S1PR1 and HIV-1 infection: Of note, blocking egress of migratory T cells from lymph nodes into efferent lymph vessels and interrupting T cell recirculation by the use of a S1PR1 (sphingosine 1-phosphate receptor 1) antagonist FTY720 at early onset of HIV-1 infection resulted in limited HIV-1 dissemination and reduction of plasma viremia (16), indicating that cell-cell transmission of HIV-1 may be important in establishment of systemic HIV-1 infection.