Measles virus M and F proteins associate with detergent-resistant membrane fractions and promote formation of virus-like particles.

Assembly and release of particles comprise a late step in virus-host cell interactions. Though it may share major biological properties with its orthologues in related viruses, trafficking and oligomerization of the matrix (M) protein of Measles virus (MV) and its relative contribution to assembly and budding of particles from particular host cells have not been addressed in more detail. Plasmid-driven expression of authentic and mutant M proteins revealed that the amino acid at position 89, an important adaptation determinant for growth of attenuated strains in Vero cells, influences the electrophoretic mobility but not the intracellular distribution of M proteins, nor their ability to oligomerize or migrate as a doublet band in SDS-PAGE. M proteins were found to co-float with detergent-resistant membrane fractions (DRM) and this was enhanced upon co-expression of the F protein. In contrast to their DRM association, the ability of M proteins to promote release of virus-like particles (VLPs) was not affected by the presence of F proteins, which on their own also efficiently promoted VLP production. Thus, DRM recruitment of MV F and M proteins and their ability to drive particle formation are not correlated.