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【目的】为了研究肺炎链球菌(Streptococcus pneumoniae,S.pn)的一种假想的溶菌酶样蛋白在细菌生物学性状及其致病中的作用。【方法】利用长臂同源PCR对该基因进行敲出,并同时构建带有拯救质粒的缺失菌株,观察D39野生菌、缺失菌与带有拯救质粒的缺失菌株在相关生物学性状及其致病力改变,从而鉴定这种假想溶菌酶样蛋白的功能。【结果】缺失菌与野生菌相比,细菌生长减缓,毒力下降,荚膜多糖合成明显减少。而将拯救质粒转入缺失菌株后,该溶菌酶样蛋白的mRNA表达水平较野生菌高,其毒力及荚膜合成较缺失菌显著增高,但未达到野生菌水平。【结论】这种溶菌酶样蛋白是肺炎链球菌的一种新毒力因子,可能通过参与调控肺炎链球菌增殖及荚膜多糖的表达而影响毒力。
【Objective】 To investigate the role of an imaginary lysozyme-like protein of Streptococcus pneumoniae (S.pn) in bacterial biological traits and its pathogenesis. 【Method】 The gene was knocked out by homologous PCR with long arm and at the same time, a deletion strain with the rescue plasmid was constructed. The effects of the deletion of the wild strain D39, the deletion strain and the deletion plasmid with the rescue plasmid on the related biological characters Changes in disease to identify the function of this imaginary lysozyme-like protein. 【Result】 Compared with wild-type bacteria, the growth of bacteria was slowed and the virulence decreased. The synthesis of capsular polysaccharide was significantly reduced. However, when the rescue plasmid was transformed into the deletion strain, the expression level of lysozyme-like protein was higher than that of wild-type strain. The virulence and capsular synthesis of the lysozyme-like protein were significantly increased compared with the absence of wild type strain. 【Conclusion】 This lysozyme-like protein is a new virulence factor of Streptococcus pneumoniae and may affect its virulence by participating in the regulation of the proliferation of Streptococcus pneumoniae and the expression of capsular polysaccharide.