Finlay B B, Starnbach M N, Francis C L, Stocker B A, Chatfield S, Dougan G, Falkow S
Department of Medical Microbiology, Stanford University School of Medicine, California 94305.
Mol Microbiol. 1988 Nov;2(6):757-66. doi: 10.1111/j.1365-2958.1988.tb00087.x.
Surface protein mutants of the invasive Salmonella species, S. choleraesuis, were generated using the transposon TnphoA. 626 alkaline phosphatase (PhoA+) fusion mutants were identified and screened for their ability to pass through (transcytose) polarized epithelial monolayers of Madin Darby canine kidney (MDCK) cells grown on membrane filters. Forty two mutants were unable to pass through this barrier. All of these transcytosis mutants were unable to adhere to or invade MDCK monolayers, yet these mutations were not in the genes encoding type 1 pili or mannose-resistant haemagglutination (MRHA). These transcytosis mutants could be grouped into six classes. Class 1 mutants had altered lipopolysaccharide (LPS) O side-chain structures while Class 2 mutants had defects in their LPS core. Mutants belonging to Classes 5 and 6 did not decrease the transepithelial electrical resistance of polarized MDCK cell monolayers, in contrast to the parental strain and the other mutants (Classes 1, 2, 3 and 4). Mutants belonging to Class 1 were less virulent in mice, while Class 2 (defective core) and Classes 4 and 5 (normal LPS) mutant strains were avirulent in mice. Mutants from Classes 3 and 6 were as virulent in mice as S. choleraesuis. These results suggest that the ability to pass through epithelial barriers may be an important virulence characteristic of Salmonella. These data indicate that bacterial adherence, internalization and monolayer transcytosis are closely linked events. It was also demonstrated that a mutant with decreased rates of intracellular replication still passed through the monolayer at rates similar to wild-type S. choleraesuis.
利用转座子TnphoA构建了侵袭性沙门氏菌猪霍乱沙门氏菌的表面蛋白突变体。鉴定出626个碱性磷酸酶（PhoA+）融合突变体，并筛选它们穿过（转胞吞）生长在膜滤器上的Madin Darby犬肾（MDCK）细胞极化上皮单层的能力。42个突变体无法穿过这一屏障。所有这些转胞吞突变体均无法黏附或侵入MDCK单层细胞，然而这些突变并非存在于编码1型菌毛或甘露糖抗性血凝素（MRHA）的基因中。这些转胞吞突变体可分为六类。1类突变体的脂多糖（LPS）O侧链结构发生改变，而2类突变体的LPS核心存在缺陷。与亲本菌株和其他突变体（1、2、3和4类）相比，5类和6类突变体不会降低极化MDCK细胞单层的跨上皮电阻。1类突变体在小鼠中的毒力较低，而2类（核心缺陷）以及4类和5类（LPS正常）突变株在小鼠中无毒力。3类和6类突变体在小鼠中的毒力与猪霍乱沙门氏菌相同。这些结果表明，穿过上皮屏障的能力可能是沙门氏菌的一个重要毒力特征。这些数据表明细菌黏附、内化和单层转胞吞是密切相关的事件。还证明了细胞内复制速率降低的突变体仍能以与野生型猪霍乱沙门氏菌相似的速率穿过单层细胞。
