FIG 1.

Model of viral and immune dynamics considering target cells (T), infected cells (I), virions (V), and CD8⁺ T cells (E). The functional profile of the CD8⁺ T cell response is denoted by the frequencies of CD8⁺ T cells capable of (i) inhibiting viral entry (f_e), (ii) impairing viral replication (f_r), and killing infected cells (f_k). In a fully functional CD8⁺ T cell response, all CD8⁺ T cells would express all different effector functions considered. With a dysfunctional profile, not all effector functions are expressed by all CD8⁺ T cells. The functional profile of the CD8⁺ T cell response influences the infection rate (β), the viral production rate (ρ), or the death rate of infected cells by the additional killing term kf_kE, respectively, as schematically indicated. A detailed description of the model and the individual parameters is given in Materials and Methods.