Table 1. Biologic parameters for modeling of the CD4+ T lymphocyte compartment.
| Parameter | Definition | Value |
| NCD4 | Total body CD4+ T lymphocytes at steady state (before SIV infection) | 3.5×109 cells [44] |
| δCD4R | Death rate of resting CD4+ T lymphocytes | 3×10−3/day [45] |
| ActCD4fract | Fraction of activated CD4+ T lymphocytes at steady-state before SIV infection | 4.5×10−2 [44], [46] |
| ActCD4 | Constant rate of activation of naïve CD4+ T lymphocytes | 1.2×10−2/day* |
| βCD4 | Rate of new naïve CD4+ T lymphocyte production | 4.75×107 cells/day** |
| ActCD4life | Lifespan of an activated CD4+ T lymphocyte | 4 days [47] |
| S | Number of temporal subdivisions of the lifespan utilized for the simulation | 50 |
| Revert | Reversion rate of activated CD4+ T lymphocytes returning to resting | 5×10−2 [36], [51] |
| IIni | Initial number of SIV-infected activated CD4+ T lymphocytes | Set at 100 cells |
| Eclipse | Time before an infected CD4+ T lymphocyte starts to release virions | 2 days [25], [33] |
| Virion Prod | Maximum virus that an infected CD4+ T lymphocyte can produce | 2×104 virions/day [48], [64] |
| R0 | Basic reproductive number (number of new infected cells from one productivelyinfected cell in absence of immune response) | 10 cells*** |
| κ | Factor for CTL killing of infected cells relative to stage of cell infection | 5×10−9/cell/day [29] |
| δV | Lifespan of a free virion | 0.5 hour [60], [61] |
The parameters utilize for modeling CD4+ T lymphocyte turnover and infection using the NPP assumption are listed. For the PP assumption, activated cells were committed to 8 divisions with the same kinetics as CTLs (see Table 2).
Derived constant based on biologically observed steady state value and estimated loss rate of activated cells (see Supplemental Methods). For the programmed proliferation assumption (PP), the value is 1.9×10−4/day.
Derived constant based on biologically observed steady state value and estimated loss rate of total body CD4+ T lymphocytes (see Supplemental Methods). For the programmed proliferation assumption (PP), the value is 2.5×106/day.
Set constant based on the model yielding timing of peak viremia corresponding to biologically observed timing, and consistent with virion viability ranging from 1∶1 to 1∶1000 [64] and Virion Prod.