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目的构建猪链球菌2型(Streptococcus suisserotype 2,S.suis2)中国强致病株05ZYH33荚膜缺陷株。方法利用同源重组基因敲除方法获得S.suis2强毒株05ZYH33荚膜合成基因cps2B敲除突变株,通过小鼠攻毒实验证实荚膜缺陷株对细菌毒力的影响。结果PCR和Southern杂交结果均显示cps2B基因完全被壮观霉素抗性基因替代,表明基因敲除突变体构建成功。电镜结果证实突变体荚膜合成能力缺失,小鼠致病性实验结果显示突变体毒力基本丧失。结论成功构建05ZYH33荚膜缺陷株,提示菌体荚膜多糖成分对于猪链球菌2型侵袭和致病具有显著作用。
Objective To construct a Streptococcus suisserotype 2 (S.suis2) Chinese virulent strain 05ZYH33 capsular defect. Methods The homologous recombination gene knockout method was used to obtain the cps2B knockout mutant of the virulent strain 05suYt2 capsid of S.suis2. The effects of capsular defective strains on the virulence of bacteria were confirmed by the challenge experiments in mice. Results The PCR and Southern hybridization results showed that the cps2B gene was completely replaced by the spectinomycin resistance gene, indicating that the knockout mutant was successfully constructed. Electron microscopy confirmed that the mutant capsular synthesis absent, the pathogenicity of mice showed that the mutant virulence of basic loss. Conclusion 05ZYH33 capsular defect was successfully constructed, suggesting that the components of the capsular polysaccharide of the strain play a significant role in the invasion and pathogenesis of Streptococcus suis type 2.