HPRT1 and dengue disease: In order to determine if the combination suggested by the programs was accurate, the relative fold expression of the reference genes against IL-6, an anti-inflammatory cytokine produced during dengue was studied by normalizing to the geometric mean of the reference genes in two groups (i) most stable genes (ACTB, HPRT, GAPDH) and (ii) least stable genes (COX, B2M, HMBS).