鸡败血支原体pMGA多基因家族及其免疫逃逸机制的研究进展

Developments on pMGA Multigene Family and Evasion Mechanism of Mycoplasma gallisepticum

p MGA多基因家族主要编码一类黏附素 /血凝素蛋白 ,存在于鸡败血支原体的细胞表面 ,其主要功能是促进支原体黏附到宿主细胞上。近年来的相关研究发现 ,编码 p MGA的基因数量从 3 2～ 70不等 ,主要在转录水平上通过 ( GAA) n基序的数量改变引发 p MGA基因的选择性转录 ,造成 p MGA蛋白的抗原发生变异 ,从而干扰宿主正常免疫功能的发挥 ,使支原体对宿主产生严重的免疫逃逸。其中 ,( GAA) n基序已被证实在 p MGA基因表达调控中起重要作用。这一三联体重复基序数目的多少直接影响到 p MGA基因的 ON/OFF转录。本文通过对鸡败血支原体 p MGA多基因家族分子生物学研究进展进行浅要综述 ,以提出p MGA基因可能的转录调控机制。这对研究鸡败血支原体的分子致病机理及其免疫逃逸机制大有裨益。

The pMGA multigene family encodes variant copies of the cell surface Adhesin/Haemagglutinin of Mycoplasma gallisepticum. The number of copies estimated to be present in the genome varied from 32 in strain F to 70 in strain R. Now that (GAA)n motif has been proved to be important in the regulation of pMGA genes expression, the number of the trinucleotide repeats could serve as a transcript switch. In the review, there were developments on molecular biology of pMGA multigene family of Mycoplasma gallisepticum (MG), focusing on the role of (GAA)n motif., which can help the studies on the pathogenetic mechanism and the evasion of MG from the immune systems.