VI型分泌系统2核心组分VgrG对禽致病性大肠杆菌致病性的影响

【目的】构建禽致病性大肠杆菌(Avian pathogenic Escherichia coli,APEC)VI型分泌系统2(Type VI secretion system 2,T6SS2)结构基因vgrG缺失株,研究其对APEC生物学特性及致病性的影响。【方法】通过Red同源重组方法构建DE719菌株vgrG基因缺失株,并利用低拷贝质粒pSTV28构建互补株。比较分析野生株、缺失株与互补株的生长特性、运动性、生物被膜形成能力、黏附侵袭能力、动物致病力等差异。【结果】vgr G基因缺失不影响DE719的生长速度、运动能力及生物被膜形成能力。致病性试验表明缺失vgrG导致体内定殖能力及致病力显著下降,然而对DF-1细胞的黏附能力增强。【结论】T6SS2核心组分VgrG在APEC感染过程中发挥重要作用,为了解APEC的致病作用提供参考。

Effects of type VI secretion system 2 core component VgrG on the pathogenicity of avian Escherichia coli

Objective] To determine the role of type VI secretion system 2 (T6SS2) core component VgrG in avian pathogenic Escherichia coli (APEC), we detected the biological characteristics and pathogenicity of APEC vgrG gene mutant strain. Methods] We constructed the vgrG gene mutant strain and complementary strain of APEC DE719 by the Red recombination system and plasmid pSTV28. Then we analyzed the growth curve, motility, biofilm formation, adhesion and invasion capacity to DF-1 cells and virulence to duck of wild-type strain, mutant strain and complementary strain. Results] The inactivation of vgrG gene did not affect the growth and motility, nor the biofilm formation of APEC. The vgrG gene mutant showed significantly decreased survival capacity and attenuated virulence in ducks. However, the adhesion capacity to DF-1 cells increased. Conclusion] T6SS2 core component VgrG was involved in the process of APEC infection, which would help us to comprehensive understand the pathogenicity of APEC.