Detection of HIV-1 p24 antigen using a simple and highly sensitive chemiluminescence immunoassay

Abstract

Aim: Our study aimed to improve the p24 antigen assay, which is a well-established and widely adopted method for the early detection of HIV-1 infections, in order to increase its sensitivity and efficiency and reduce its cost if possible. Materials & methods: We tested HIV-1 standard p24-positive samples and an HIV-1 p24 antigen panel using a new luminol-based chemiluminescence immunoassay (CLIA) based on a typical ‘sandwich’ p24 ELISA with two antibodies, but utilizing luminol as the luminescence compound, which is oxidized by hydrogen peroxide in the presence of horseradish peroxidase in an alkaline environment. A standard curve for the p24 antigen CLIA was generated and fitted a third-order polynomial regression model very well. To quantify p24 antigen, we investigated the linear standard curve fitting by measuring and comparing the effective assay range, r2 value and error of each function. Results: The p24 antigen CLIA showed a detection limit of 0.5 pg/ml and a detection range of 0.5–5 × 103 pg/ml. The specificity and sensitivity of this assay were further evaluated, and were both found to be 100% for the HIV-1 p24 antigen panel. The luminescence reaction of the CLIA p24 assay takes only 2 min to perform, which greatly reduced the diagnosis time. Additionally, the CLIA p24 assay is as affordable as the normal ELISA method. Conclusion: In our studies, the p24 antigen CLIA shows improved sensitivity, a wider range of response and was less time-consuming than ELISA, as traditional ELISA uses chromogen or a substrate that changes color when cleaved by the enzyme attached to a second antibody. This seems to be an easy and affordable method for the diagnosis of HIV-1 infection and monitoring of disease progression in developing countries. Although more advantages have been seen in CLIA than in ELISA, additional studies are still needed to confirm this.