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目的构建2型猪链球菌中国强毒株05ZYH33菌毛蛋白编码基因SSU0474缺失突变株,并对其生物学特性进行分析。方法利用同源重组原理构建SSU0474缺失突变株,PCR及RT-PCR对筛选的突变株进行验证,革兰染色和电镜比较突变株SSU0474与野毒株之间的差异,小鼠实验进一步比较突变株的毒力变化。结果引物特异性PCR证实SSU0474基因缺失突变株构建成功;革兰染色结果显示突变株和野毒株染色特性差异无统计学意义,SSU0474基因的缺失未明显影响细菌的生长速率;电镜结果表明突变株SSU0474细胞壁明显变薄,细菌菌毛样附属结构缺失;小鼠毒力实验结果提示突变株SSU0474的毒力明显下降。结论本研究成功获得菌毛蛋白编码基因SSU0474缺失突变株,并对该基因的生物学特性进行了初步探讨,为系统研究2型猪链球菌中国强毒株05ZYH33菌毛的生物学功能提供依据。
Objective To construct a mutant strain of Streptococcus suis serotype 2 Streptococcus suis serotype 05ZYH33 pusillus encoding gene SSU0474 deletion mutant and analyze its biological characteristics. Methods The SSU0474 deletion mutant was constructed by homologous recombination. The selected strains were verified by PCR and RT-PCR. The differences between mutant strain SSU0474 and wild-type strain were compared by Gram stain and electron microscope. Toxicity changes. Results The primer-specific PCR confirmed that SSU0474 gene deletion mutant was successfully constructed. The results of Gram stain showed no significant difference in the staining characteristics between the mutant strain and the wild-type strain. The deletion of SSU0474 gene did not affect the growth rate of the bacteria. The electron microscopy results showed that the mutant strain The cell wall of SSU0474 was obviously thinned, and the accessory structure of bacterial pilus was absent. The virulence of mice showed that the virulence of mutant strain SSU0474 was obviously decreased. Conclusion This study successfully obtained pus protein coding gene SSU0474 deletion mutant, and the biological characteristics of the gene were initially explored to provide a basis for systematic study of the biological function of Streptococcus suis serotype 2 05ZYH33 pili.