Inhibiting F. tularensis Adherence to Alveolar Type II Cells as a Vaccine Strateg

摘要 土拉方杆菌具有繁殖容易、寄主范围广、传播途径多、毒力强等特点，是一种潜在的生物武器。发病率和死亡率最高的是吸入图拉氏丝虫引起的肺炎性图拉热症。我们发现吸入图拉氏F菌与肺泡II型(ATII)上皮细胞和转座子有关 在吸入性感染模型中，侵入但不在ATII细胞内复制的插入突变体显著减弱。细胞结合分析结果表明，图拉氏原虫在体外表达一种预形成的粘附素，介导ATII细胞的附着和侵袭。介导AT-II细胞黏附和侵袭的细菌配体(S)将通过筛选图拉氏酵母基因组文库来鉴定 在大肠杆菌中表达。通过对整个图拉氏F菌的糖链阵列的探测，我们发现图拉氏杆菌与糖链阵列上的Mana1-6(Mana1-3)Mana1-6(Mana2Mana1-3)Man¿1-4GlcNAc¿1-4GlcNAc¿-Sp12特异结合，平均荧光强度单位为3766+94个单位，变异系数为2%，表明这种结合既有特异性又有意义。我们正在努力确定与这种复杂碳水化合物的结合在图拉氏丝虫毒力和致病机制中所起的作用。

Abstract The bacterial pathogen Francisella tularensis is a potential biological weapon by virtue of its ease of propagation, broad host range, myriad of transmission routes and extraordinary virulence. The highest morbidity and mortality is associated with pneumonic tularemia initiated by inhalation of F. tularensis. We found that inhaled F. tularensis associate within alveolar Type II (ATII) epithelial cells, and a transposon insertion mutant that invades, but does not replicate within, ATII cells was significantly attenuated in an inhalation model of infection. Results from cell association assays demonstrated that F. tularensis expressed a pre-formed adhesin that mediates attachment and invasion of ATII cells in vitro. The bacterial ligand(s) that mediate AT-II cell adherence and invasion will be identified by screening F. tularensis genomic libraries expressed in E. coli. Through probing of glycan arrays with whole F. tularensis bacteria we found that F. tularensis bound specifically to Mana1-6(Mana1-3)Mana1-6(Mana2Mana1-3)Man¿1-4GlcNAc¿1-4GlcNAc¿-Sp12 on the glycan ¿ array at an average of 3766 + 94 fluorescence intensity units with a 2% coefficient of variance suggesting that the binding was both specific and significant. We are working to determine the role that binding to this complex carbohydrate plays in F. tularensis virulence and pathogenesis.