ROLE OF HYDROPHOBIC INTERACTIONS IN THE FUSION ACTIVITY OF INFLUENZA AND SENDAI VIRUSES TOWARDS MODEL MEMBRANES

We have studied the role of hydrophobic interactions in the fusion act ivity of two lipid enveloped viruses, influenza and Sendai. Using the fluorescent probe ANS (1-aminonaphtalene-8-sulfonate) we have shown th at low-pH-dependent influenza virus activation involves a marked incre ase in the viral envelope hydrophobicity. The effect of dehydrating ag ents on the fusion activity of both viruses towards model lipid membra nes was studied using a fluorescence dequenching assay. Dehydrating ag ents such as dimethylsulfoxide and dimethylsulfone greatly enhanced th e initial rate of the fusion process, the effect of dimethylsulfone do ubling that of dimethylsulfoxide. The effect of poly(ethylene glycol) on the fusion process was found to be dependent on the polymer concent ration and molecular weight. In general, similar observations were mad e for both viruses. These results stress the importance of dehydration and hydrophobic interactions in the fusion activity of influenza and Sendai viruses, and show that these factors may be generally involved in membrane fusion events mediated by many other lipid enveloped virus es.