The membrane-proximal stem region of vesicular stomatitis virus G protein confers efficient virus assembly

In this report, we show that the glycoprotein of vesicular Stomatitis virus (VSV G) contains within its extracellular membrane-proximal stem (GS) a do main that is required for efficient VSV budding, To determine a minimal seq uence in GS that provides for high-level virus,assembly, we have generated a series of recombinant Delta G-VSVs which express chimeric glycoproteins h aving truncated stem sequences. The recombinant viruses having chimeras wit h 12 or more membrane-proximal residues of the G stem, and including the G protein transmembrane-cytoplasmic tail domains, produced near-wild-type lev els of particles. In contrast, viruses encoding chimeras with shorter or no G-stem sequences produced similar to 10- to 20-fold less. This budding dom ain when present in chimeric glycoproteins also promoted their incorporatio n into the VSV envelope. We suggest that the G-stem budding domain promotes virus. release by inducing membrane curvature at sites where virus budding occurs or by recruiting condensed nucleocapsids to sites on the plasma mem brane which are competent for efficient virus budding.