the cost of virulence retarded growth of salmonella typhimurium cells expressing type iii secretion system 1鼠伤寒沙门氏菌细胞的毒性生长阻滞成本表达iii型分泌系统1.pdf

The Cost of Virulence: Retarded Growth of Salmonella Typhimurium Cells Expressing Type III Secretion System 1 1 2 3 4 3 Alexander Sturm , Matthias Heinemann , Markus Arnoldini , Arndt Benecke , Martin Ackermann , 1 1 1 Matthias Benz , Jasmine Dormann , Wolf-Dietrich Hardt * ¨ 1 Institute of Microbiology, ETH Zurich, Zurich, Switzerland, 2 Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The ¨ Netherlands, 3 Institute of Biogeochemistry and Pollutant Dynamics, ETH Zurich and Department of Environmental Microbiology, Eawag, Switzerland, 4 Institut des ´ ´ Hautes Etudes Scientifiques Institut de Recherche Interdisciplinaire CNRS USR3078 - Universites Lille I+II, Bures sur Yvette, France Abstract Virulence factors generally enhance a pathogen’s fitness and thereby foster transmission. However, most studies of pathogen fitness have been performed by averaging the phenotypes over large populations. Here, we have analyzed the fitness costs of virulence factor expression by Salmonella enterica subspecies I serovar Typhimurium in simple culture experiments. The type III secretion system ttss-1, a cardinal virulence factor for eliciting Salmonella diarrhea, is expressed by just a fraction of the S. Typhimurium population, yielding a mixture of cells that either express ttss-1 (TTSS-1+ phenotype) or not (TTSS-12 phenotype). Here, we