The kinetics of systemic elevation of TGF-β1 during HIV-1 infection defined in this study parallel those reported in pathogenic non-human primate infection models such as SIVmac infection of rhesus macaques, where a modest increase in circulating TGF-β1 levels is observed from as early as one day post-infection and is maintained throughout acute/subacute and into chronic infection (24), and increased transcription of genes downstream of TGF-β signaling follows similar kinetics (49). Here, TGFB1 is linked to infection.