Mammalian cell entry (mce) genes are the components of the mce operon and play a vital role in the entry of Mycobacteria into the mammalian cell and their survival within phagocytes and epithelial cells. Mce operons are present in the DNA of Mycobacteria and translate proteins associated with the invasion and long-term existence of these pathogens in macrophages. The exact mechanism of action of mce genes and their functions are not clear yet. However, with the loss of these genes Mycobacteria lose their pathogenicity. Mycobacterium avium subspecies paratuberculosis (MAP), the etiological agent of Johne’s disease, is the cause of chronic enteritis of animals and significantly affects economic impact on the livestock industry. Since MAP is not inactivated during pasteurization, human population is continuously at the risk of getting exposed to MAP infection through consumption of dairy products. There is need for new candidate genes and/or proteins for developing improved diagnostic assays for the diagnosis of MAP infection and for the control of disease. Increasing evidences showed that expression of mce genes is important for the virulence of MAP. Whole-genome DNA microarray representing MAP revealed that there are 14 large sequence polymorphisms with LSPP12 being the most widely conserved MAP-specific region that included a cluster of six homologs of mce-family involved in lipid metabolism. On the other hand, LSP11 comprising part of mce2 operon was absent in MAP isolates. This review summarizes the advancement of research on mce genes of Mycobacteria with special reference to the MAP infection.

哺乳动物细胞进入（mce）基因是mce操纵子的组成部分，在分枝杆菌进入哺乳动物细胞及其在吞噬细胞和上皮细胞中的存活中起着至关重要的作用。Mce操纵子存在于分枝杆菌的DNA中，并翻译与这些病原体在巨噬细胞中的侵袭和长期存在有关的蛋白质。mce基因的确切作用机理及其功能尚不清楚。然而，随着这些基因的丢失，分枝杆菌失去了其致病性。鸟分枝杆菌亚种副结核病（MAP）是Johne病的病原体，是动物慢性肠炎的病因，并极大地影响了对畜牧业的经济影响。由于MAP在巴氏灭菌过程中不会失活，因此人群持续面临通过食用乳制品而遭受MAP感染的风险。需要新的候选基因和/或蛋白质来开发用于诊断MAP感染和控制疾病的改进的诊断测定。越来越多的证据表明，mce基因的表达对于MAP的毒力很重要。表示MAP全基因组DNA微阵列显示，有14个LSPP12是最广泛保守的MAP大序列多态性-特定区域，该区域包括参与脂质代谢的mce家族的六个同源物簇。另一方面，在MAP分离物中不存在包含部分mce 2操纵子的LSP11 。本文综述了分枝杆菌mce基因的研究进展，特别是针对MAP感染的研究。