A comparative study of the effect of dextran sulfate on the fusion and the in vitro replication of influenza A and B, Semliki Forest, vesicular stomatitis, rabies, Sendai, and mumps virus.

The effect of dextran sulfate on the fusion of a series of enveloped viruses, bearing specifically different fusion proteins, was investigated. The fusion with model- and with biological membranes was monitored by an R18 fluorescence-dequenching fusion assay. Dextran sulfate strongly suppresses the fusion of orthomxyo- (influenza A (H1N1 and H3N2 subtypes) and influenza B), of toga- (Semliki Forest virus), and of rhabdoviruses (vesicular stomatitis and rabies virus). The fusion of the paramyxo-viruses Sendai and mumps was not significantly affected by the anionic polysaccharide. The response to dextran sulfate was virus-specific, and identical for the different members of one virusfamily, bearing the same fusion protein. It was shown that dextran sulfate attaches with high affinity to the viruses studied, but not to erythrocytes. The anionic polymer appears to attach to the fusion epitope of the viral membrane. The inhibition of virus replication in vitro shows a remarkable correlation with the observed anti-fusion effects of dextran sulfate.