Untreated animals were sacrificed during acute [SIV+ Acute; n = 4; sacrificed 4 weeks post infection (WPI); median plasma viral load: 1,395,000 SIV RNA copies/mL] or chronic infection [SIV+ Chronic; n = 12; sacrificed a median of 53.5 WPI; median plasma viral load: 200,904 SIV RNA copies/mL; median CD4+ T cells: 382.5 cells/mm3]. The gene discussed is CD4; the disease is infection.