This timepoint from the post-acute phase of SIV infection was selected as it corresponds with the establishment of viral setpoint (median SIV viremia 5.41 (1.63-6.18) log10 copies/mL of plasma) and there is evidence of immunosuppression including lowered, yet stable peripheral CD4 counts (median 399 (333–901) cells/μL of blood) and decreased frequencies of CD4 T-cells in the gut mucosa relative to SIV-naïve controls (Supplementary Figure 2, Supplementary Table 1). Here, CD4 is linked to heterotaxy, visceral, 5, autosomal.