Abstract：
Mycoplasma bovis is an important emerging pathogen of cattle and bison, but our understanding of the genetic basis of its interactions with its host is limited. The aim of this study was to identify genes of M. bovis required for interaction and survival in association with host cells. One hundred transposon-induced mutants of the type strain PG45 were assessed for their capacity to survive and proliferate in Madin-Darby bovine kidney cell cultures. The growth of 19 mutants was completely abrogated, and 47 mutants had a prolonged doubling time compared to the parent strain. All these mutants had a similar growth pattern to the parent strain PG45 in the axenic media. Thirteen genes previously classified as dispensable for the axenic growth of M. bovis were found to be essential for the growth of M. bovis in association with host cells. In most of the mutants with a growth-deficient phenotype, the transposon was inserted into a gene involved in transportation or metabolism. This included genes coding for ABC transporters, proteins related to carbohydrate, nucleotide and protein metabolism, and membrane proteins essential for attachment. It is likely that these genes are essential not only in vitro but also for the survival of M. bovis in infected animals.
OBJECTIVE: Mycoplasma bovis causes chronic bronchopneumonia, mastitis, arthritis, keratoconjunctivitis, and reproductive tract disease in cattle around the globe and is an emerging pathogen in bison. Control of mycoplasma infections is difficult in the absence of appropriate antimicrobial treatment or effective vaccines. A comprehensive understanding of host-pathogen interactions and virulence factors is important to implement more effective control methods against M. bovis. Recent studies of other mycoplasmas with in vitro cell culture models have identified essential virulence genes of mycoplasmas. Our study has identified genes of M. bovis required for survival in association with host cells, which will pave the way to a better understanding of host-pathogen interactions and the role of specific genes in the pathogenesis of disease caused by M. bovis.
OBJECTIVE: Mycoplasma bovis causes chronic bronchopneumonia, mastitis, arthritis, keratoconjunctivitis, and reproductive tract disease in cattle around the globe and is an emerging pathogen in bison. Control of mycoplasma infections is difficult in the absence of appropriate antimicrobial treatment or effective vaccines. A comprehensive understanding of host-pathogen interactions and virulence factors is important to implement more effective control methods against M. bovis. Recent studies of other mycoplasmas with in vitro cell culture models have identified essential virulence genes of mycoplasmas. Our study has identified genes of M. bovis required for survival in association with host cells, which will pave the way to a better understanding of host-pathogen interactions and the role of specific genes in the pathogenesis of disease caused by M. bovis.
摘要：
牛支原体是牛和野牛的重要新兴病原体，但是我们对其与宿主相互作用的遗传基础的理解是有限的。这项研究的目的是鉴定牛分枝杆菌与宿主细胞相互作用和存活所需的基因。评估了一百个转座子诱导的PG45型菌株突变体在Madin-Darby牛肾细胞培养物中的存活和增殖能力。19个突变体的生长完全消失，与亲本菌株相比，47个突变体的倍增时间延长。所有这些突变体在无菌培养基中具有与亲本菌株PG45相似的生长模式。发现先前被分类为对牛分枝杆菌的轴性生长可有可无的13个基因对于与宿主细胞相关的牛分枝杆菌的生长是必需的。在大多数具有生长缺陷表型的突变体中，转座子被插入到与运输或代谢有关的基因中。这包括编码ABC转运蛋白的基因，与碳水化合物有关的蛋白质，核苷酸和蛋白质代谢，和附着所必需的膜蛋白。这些基因可能不仅在体外而且对于牛分枝杆菌在感染动物中的存活都是必需的。
目的：牛支原体引起慢性支气管肺炎，乳腺炎,关节炎,角膜结膜炎，和全球牛的生殖道疾病，是野牛的新兴病原体。在缺乏适当的抗微生物治疗或有效疫苗的情况下,难以控制支原体感染。全面了解宿主-病原体相互作用和毒力因子对于实施更有效的针对牛分枝杆菌的控制方法很重要。最近使用体外细胞培养模型对其他支原体进行的研究已经确定了支原体的必需毒力基因。我们的研究已经确定了与宿主细胞相关的牛分枝杆菌存活所需的基因，这将为更好地理解宿主与病原体的相互作用以及特定基因在牛分枝杆菌引起的疾病的发病机理中的作用铺平道路。
目的：牛支原体引起慢性支气管肺炎，乳腺炎,关节炎,角膜结膜炎，和全球牛的生殖道疾病，是野牛的新兴病原体。在缺乏适当的抗微生物治疗或有效疫苗的情况下,难以控制支原体感染。全面了解宿主-病原体相互作用和毒力因子对于实施更有效的针对牛分枝杆菌的控制方法很重要。最近使用体外细胞培养模型对其他支原体进行的研究已经确定了支原体的必需毒力基因。我们的研究已经确定了与宿主细胞相关的牛分枝杆菌存活所需的基因，这将为更好地理解宿主与病原体的相互作用以及特定基因在牛分枝杆菌引起的疾病的发病机理中的作用铺平道路。
