CD4 and HIV-1 infection: If this hypothesis were to be confirmed by future studies, the 2-LTR concentration in peripheral blood could serve as an important biomarker for HIV-1 infection and treatments in addition to the plasma viral load and CD4 count since 2-LTR has already been used to indicate the actively viral replication or the potency of antiretroviral drug such as the integrase inhibitor raltegravir [44], [46].