Internalization assays for Listeria monocytogenes

Area of Science:

• Microbiology and Immunology
• Cell Biology
• Bacterial Pathogenesis

Background:

• Listeria monocytogenes is a well-established intracellular pathogen.
• Understanding host cell invasion mechanisms is crucial for studying bacterial pathogenesis.
• Quantifying bacterial internalization is essential for evaluating infection dynamics.

Purpose of the Study:

• To describe and compare two distinct assays for quantifying host cell invasion by Listeria monocytogenes.
• To provide detailed protocols for both the gentamicin protection assay and immunofluorescence-based methods.
• To enable researchers to select appropriate methods for their specific research needs.

Main Methods:

• Classical gentamicin protection assay: involves lysing infected cells and quantifying viable intracellular bacteria via colony-forming units (CFUs).
• Immunofluorescence microscopy-based assays: allow for medium- to high-throughput assessment of bacterial internalization.
• Combination of assays: utilizing both methods for a comprehensive analysis of invasion.

Main Results:

• Both the gentamicin protection assay and immunofluorescence methods effectively quantify Listeria monocytogenes invasion.
• Immunofluorescence offers advantages for medium- to high-throughput screening.
• The choice of assay depends on experimental scale and specific research questions.

Conclusions:

• Accurate quantification of Listeria monocytogenes internalization is achievable through established microbiological techniques.
• Researchers can select between CFU-based or microscopy-based assays, or combine them, for robust invasion studies.
• These methods support further investigation into host-pathogen interactions and the development of therapeutic strategies.