A mathematical model for temperature effects on virus-mediated cell fusion

Syncytia are formed by fusion of multiple cells into a multi-nucleated cell body. Viral-induced syncytia formation is used by certain viruses to propagate without leaving the cell. The ability to propagate without leaving the cell allows viruses to enhance replication and evade some of the host's immune responses. Currently, it is not known how temperature affects syncytia formation rate. This study uses a cell-to-cell fusion mathematical model to analyze data from previously published cell-cell fusion assays of HIV and SARS-CoV-2 at various temperatures. Parameters were estimated via minimization of squared residuals, with uncertainties assessed through bootstrapping. While we find differences in temperature dependence in the two viruses, due to limited temporal and temperature measurements, we are unable to draw definitive conclusions. However, given a more comprehensive experimental data set, the methodology proposed here allows for quantitative comparison of temperature dependence of syncytia formation in different viruses.