ENHANCEMENT OF HUMAN PARAINFLUENZA VIRUS-INDUCED CELL-FUSION BY PRADIMICIN, A LOW-MOLECULAR-WEIGHT MANNOSE-BINDING ANTIBIOTIC

Oligosaccharides, especially mannose residues, expressed on the cell s urface, are thought to be important for virus-induced membrane fusion. We examined the effect of mannose-binding compounds, pradimicin deriv ative BMY-28 864 (PRM) and concanavalin A (Con A), on cell fusion of h uman parainfluenza type 2 virus (hPIV2)-infected HeLa cells. Syncytium formation of hPIV2-infected HeLa cells was suppressed in the presence of Con A. On the other hand, PRM enhanced cell fusion of hPIV2 infect ed HeLa cells. These effects were blocked by addition of mannose-rich mannan. However, PRM shows little effect on virus growth and the expre ssion of viral glycoproteins on the cell surface in hPIV2-infected HeL a cells. Fluorescein-isothiocyanate-labeled pradimicin and Con A bound to both uninfected and hPIV2-infected mononuclear cells, indicating t hat these compounds have an affinity to several cellular component(s). In contrast to Con A, PRM had little affinity to the viral glycoprote ins. It is inferred from these results that the enhancement of hPIV2-i nduced cell fusion is probably due to the interaction between PRM and cellular component(s).