[3P-54] Structural insight into the interaction of the Sendai virus C protein with Alix stimulating the ESCRT-dependent viral budding
Human parainfluenza virus type I (hPIV1) is a respiratory pathogen affecting in young children, immunocompromised patients, and the elderly, with no available vaccines or antiviral drugs. Sendai virus (SeV), a murine counterpart of hPIV1, has been extensively studied to determine the molecular and biological properties of hPIV1. These viruses possess a multifunctional accessory protein, known as the C protein, which is essential for stimulating viral reproduction, however, its role in budding remains controversial. In the present study, the crystal structure of the C-terminal half of the SeV C protein (Y3) associated with the Bro1 domain of Alix, a component of a cell membrane modulating machinery ESCRT, was elucidated. Based on the structure, we designed mutated C proteins with different binding affinity to Alix, and showed that this interaction is vital for the SeV budding, which enhances the ESCRT-dependent viral budding. These findings provide new insights into the development of a new antiviral drugs against hPIV1.