A previous report by Duquenne et al indicated that an S1PR1 agonist, SEW2871, could induce viral production in an in vitro model of HIV latency in resting PBMCs [14]; however, in our primary cell model of latent HIV infection, we observed only weak LRA activity of FTY720 following 48 hours of culture, likely due to differences in the models used as well as differing mechanisms of FTY720 and other S1PR1 antagonists/ agonists. Here, S1PR1 is linked to HIV infectious disease.