Attenuated Salmonella Typhimurium Lacking the Pathogenicity Island-2 Type 3 Secretion System Grow to High Bacterial Numbers inside Phagocytes in Mice

PLoS Pathogens

Andrew J. Grant¹  Pietro Mastroeni¹  Duncan J. Maskell¹  Fiona J. E. Morgan¹  Gemma L. Foster¹  Trevelyan J. McKinley¹ 

[1] Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom

关键词: Salmonellosis;    Intracellular pathogens;    Phagocytes;    Spleen;    Salmonella;    Liver;    Bacterial genetics;    Salmonella enterica;   

DOI  :  10.1371/journal.ppat.1003070

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Intracellular replication within specialized vacuoles and cell-to-cell spread in the tissue are essential for the virulence of Salmonella enterica. By observing infection dynamics at the single-cell level in vivo, we have discovered that the Salmonella pathogenicity island 2 (SPI-2) type 3 secretory system (T3SS) is dispensable for growth to high intracellular densities. This challenges the concept that intracellular replication absolutely requires proteins delivered by SPI-2 T3SS, which has been derived largely by inference from in vitro cell experiments and from unrefined measurement of net growth in mouse organs. Furthermore, we infer from our data that the SPI-2 T3SS mediates exit from infected cells, with consequent formation of new infection foci resulting in bacterial spread in the tissues. This suggests a new role for SPI-2 in vivo as a mediator of bacterial spread in the body. In addition, we demonstrate that very similar net growth rates of attenuated salmonellae in organs can be derived from very different underlying intracellular growth dynamics.

【 授权许可】

CC BY