Other host genes involved in children B/V prediction include: ADM, ALPL, HK3, MMP9, S100A12, HP, LTF, MPO, MMP8, PGLYRP1, RETN, SERPINA1, S100A9, IFI44l, FAM89A, etc. In this study, we innovatively trained artificial neural network (ANN) and random forest (RF) models using a novel five-gene host signature to diagnose bacterial/viral (B/V) infections in children. The gene discussed is MMP9; the disease is infection.