CD4 and HIV infectious disease: The susceptibility of CD4+ T cells to HIV infection has also been linked with mTOR signaling, as inhibition of mTOR with rapamycin decreases expression of the HIV coreceptor CCR5 on T cells (29, 30), and mTOR has also been implicated in regulating HIV latency, with inhibition of mTOR shown to suppress HIV reactivation (31, 32).