Modeling of the Initial Stage of Fusion of Influenza Virus with Liposomes

The initial stage of viral infection - fusion of viral and target cell membranes - is still a nontrivial system for analysis due to a large number of parameters affecting this process, as well as due to small size of the fusion region, which for a long time made the fusion process difficult for experimental study. A number of recently published papers allowed us to determine features of the geometric structure of fusing membranes, insertion of fusion proteins into the membrane monolayers, and to determine the dependence of fusion efficiency on the membrane composition. Relying on the latest experimental data, on the basis of the theory of elasticity of lipid membranes, we built a fusion model that quantitatively describes these experimental results and in particular, makes it possible to calculate the energy barrier necessary to ensure close contact of fusing membranes, which determines the fusion efficiency. This allows us to adapt the existing fusion theory to these results and for the first time to obtain a quantitative agreement of the effect of the composition of the target cell membrane on the height of the fusion energy barrier.