Institute of Veterinary Bacteriology, Vetsuisse Faculty, University of Bern, Bern, Switzerland.
Graduate School for Cellular and Biomedical Sciences, University of Bern, Bern, Switzerland.
Vet Res. 2019 Jul 19;50(1):55. doi: 10.1186/s13567-019-0674-7.
Mycoplasma hyopneumoniae and Mycoplasma hyorhinis are two phylogenetically related species colonizing the respiratory tract of pigs but differing in pathogenicity, the basis of which is not well resolved. We hypothesize that genes belonging to the species-specific portion of the genome and being non-essential during ideal laboratory growth conditions encode possible virulent determinants and are the driver of interspecies differences. To investigate this, transposon mutant libraries were generated for both species and a transposon sequencing (Tn-seq) method for mycoplasmas was established to identify non-essential genes. Tn-seq datasets combined with bidirectional Blastp analysis revealed that 101 out of a total 678 coding sequences (CDS) are species-specific and non-essential CDS of M. hyopneumoniae strain F7.2C, while 96 out of a total 751 CDS are species-specific and non-essential CDS in the M. hyorhinis strain JF5820. Among these species-specific and non-essential CDS were genes involved in metabolic pathways. In particular, the myo-inositol and the sialic acid pathways were found to be non-essential and therefore could be considered important to the specific pathogenicity of M. hyopneumoniae and M. hyorhinis, respectively. Such pathways could enable the use of an alternative energy source providing an advantage in their specific niche and might be interesting targets to knock out in order to generate attenuated live vaccines.
猪肺炎支原体和猪鼻支原体是两种在猪呼吸道定植的具有系统发育相关性的物种，但在致病性方面存在差异，而其差异的基础尚不清楚。我们假设，属于基因组物种特异性部分且在理想的实验室生长条件下非必需的基因可能编码潜在的毒力决定因素，是种间差异的驱动因素。为此，我们针对这两个物种生成了转座子突变体文库，并建立了一种用于支原体的转座子测序（Tn-seq）方法，以鉴定非必需基因。Tn-seq 数据集与双向 Blastp 分析相结合，揭示了总共 678 个编码序列（CDS）中有 101 个是 M. hyopneumoniae 菌株 F7.2C 的物种特异性和非必需 CDS，而在总共 751 个 CDS 中有 96 个是 M. hyorhinis 菌株 JF5820 的物种特异性和非必需 CDS。在这些物种特异性和非必需的 CDS 中，有一些基因参与了代谢途径。特别是，肌醇和唾液酸途径被发现是非必需的，因此可以分别被认为是 M. hyopneumoniae 和 M. hyorhinis 特定致病性的重要因素。这些途径可以使它们能够利用替代能源，从而在其特定的小生境中获得优势，并且可能是敲除以生成减毒活疫苗的有趣靶点。
