An Assay to Quantify the Binding of Human Norovirus VLPs to Intestinal Bacteria

Take a tube containing a suspension of human intestinal bacteria.

Add human norovirus virus-like particles, or VLPs. The VLPs contain an intact viral capsid but lack genomic RNA, rendering them non-infectious to humans.

During incubation, the VLP capsid proteins bind to specific carbohydrates expressed on the bacterial surface, forming VLP-bacteria complexes.

Centrifuge to pellet the complexes and discard the unbound VLPs.

Introduce a protein-containing blocking solution to block non-specific antibody binding sites, reducing background staining in subsequent steps.

Add fluorescently labeled VLP-specific antibodies and incubate.

The antibodies bind to their target sites on the VLP capsid, labeling the VLP-bacteria complexes.

Centrifuge to pellet the complexes. Discard unbound antibodies and resuspend the pellet in a flow cytometry buffer.

Using a flow cytometer, detect fluorescence signals emitted by VLP-bacteria complexes, allowing for the quantification of the percentage of bound bacteria in the sample.