EXPRESSION OF ADDITIONAL GENES IN A VECTOR DERIVED FROM A MINIMAL RNAVIRUS

Previous studies have shown that expression of the vesicular stomatiti s virus (VSV) glycoprotein (G) from a Semliki Forest virus (SFV) RNA r eplicon results in the production of propagating infectious particles that we call minimal viruses. These minimal viruses consist of vesicle s containing VSV G protein that bud from the plasma membrane and trap the infectious SVF, G RNA, but they do not contain other viral structu ral proteins. The cell binding and membrane fusion activity of the VSV G protein allow minimal viruses to propagate in tissue culture cells. To determine if these minimal viruses could be used to express foreig n genes, we added a second SFV promoter and a multiple cloning site do wnstream of the VSV G gene. We report here expression of three differe nt proteins from this modified, minimal virus vector. Although express ion of each foreign, unselected gene was lost rapidly from the vector upon passaging, it was possible after the initial transfection to deri ve stocks of infectious particles that could be used to infect multipl e additional cultures and transfer protein expression efficiently. Whe n cells were infected with these minimal viruses, host protein synthes is was shut off and the foreign protein and VSV G proteins were the ma jor proteins expressed in the infected cells. Both were expressed at s imilar levels and accumulated to about 1-2% of total cell protein. (C) 1996 Academic Press, Inc.