NUCLEOCAPSID-LIKE AND VIRUS-LIKE PARTICLES ASSEMBLE IN CELLS INFECTEDWITH RECOMBINANT BACULOVIRUSES OR VACCINIA VIRUSES EXPRESSING THE M-SEGMENTS AND THE S-SEGMENTS OF HANTAAN-VIRUS

The formation of Hantaan (HTN) virus nucleocapsid-like structures (NLS ) or virus-like particles (VLP) from expressed gene products was inves tigated in two eukaryotic systems. Baculovirus expression of the HTN v irus Small segment (S), which encodes the viral nucleocapsid protein, resulted in assembly of NLS inside infected insect cells. The NLS and authentic ribonucleocapsids, prepared by detergent disruption of HTN v irions, had similar sedimentation characteristics and morphologies, an d were recognized by HTN virus N-specific antibodies. Co-expression of S and the medium segment (M), which encodes the two viral envelope gl ycoproteins (G1 and G2), did not efficiently generate VLP in the bacul ovirus-insect cell system, but VLP were observed in lysates and supern atants of cells infected with a recombinant vaccinia virus co-expressi ng HTN virus M and S. The VLP sedimented in sucrose to densities consi stent with HTN virions, and some of them bore a striking resemblance t o Hantaan virions when examined by immunoelectron microscopy.