Related Experiment Video

Updated: Jul 11, 2026

Quantification of Cytosolic vs. Vacuolar Salmonella in Primary Macrophages by Differential Permeabilization
09:25

Quantification of Cytosolic vs. Vacuolar Salmonella in Primary Macrophages by Differential Permeabilization

Published on: July 28, 2015

Flagella facilitate escape of Salmonella from oncotic macrophages

Gen-ichiro Sano1, Yasunari Takada, Shinichi Goto

  • 1Department of Microbiology and Immunology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.

Journal of Bacteriology
|September 18, 2007
PubMed

Insights

Salmonella Typhimurium triggers macrophage cell death called oncosis, allowing bacteria to accumulate and exit host cells using flagella. This mechanism helps the pathogen escape immune surveillance.

Area of Science:

  • Microbiology
  • Immunology
  • Cell Biology

Background:

  • Salmonella Typhimurium is an intracellular parasite causing systemic disease in mice.
  • While Salmonella survival within phagocytes is known, its exit mechanism from host cells is poorly understood.

Purpose of the Study:

  • To investigate the mechanism of intracellular Salmonella Typhimurium exit from host macrophages.

Main Methods:

  • Induction of macrophage oncosis by Salmonella Typhimurium.
  • Characterization of oncotic macrophages (OnMphis) using TUNEL assay and F-actin staining.
  • Observation of intracellular Salmonella motility and exit using microscopy.

Main Results:

  • Salmonella Typhimurium induces oncosis, a form of programmed cell death, in infected macrophages.
  • Oncotic macrophages exhibit cell swelling, are TUNEL-negative, and lack F-actin.
  • Intracellular Salmonella retain motility via flagella within the intact plasma membrane of OnMphis.
  • Salmonella flagella are essential for the intermittent exit of bacteria from OnMphis.

Conclusions:

  • Salmonella Typhimurium utilizes macrophage oncosis as a host cell exit strategy.
  • Flagellar motility plays a crucial role in Salmonella escape from dying macrophages.

More Related Videos

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages10:33

Isolation of Salmonella typhimurium-containing Phagosomes from Macrophages

Published on: October 25, 2017

High-throughput Assay to Phenotype Salmonella enterica Typhimurium Association, Invasion, and Replication in Macrophages11:10

High-throughput Assay to Phenotype Salmonella enterica Typhimurium Association, Invasion, and Replication in Macrophages

Published on: August 11, 2014

Related Concept Videos

Colonisation of Pathogens01:25

Colonisation of Pathogens

Pathogen colonization of host tissues is a critical step in the development of infectious diseases. Various pathogenic microorganisms, including bacteria, fungi, viruses, and protozoa, have evolved complex strategies to attach to, invade, and persist within host environments. These mechanisms enable pathogens to establish infections, evade immune responses, and resist antimicrobial treatments.Attachment to Host CellsIn bacteria, colonization typically begins with adherence to host epithelial...
Flagella and Motility in Bacteria01:18

Flagella and Motility in Bacteria

Flagella are specialized, thread-like structures that extend from a bacteria's cell envelope. They play a crucial role in motility and chemotaxis. Their structural organization and functioning exemplify sophisticated biological engineering, enabling bacterial survival and adaptability in diverse environments.Structure of the FlagellumA bacterial flagellum consists of three key components: the filament, the hook, and basal body. The filament, a long, helical structure composed of repeating...
Cancer Cell Migration through Invadopodia01:35

Cancer Cell Migration through Invadopodia

Invadosome is a broad category of cell surface structures with proteolytic activity that  degrades the extracellular matrix (ECM). Invadosomes are present in normal cell types, including macrophages, endothelial cells, and neurons, as well as tumor cells. Although the macrophage podosomes and tumor cell invadopodia are classified as invadosomes, they have different structures, molecular pathways, and functions. Podosomes are short structures that last for a few minutes. However, invadopodia can...
Immune Surveillance by NK Cells and Phagocytes01:25

Immune Surveillance by NK Cells and Phagocytes

Immune surveillance is an integral part of the innate immune system, involving the continuous monitoring of peripheral tissues to detect and respond to pathogens, infected cells, or cancerous cells. This surveillance is conducted primarily by natural killer (NK) cells and phagocytes, which employ distinct but complementary mechanisms to identify and eliminate threats.
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...
Chemotaxis in E. coli01:27

Chemotaxis in E. coli

Chemotaxis in Escherichia coli is a sensory-driven motility mechanism that enables bacteria to navigate chemical gradients, moving toward beneficial environments while avoiding harmful conditions. This process relies on a signal transduction system integrating external chemical cues with flagellar motor control.Chemoreceptors and Signal DetectionE. coli detects chemical gradients through methyl-accepting chemotaxis proteins (MCPs), which are membrane-bound chemoreceptors that sense attractants...