New vaccine formulations that include novel strains of Mycoplasma hyopneumoniae and innovative adjuvants designed to induce cellular immunity could improve vaccine efficacy against this pathogen. The aim of this experimental study was to assess the efficacy of three experimental bacterin formulations based on M. hyopneumoniae field strain F7.2C which were able to induce cellular immunity. The formulations included a cationic liposome formulation with the Mincle receptor ligand trehalose 6,6-dibehenate (Lipo_DDA:TDB), a squalene-in-water emulsion with Toll-like receptor (TLR) ligands targeting TLR1/2, TLR7/8 and TLR9 (SWE_TLR), and a poly(lactic-co-glycolic acid) micro-particle formulation with the same TLR ligands (PLGA_TLR). Four groups of 12 M. hyopneumoniae-free piglets were primo- (day (D) 0; 39 days of age) and booster vaccinated (D14) intramuscularly with either one of the three experimental bacterin formulations or PBS. The pigs were endotracheally inoculated with a highly and low virulent M. hyopneumoniae strain on D28 and D29, respectively, and euthanized on D56. The main efficacy parameters were: respiratory disease score (RDS; daily), macroscopic lung lesion score (D56) and log copies M. hyopneumoniae DNA determined with qPCR on bronchoalveolar lavage (BAL) fluid (D42, D56). All formulations were able to reduce clinical symptoms, lung lesions and the M. hyopneumoniae DNA load in the lung, with formulation SWE_TLR being the most effective (RDSD28-D56 -61.90%, macroscopic lung lesions -88.38%, M. hyopneumoniae DNA load in BAL fluid (D42) -67.28%). Further experiments raised under field conditions are needed to confirm these results and to assess the effect of the vaccines on performance parameters.

中文翻译：

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三种创新性细菌疫苗对猪肺炎支原体实验性感染的功效。

包括猪肺炎支原体的新菌株和旨在诱导细胞免疫的创新佐剂在内的新疫苗制剂可以提高针对这种病原体的疫苗效力。这项实验研究的目的是评估三种基于猪肺炎支原体田间菌株F7.2C的实验性细菌制剂的功效，该制剂能够诱导细胞免疫。该制剂包括阳离子脂质体制剂，该脂质体制剂具有Mincle受体配体海藻糖6,6-二苯二酸酯（Lipo_DDA：TDB），具有靶向TLR1 / 2，TLR7 / 8和TLR9的Toll样受体（TLR）配体的角鲨烯水乳液。 （SWE_TLR），以及具有相同TLR配体的聚乳酸-乙醇酸共聚物微粒（PLGA_TLR）。四组12只无猪肺炎支原体的仔猪为初生（第（D）天； 0；39天龄），并用三种实验性细菌制剂之一或PBS肌肉注射（D14）加强疫苗。在猪的气管内分别在D28和D29上接种高毒力和低毒力的猪肺炎支原体菌株，并在D56处安乐死。主要功效参数为：呼吸道疾病评分（RDS；每日），宏观肺损伤评分（D56）和通过qPCR在支气管肺泡灌洗液（BAL）上测定的猪肺炎支原体DNA的对数拷贝（D42，D56）。所有制剂均能够减轻临床症状，肺部病变和肺中肺炎支原体DNA负荷，其中SWE_TLR制剂最为有效（RDSD28-D56 -61.90％，肉眼可见的肺部病变-88.38％，肺炎支原体DNA负荷BAL流体（D42）-67.28％）。