A new method for quantitative analysis of M13 bacteriophage by atomic force microscopy

Area of Science:

• Microbiology
• Nanotechnology
• Biophysics

Background:

• Accurate virus quantification is crucial for research, with plaque assays being the traditional method.
• Plaque assays are time-consuming, complex, and unsuitable for phages that do not form visible plaques.
• There is a need for rapid, effective, and versatile methods for virus titer determination.

Purpose of the Study:

• To establish a novel method for rapid and effective virus quantification.
• To overcome the limitations of traditional plaque assays, especially for difficult-to-plaque phages.
• To enable visualization of virus particles during titer determination.

Main Methods:

• Utilized atomic force microscopy (AFM) for direct observation and counting of M13 phages.
• Employed mathematical calculations based on AFM counting results for titer determination.
• Compared the new method with traditional plaque assay in terms of speed and applicability.

Main Results:

• The combined AFM and mathematical calculation method allowed for phage titer determination within hours.
• The method provides visualization of phage particles, aiding in quantitative assessment.
• This approach shows potential for quantifying phages that do not form apparent plaques on solid media.

Conclusions:

• A new, rapid, and visual method for virus titer determination using AFM has been successfully established.
• This technique significantly reduces the time required compared to conventional plaque assays.
• The method holds promise for quantitative virus assessment, particularly for challenging phage types.