Related Experiment Video
Updated: Dec 7, 2025
Measuring Bacterial Load and Immune Responses in Mice Infected with Listeria monocytogenes
Published on: August 9, 2011
Internalization Assays for Listeria monocytogenes
Andreas Kühbacher1, Pascale Cossart2, Javier Pizarro-Cerdá3
1Farco-Pharma GmbH, Cologne, Germany.
Insights
This study details methods for measuring Listeria monocytogenes invasion into host cells. Assays include the gentamicin protection assay and immunofluorescence microscopy for quantifying bacterial internalization.
Area of Science:
- Microbiology
- Cell Biology
- Infectious Diseases
Background:
- Listeria monocytogenes is a key intracellular pathogen model.
- Host cell invasion is a critical step in Listeria pathogenesis.
- Quantifying bacterial internalization is essential for studying host-pathogen interactions.
Purpose of the Study:
- To describe and compare methods for quantifying Listeria monocytogenes internalization into host cells.
- To provide detailed protocols for two distinct invasion assays.
- To enable researchers to select appropriate methods for their studies.
Main Methods:
- Gentamicin protection assay: quantifies viable intracellular bacteria via colony-forming units.
- Immunofluorescence microscopy: visualizes and quantifies intracellular bacteria using fluorescent antibodies.
- Comparison of assay performance for medium- to high-throughput analysis.
Main Results:
- Both gentamicin protection assay and immunofluorescence microscopy effectively quantify Listeria monocytogenes invasion.
- Immunofluorescence offers higher throughput capabilities for invasion assays.
- Assays can be used independently or in combination for comprehensive analysis.
Conclusions:
- Standardized assays are crucial for reproducible measurement of Listeria monocytogenes host cell invasion.
- A combination of methods can provide robust data on bacterial internalization.
- These methods facilitate research into Listeria pathogenesis and host-pathogen interactions.
Abstract:
Listeria monocytogenes is a model intracellular pathogen that can invade the cytoplasm of host mammalian cells. Cellular invasion can be measured using standard techniques, such as the classical gentamicin protection assay, based on the quantification of colony-forming units from lysates of infected cells. In addition, there are methods based on immunofluorescence microscopy which allow for assaying invasion in a medium- to high-throughput manner. In the following sections, we detail two different assays that can be used alone or in combination to quantify the internalization of L. monocytogenes in host cells.
