In Vitro Replication Assay for Merkel Cell Polyomavirus (MCPyV)

Merkel cell polyomavirus (MCPyV) genomes are clonally integrated in tumor cells of ∼95% of all Merkel cell carcinoma (MCC) cases. The virus is highly prevalent; however, where the virus persists and which cell types are permissive for MCPyV replication is still unknown. As a consequence, very little information is available about the life cycle and no fully permissive in vitro replication system has been established. Recently, semi-permissive replication systems based on wild-type MCPyV genomes recovered from the skin of healthy donors or synthetic MCPyV genomes constructed from consensus sequences have been established. The transfection of this intramolecular re-circularized MCPyV DNA into some human cell lines recapitulates efficient DNA replication of the viral genome, viral gene expression as well as moderate levels of virus particle formation. However, serial transmission of infectious virus is still restricted in these cells. © 2015 by John Wiley & Sons, Inc.