Efficient particle production by minimal gag constructs which retain the carboxy-terminal domain of human immunodeficiency virus type 1 capsid-p2 anda late assembly domain

The human immunodeficiency virus type 1 (HIV-1) Gag precursor Pr55(gag) by itself is capable of assembling into retrovirus-like particles (VLP). In th e present study, we attempted to identify the minimal Gag sequences require d for the formation of VLP. Our results show that about 80% of Pr55(gag) ca n be either deleted or replaced by heterologous sequences without significa ntly compromising VLP production. The smallest chimeric molecule still able to efficiently form VLP was only about 16 kDa. This minimal Gag construct contained the leucine zipper domain of the yeast transcription factor GCN4 to substitute for the assembly function of nucleocapsid (NC), followed by a P-P-P-P-Y motif to provide late budding (L) domain function, and retained only the myristylation signal and the C-terminal capsid-p2 domain of Pr55(g ag). We also show that the L domain function of HIV-1 p6(gag) is not depend ent on the presence of an active viral protease and that the NC domain of P r55(gag) is dispensable for the incorporation of Vpr into VLP.