Palma M, Nozohoor S, Schennings T, Heimdahl A, Flock J I
Department of Microbiology, Immunology, Pathology and Infectious Diseases, Karolinska Institutet, Huddinge University Hospital, Sweden.
Infect Immun. 1996 Dec;64(12):5284-9. doi: 10.1128/iai.64.12.5284-5289.1996.
A mutant deficient for the 19-kDa extracellular fibrinogen-binding protein (Fib) from Staphylococcus aureus has been constructed. The gene was inactivated by allele replacement. A 2.0-kb fragment from transposon Tn4001 carrying the gene for gentamicin resistance was inserted into the gene encoding Fib (fib). The genotype was verified by PCR analysis, and the loss of Fib was demonstrated by Western blotting (immunoblotting). The mutation has not altered the ability of the strain to bind to fibrinogen or fibronectin compared with that of the isogenic parental strain, FDA486. The mutant, designated K4.3, was compared with strain FDA486 in a wound infection model in rats. Sixty-eight percent of the rats challenged with parental strain FDA486 developed severe clinical signs of wound infection, whereas only 29% of the animals challenged with isogenic mutant K4.3 showed severe symptoms (P < 0.01). The weight loss of animals infected with the wild type was also significantly different from that of animals infected with the mutant strain. The result demonstrates that the extracellular 19-kDa fibrinogen-binding protein from S. aureus contributes to the virulence in wound infection and delays the healing process.
已构建出一株缺乏金黄色葡萄球菌19 kDa细胞外纤维蛋白原结合蛋白（Fib）的突变体。该基因通过等位基因替换被灭活。将携带庆大霉素抗性基因的转座子Tn4001的一个2.0 kb片段插入编码Fib（fib）的基因中。通过PCR分析验证基因型，并通过蛋白质印迹法（免疫印迹法）证实Fib缺失。与同基因亲本菌株FDA486相比，该突变未改变菌株与纤维蛋白原或纤连蛋白结合的能力。在大鼠伤口感染模型中，将命名为K4.3的突变体与菌株FDA486进行比较。用亲本菌株FDA486攻击的大鼠中有68%出现伤口感染的严重临床症状，而用同基因突变体K4.3攻击的动物中只有29%出现严重症状（P<0.01）。感染野生型的动物体重减轻也与感染突变菌株的动物显著不同。结果表明，金黄色葡萄球菌的细胞外19 kDa纤维蛋白原结合蛋白在伤口感染中有助于毒力，并延迟愈合过程。
