FUSION ACTIVITY OF AFRICAN SWINE FEVER VIRUS TOWARDS TARGET MEMBRANES- LIPID DEPENDENCE AND EFFECT OF DEHYDRATING AGENTS

Fusion of African swine fever virus (ASFV) with model membranes was mo nitored by a fluorescence dequenching assay. ASFV was able to fuse wit h liposomes of various compositions. Fusion was more extensive with li posomes made of negatively charged phospholipids, and reduced in the p resence of the neutral phospholipid phosphatidylcholine (PC). Fusion a ctivity of ASFV was pH-dependent, the extent of fusion increasing with decreasing pH for all target membranes. These results are consistent with the in vivo characteristics of fusion of ASFV with the endosome m embrane. An increase in fusion activity was obtained with dehydrating agents, similarly to what occurs with other lipid-enveloped viruses. D ehydrating agents such as dimethylsulfoxide and dimethylsulfone greatl y enhanced fusion, the effect of dimethylsulfone being more pronounced than that of dimethylsulfoxide. Poly(ethylene glycol) also potentiate d ASFV fusion activity, and the effect of this polymer was found to be dependent on its molecular weight. These results stress the importanc e of dehydration and hydrophobic interactions on the early events of v iral penetration into target cells.