However, the rate of false positives (FP) by the fourth‐generation assay was high in situations of low HIV prevalence.12, 13, 14 The present study was carried out to analyze the influence of s/co ratios by Architect HIV Ag/Ab Combo with the results of supplemental tests and explore the optimal cutoff value to predict HIV infection. The gene discussed is RENBP; the disease is HIV infectious disease.