Plaque assay for murine norovirus.

Area of Science:

• Virology
• Cell Biology

Background:

• Murine norovirus (MNV) is the only norovirus that replicates efficiently in cell culture.
• MNV infection causes cell lysis and cytopathic effect (CPE) in susceptible cells like murine macrophages.
• Accurate quantification of infectious viral particles is crucial for research and diagnostics.

Purpose of the Study:

• To describe a detailed plaque assay protocol for quantifying infectious MNV particles.
• To provide a reliable method for determining viral load in various sample types.
• To highlight the advantages of plaque assays over other viral quantification methods.

Main Methods:

• Preparation of 10-fold serial dilutions of MNV samples.
• Inoculation of permissive RAW 264.7 murine macrophage cell monolayers.
• Overlaying cells with agarose to facilitate localized viral spread and plaque formation.
• Staining cells with dyes (e.g., neutral red) to visualize plaques.
• Calculating plaque-forming units (PFU) based on plaque counts.

Main Results:

• The described plaque assay protocol effectively quantifies infectious MNV particles.
• Plaque formation is a direct result of MNV-induced cell lysis.
• The assay allows for the enumeration of infectious viral particles, represented as PFU.

Conclusions:

• The plaque assay is a reliable and effective method for titering infectious MNV.
• This protocol enables accurate quantification of MNV in biological and environmental samples.
• Plaque assays offer a direct measure of viral infectivity, unlike methods such as qRT-PCR.