Figure 2.

Schematic description of the model for the switching from R5 to X4 viral phenotype. Schematic description of the model for the switching from R5 to X4 viral phenotype. Naïve T-cells, U, are generated at constant rate N_U and removed at rate δ^U. They give birth to differentiated, uninfected T-cells, T. These in turn are removed at constant rate δ^T and become infected as they interact with the virus. Infected T-cells, I, die at rate δ^I and contribute to the budding of viral particles, V, that are cleared out at rate c. As soon as the X4 phenotype arise, the production of the TNF starts, proportional to the X4 concentration and contribute to the clearance of naïve T-cells, via the parameter.