Figure 2.

Dissociation of HIV-1 from FDC during HAART. The number of bound virions per CR2 on FDC, Σ_i=1ⁿ B_i/R_T, is plotted as a function of time t. Treatment begins at t = 0. For t > 0, we assume there is no attachment of HIV-1 to FDC. The time course of dissociation during (a) the first 2 d of treatment or (b) the first 200 d of treatment is determined from Eqs. 1 and 2 with n = 20, K_xR_T = 1.1427 and k_r = k_−x = 0.1 s⁻¹. After the value of n is specified, the value of K_xR_T is chosen so that the level of virus on FDC after 180 d of treatment is 10,000-fold less than that after 2 d of treatment. The dotted line in a is based on the initial condition B₁ = R_T (each receptor is initially bound to a single virion). The solid line is based on a more realistic initial condition, which is determined from the steady-state form of Eqs. 1 and 2 with the associative rate αVR (αV = 3.5576 × 10⁻⁶ s⁻¹) added to the expression for dB₁/dt in Eq. 1. With this initial condition, Σ_i=1ⁿ B_i/R_T = 0.05, and virions are distributed in various bound states at t = 0.