To boost or not to boost: Immune activation in HIV infection

Various clinical experiments have suggested the significant role of CD4+ T cells activation in viral spread and immune control of HIV infection. In this paper, we use a new mathematical model to explore the intricate interactions among immune activation, CTL response, T cell depletion, and immune escape. It is shown that enhanced immune activation and proliferation of CD4+ T cells, opposite to its beneficial effects in other infections, may facilitate infection and lead to the depletion of CD4+ T cells if effective immune control is not established. By contrast, once effective CTL response to HIV is mounted, the boost of CD4+ T cell response may be beneficial for controlling infection and alleviating immune impairment. Another finding is that immune escape may occur when the infection rate is low, and enhanced activation may prevent the escape if effective immune control can be established. Simulations are provided to illustrate the theoretical analysis.