from Justin A. Roby, Anneke Funk, and Alexander A. Khromykh writing in Molecular Virology and Control of Flaviviruses:
The replication and assembly of Flaviviruses are complex procedures, which require the efficient coordination of a number of different steps. These stages are highly organized temporally and spatially in the infected cell and require the virus-induced establishment of host-derived membrane structures. Flavivirus RNA structures, non-structural proteins and host factors actively participate in the replication of genomic RNA within vesicle packets (VP). Progeny (+) strand RNA exits the VP pore and is incorporated into nucleocapsids by the capsid protein. Nucleocapsids are then presumably transported into the lumen of the endoplasmic reticulum at sites directly opposed to the VP pore during formation of the prM-E studded lipid envelope. These immature virions are trafficked to the Golgi network in individual vesicles for glycoprotein maturation and furin-directed prM cleavage. Mature virions (with associated, cleaved prM) are then secreted into the extracellular milieu.
Further reading: Molecular Virology and Control of Flaviviruses