A Fluorescently Labeled Marburg Virus Glycoprotein as a New Tool to Study Viral Transport and Assembly

The single surface glycoprotein (GP) of filoviruses is indispensable for recognition of its cellular receptor and infection of target cells. To study the intracellular trafficking of GP by using live-cell imaging, the mucin-like domain of Marburg virus (MARV) GP was replaced by the fluorophore mCherry (GPMLD-mCherry). Intracellular distribution, surface transport, and recruitment of GPMLD-mCherry into virus-like particles were similar to observations for wild-type GP. Using reverse genetics, we generated a recombinant MARV expressing GPMLD-mCherry (recMARV MARVGPMLD-mCherry). Time-lapse microscopy of recMARV MARVGPMLD-mCherry-infected cells revealed that GPMLD-mCherry-positive vesicles were transported to the cell surface in a tubulin-dependent manner. Moreover, dual-color live-cell imaging revealed cotransport of GPMLD-mCherry and VP40 and their colocalization at the plasma membrane. In this proof-of-concept study we showed that the newly developed GPMLD-mCherry is a promising tool to elucidate intracellular trafficking and assembly pathways of MARV.