Membrane fusion as a determinant of the infectibility of cells by vesicular stomatitis virus.

ABSTRACT

When rat embryo fibroblasts (REF) and BHK21 cells were treated with VSV at the same m.o.i., 8- to 10-fold fewer REF were infected than BHK21 cells; REF also showed a similar decrease in the production of progeny virions per cell. When other aspects of the infectious cycle were studied in the two cells, it was found that the time course of virus production was similar in BHK21 cells and REF, virus grown in REF showed the same infectivity in both cell types as virus grown in BHK21 cells, and all REF in a culture could eventually be infected. There was virtually no difference in the binding of VSV to the cells, and REF actually internalized virus at a slightly greater rate than BHK21 cells. Direct fusion of VSV with the plasma membrane of the two cell types resulted in infection of the cells, but did not abolish the difference in infectibility. When this fusion was quantitated using 125I-VSV, BHK21 cells fused 6-fold more virus than REF, a difference that accounts for most of the difference in the infectibility of the two cell types. The results indicate that constituents of the host cell plasma membrane modulate the fusion of VSV.