Novel live vaccine strains of Mannheimia haemolytica serotypes (St)1 and St6, expressing and secreting inactive yet immunogenic leukotoxin (leukotoxoid) fused to antigenic domains of Mycoplasma bovis Elongation Factor Tu (EFTu) and Heat shock protein (Hsp) 70 were constructed and tested for efficacy in cattle. Control calves were administered an intranasal mixture of M. haemolytica St1 and St6 mutants (ΔlktCAV4) expressing and secreting leukotoxoid while vaccinated calves were administered an intranasal mixture of like M. haemolytica St1 and St6 leukotoxoid mutants coupled to M. bovis antigens (EFTu-Hsp70-ΔlktCAV4). Both M. haemolytica strains were recovered from palatine tonsils up to 34 days post intranasal exposure. On day 35 all calves were exposed to bovine herpes virus-1, four days later lung challenged with virulent M. bovis, then euthanized up to 20 days post-challenge. Results showed all cattle produced systemic antibody responses against M. haemolytica. The vaccinates also produced systemic antibody responses to M. bovis antigen, and concurrent reductions in temperatures, middle ear infections, joint infection and lung lesions versus the control group. Notably, dramatically decreased lung loads of M. bovis were detected in the vaccinated cattle. These observations indicate that the attenuated M. haemolytica vaccine strains expressing Mycoplasma antigens can control M. bovis infection and disease symptoms in a controlled setting.

构建并测试了曼海姆氏菌血清型 (St)1 和 St6 的新型活疫苗株，表达和分泌与牛支原体延伸因子 Tu (EFTu) 和热休克蛋白 (Hsp) 70抗原结构域融合的无活性但免疫原性白细胞毒素（leukotoxoid）用于牛的功效。对对照小牛施用表达和分泌白细胞毒素的溶血性支原体 St1 和 St6 突变体 (ΔlktCAV4) 的鼻内混合物，而接种疫苗的小牛施用与牛分枝杆菌抗原偶联的溶血性支原体 St1 和 St6 类白细胞毒素突变体的鼻内混合物（EFTu-Hsp700） -ΔlktCAV4)。这两个M.溶血鼻内暴露后最多 34 天从腭扁桃体中回收菌株。在第 35 天，所有小牛都暴露于牛疱疹病毒 1，四天后，肺用毒性牛支原体攻击，然后在攻击后 20 天实施安乐死。结果显示所有牛都产生了针对溶血性支原体的全身抗体反应。与对照组相比，疫苗接种者还产生了对牛分枝杆菌抗原的全身抗体反应，并同时降低了温度、中耳感染、关节感染和肺部病变。值得注意的是，在接种疫苗的牛中检测到牛分枝杆菌肺负荷显着降低。这些观察结果表明，减毒的M. haemolytica表达支原体抗原的疫苗株可以在受控环境中控制牛支原体感染和疾病症状。