TY - JOUR T1 - Attenuated Salmonella Typhimurium Lacking the Pathogenicity Island-2 Type 3 Secretion System Grow to High Bacterial Numbers inside Phagocytes in Mice A1 - Grant, Andrew J. A1 - Morgan, Fiona J. E. A1 - McKinley, Trevelyan J. A1 - Foster, Gemma L. A1 - Maskell, Duncan J. A1 - Mastroeni, Pietro Y1 - 2012/12/06 N2 - Author Summary High quality science has been published concerning the dynamics of infectious disease spread through communities of people or animals, but less work has been done to understand infectious disease dynamics within the host. Many conclusions about how infectious agents work are based on experiments in isolated monocultures of cells or in somewhat crude experiments in whole animals. Understanding this complex process in whole animals is the next major challenge for infectious disease biologists, and is required if intervention strategies to prevent and cure infectious diseases are to be improved and targeted effectively. Bacteria of the species Salmonella enterica are a threat to public health, causing a wide range of life-threatening diseases in humans and animals world-wide. In vitro cell experiments and inference from measuring net growth kinetics in mouse organs suggest that intracellular replication of S. enterica requires proteins delivered by the Salmonella pathogenicity island 2 (SPI-2) type 3 secretion system (T3SS) and that mutants in SPI-2 cannot replicate efficiently intracellularly. However, by observing directly infection dynamics at the single-cell level in vivo, we show that SPI-2 T3SS mutants can replicate to high intracellular densities in phagocytes in the organs of infected animals, but appear unable to leave infected cells. JF - PLOS Pathogens JA - PLOS Pathogens VL - 8 IS - 12 UR - https://doi.org/10.1371/journal.ppat.1003070 SP - e1003070 EP - PB - Public Library of Science M3 - doi:10.1371/journal.ppat.1003070 ER -