CD46 and infection: Employing bovine viral diarrhea virus (BVDV) encoding an mCherry-E2 fusion protein (BVDVE2-mCherry), being the first genetically labelled member of the family Flaviviridae applicable for the analysis of virus particles, the early events of infection—attachment, particle surface transport, and endocytosis—were monitored to better understand the mechanisms underlying virus entry and their dependence on the virus receptor, bovine CD46.