Analysis of severe acute respiratory syndrome coronavirus structural proteins in virus‐like particle assembly

Nakauchi, Mina; Kariwa, Hiroaki; Kon, Yasuhiro; Yoshii, Kentaro; Maeda, Akihiko; Takashima, Ikuo

SARS‐CoV has four major structural proteins: the N, S, M, and E proteins. To investigate the mechanism of SARS‐CoV assembly, we cloned the genes encoding these four proteins into the eukaryotic expression vector pCAGGS and transfected them into 293T cells. When all four expression vectors were co‐transfected VLP formed, as confirmed using electron microscopy. Using a rabbit polyclonal antibody specific to the N protein, N‐protein‐containing particles similar in size to the VLP were also observed by immunoelectron microscopy, indicating that the VLP contained the N protein. Co‐immunoprecipitation analyses demonstrated an interaction between the N and M proteins, suggesting that N protein binds directly to M protein to be incorporated into VLP.