Severe acute respiratory syndrome coronavirus nucleocapsid protein confers ability to efficiently produce virus-like particles when substituted for the human immunodeficiency virus nucleocapsid domain

Wang, Shui-Mei; Chang, Yu-Fen; Chen, Yi-Ming Arthur; Wang, Chin-Tien

We replaced the HIV-1 nucleocapsid (NC) domain with different N-coding sequences to test SARS-CoV nucleocapsid (N) self-interaction capacity, and determined the capabilities of each chimera to direct virus-like particle (VLP) assembly. Analysis results indicate that the replacement of NC with the carboxyl-terminal half of the SARS-CoV N resulted in the production of wild type (wt)-level virus-like particles (VLPs) with the density of a wt HIV-1 particle. When co-expressed with SARS-CoV N, chimeras containing the N carboxyl-terminal half sequence efficiently packaged N. However, the same was not true for the chimera bearing the N amino-terminal half sequence, despite its production of substantial amounts of VLPs. According to further analysis, HIV-1 NC replacement with N residues 2–213, 215–421, or 234–421 resulted in efficient VLP production at levels comparable to that of wt HIV-1, but replacement with residues 215–359, 302–421, 2–168, or 2–86 failed to restore VLP production to wild-type levels. The results suggest that the domain conferring the ability to direct VLP assembly and release in SARS-CoV N is largely contained between residues 168 and 421.