Sendai virus particle production: a more detailed role of F and HN through, namely, their association with M.

The Paramyxovirus membrane associated proteins are composed of two integral membrane glycoproteins, HN (H, G) and F, and of a matrix protein (M) carpeting the membrane inner layer. For Sendai virus (SeV), F and M have been proposed to form a complex at the endoplasmic reticulum that further migrates to the cell periphery where it represents a nucleation site for viral assembly completion (Essaidi-Laziosi et al., 2013). HN is recruited in the assembly complex once expressed at the cell surface. In contrast to F and M, HN appears dispensable for virus particle production. However, upon F suppression, concomitant HN suppression restricts viral particle production much more severely than F suppression alone, suggesting that HN plays a role as well. In this study, we demonstrate that the transmembrane and cytoplasmic regions of F are sufficient to promote virus particle production and incorporation of a foreign protein in viral particles. We further identify in the F cytoplasmic tail the site of interaction with M. We next confirm HN participation in viral particle production and we provide genetic evidence for a participation of M in the process. We finally derive observations that may provide a mechanism by which the viral C protein participates in viral particle production by mediating HN-M interaction.