Nayak, D. P., Hui, E. K., & Barman, S. (2004). Assembly and budding of influenza virus. Virus Research, 106(2), 147-165. doi:10.1016/j.virusres.2004.08.012
This review mainly discusses the biological process of assembly and budding of influenza virus by emphasizing the role that M1 protein plays in the entire virus-host system. Viral particle of influenza is composed of viral envelope, matrix and core (viral ribonucleocapsid vRNP). M1 protein is considered as a bridge between viral core and envelope. During assembly process, M1 is generated at cytosolic ribosomes, and then directed to facilitate vRNP exportation from nucleus to cytoplasm, with the companion of NEP. At this stage, interaction of M1 with cytoplasmic tail and transmembrane domain is critical for the concentration of viral composition at budding site. Also, M1 is thought to be important in budding of the virus by presenting L motif (what is that?).
The author addressed most of major activity in virus replication, while there are some problems that need further examination. The mechanism of the translocation of M1 and vRNP, from nuclear to plasma membrane (assembly site) is still unsolved. Besides viral components like M1 protein, there are a variety of host factors involved in viral budding and most of them are under discovery.
(3D structure of M1 protein, from NCBI)