In order to study the inuence of different infection modes on HIV infection, an age-structured model incorporating cell-free, cell-to-cell, and cytokine-enhanced viral infection modes is proposed. This model also considers latently infected CD4 + T cells and general incidence rates. The expression of the basic reproduction number R 0 is derived, which includes the contributions from all three infection modes. R 0 serves as the parameter of a threshold dynamics. The threshold dynamics is established by employing the Fluctuation Lemma and the approach of Lyapunov functionals after showing the asymptotic smoothness and uniform persistence of the solution semiflow. Numerical simulations are provided to discuss the effects of the three infection modes on the viral load.