Schematic representation of the tetracistronic trVLP system
p0 cells are transfected with a plasmid encoding a tetracistronic minigenome which, in addition to a reporter gene, also contains the filoviral genes responsible for the production of virus particles. In addition, plasmids are cotransfected that encode the viral RNP proteins, which are necessary for viral genome replication and transcription. This leads to the replication and transcription of the minigenomes, and as a result of the expressed viral proteins to the formation of virus-like particles which can take up minigenomes and infect new cells (p1 cells). These have also been pre-transfected with plasmids for the RNP proteins, so that in p1 cells the minigenome is replicated and transcribed again. The resulting reporter activity can be measured and allows conclusions on the efficiency of all aspects of the viral replication cycle. © 2014 American Society of Microbiology. Reproduced from Watt et al. 2014, J. Virol. 88(18):10511 with kind permission of the American Society of Microbiology.