Jonsson Ing-Marie, Pietrocola Giampiero, Speziale Pietro, Verdrengh Margareta, Tarkowski Andrzej
Department of Rheumatology and Inflammation Research, Goteborg University, Goteborg, Sweden.
J Infect Dis. 2005 Oct 15;192(8):1456-64. doi: 10.1086/491478. Epub 2005 Sep 12.
Streptococcus agalactiae (group B streptococcus) is an important human pathogen that causes neonatal pneumonia, sepsis, septic arthritis, and meningitis, as well as severe infections in immunocompromised adult patients. The streptococci produce several molecules important for virulence.
We used a murine model of sepsis and septic arthritis to assess the role of FbsA, a fibrinogen-binding adhesin of S. agalactiae as a virulence determinant. NMRI mice were inoculated intravenously with S. agalactiae strains isogenic for the expression of FbsA.
Inoculation with wild-type (wt) streptococci resulted in significantly higher mortality, more-pronounced weight decrease, and more-severe arthritis, compared with inoculation with the FbsA mutant isogenic strain. Neither active nor passive immunization with FbsA or FbsA-specific antibodies, respectively, resulted in any protection against subsequent infection with the S. agalactiae wt strain.
Our results clearly indicate that the expression of FbsA by Streptococcus agalactiae is a significant virulence determinant in septic arthritis and septicemia. However, because blocking of the fibrinogen binding properties did not protect the host against the action of FbsA-expressing streptococci, we believe that the FbsA molecule has some other presently unknown biological in vivo properties.
无乳链球菌（B族链球菌）是一种重要的人类病原体，可导致新生儿肺炎、败血症、化脓性关节炎和脑膜炎，以及免疫功能低下的成年患者发生严重感染。链球菌产生几种对毒力很重要的分子。
我们使用败血症和化脓性关节炎的小鼠模型来评估无乳链球菌的纤维蛋白原结合黏附素FbsA作为毒力决定因素的作用。将表达FbsA的等基因无乳链球菌菌株静脉注射到NMRI小鼠体内。
与接种FbsA突变等基因菌株相比，接种野生型（wt）链球菌导致死亡率显著更高、体重下降更明显、关节炎更严重。分别用FbsA或FbsA特异性抗体进行主动或被动免疫，均未对随后感染无乳链球菌wt菌株产生任何保护作用。
我们的结果清楚地表明，无乳链球菌表达FbsA是化脓性关节炎和败血症中的一个重要毒力决定因素。然而，由于阻断纤维蛋白原结合特性并不能保护宿主免受表达FbsA的链球菌的作用，我们认为FbsA分子具有一些目前未知的体内生物学特性。
