determine ways to improve vaccines. Studies have focused on the capsule, lipopolysaccharide, various adhesins, extracellular enzymes, outer membrane proteins, and leukotoxin (LKT) resulting in a strong database for understanding immune responses to the bacterium and production of more efficacious vaccines. The importance of immunity to LKT and to surface antigens in stimulating immunity led to studies of individual native or recombinant antigens, bacterial extracts, live-attenuated or mutant organisms, culture supernatants, combined bacterin-toxoids, outer membrane vesicles, and bacterial ghosts. Efficacy of several of these potential vaccines can be shown following experimentalM. haemolyticachallenge; however, efficacy in field trials is harder to determine due to the complexity of factors and etiologic agents involved in naturally occurring BRD. Studies of potential vaccines have led current commercial vaccines, which are composed primarily of culture supernatant, bacterin-toxoid, or live mutant bacteria. Several of those can be augmented experimentally by addition of recombinant LKT or outer membrane proteins.

中文翻译：

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Mannheimia 溶血性牛呼吸道疾病：免疫原、潜在免疫原和疫苗

溶血曼海姆菌是牛呼吸道疾病（BRD）重症肺炎的主要原因。早期的溶血分枝杆菌在接种疫苗的牛中，菌苗要么无效，要么甚至加重疾病，这导致对细菌的毒力因子和潜在免疫原进行研究，以确定改进疫苗的方法。研究集中在胶囊、脂多糖、各种粘附素、细胞外酶、外膜蛋白和白细胞毒素 (LKT) 上，从而形成了一个强大的数据库，用于了解对细菌的免疫反应和生产更有效的疫苗。对 LKT 和表面抗原的免疫在刺激免疫方面的重要性导致了对单个天然或重组抗原、细菌提取物、减毒活或突变生物体、培养上清液、组合的细菌-类毒素、外膜囊泡和细菌幽灵的研究。这些潜在疫苗中的几种的功效可以在实验后显示溶血分枝杆菌挑战; 然而，由于自然发生的 BRD 所涉及的因素和病原体的复杂性，实地试验的疗效更难确定。对潜在疫苗的研究导致了目前的商业疫苗，这些疫苗主要由培养上清液、细菌类毒素或活突变细菌组成。其中一些可以通过添加重组 LKT 或外膜蛋白进行实验性增强。