Recombinant Merkel Cell Polyomavirus (MCPyV) Virion Preparation: A Technique to Produce High-titer Recombinant MCPyV Virion

- Merkel cell polyomavirus, or MCPyV, is a double-stranded DNA oncovirus with a circular genome that causes merkel cell carcinoma, a type of skin cancer. To prepare MCPyV virions, first, treat an adherent culture of packaging cells with a cocktail containing a transfection agent, the viral genome, and two expression plasmids encoding proteins required for promoting viral replication.

During incubation, the transfection reagent forms lypoplexes with the plasmids, facilitating their delivery into the packaging cells. Once inside the nucleus, the cell machinery allows the expression of the viral and plasmid genomes. The expression plasmids encode large-tumor antigen and small-tumor antigen proteins. These proteins translocate to the nucleus and drive viral DNA replication. Subsequently, the viral genome encodes structural capsid proteins. These proteins move into the nucleus and help in the assembly of recombinant virions.

Next, harvest the cultured cells. Treat them with a solution containing detergent and DNase. The detergent lyses the cells to release the viruses. DNase degrades any free plasmid DNA from the suspension. Centrifuge to separate cellular debris in the pellet. Load the