Acts as a transcription anti-termination factor immediately after transcription initiation, but does not affect transcription elongation. This function has been found to be dependent on the formation of an RNA secondary structure at the transcription start site of the first gene (By similarity). Homooligomer. Tightly bound in the nucleocapsid. Phosphorylated by host. Phosphorylation negatively regulates the transcription activation (By similarity). Belongs to the filoviridae transcriptional activator VP30 family.