EFFECT OF GLYCOSAMINOGLYCANS AND PEG ON FUSION OF SENDAI VIRUS WITH PHOSPHATIDYLSERINE VESICLES

The fusion of Sendai virus with phosphatidylserine vesicles was monito red by a pyrene-phosphatidylcholine fluorescence assay. A strong influ ence of pH and ionic strength on the extent of fusion was observed. Th e negatively-charged polymers (dextran sulfate, heparin and chondroiti n sulfate) inhibited the ability of the viruses to fuse with the lipos omes. The extent of inhibition, for a given amount (w/v) of the polyme rs, was the greatest for dextran sulfate followed by heparine and chon droitin sulfate. The extent of inhibition depended on the pH and ionic strength of the solution; the lower the pH of the solution, the more effective the fusion inhibition by the polymers. The molecular weight of dextran sulfate (DS) influenced the inhibition effect, i.e., DS wit h higher molecular weight exhibited a stronger inhibition effect. The presence of sodium sulfate, even in excess concentration, had no inhib itory effect on fusion. On the other hand, PEG had an opposite effect on fusion compared to the negatively-charged polymers, and it decrease d their inhibition effect when both were present in the same media. It is concluded that the inhibition of the fusion activity of Sendai vir us results from the adherence of negatively-charged polymers to the vi rus surface preventing close contacts between the virus and liposome s urface.