A Recombinant RABV-G-Based Chemiluminescence Immunoassay for Quantitative Detection of Rabies Virus Antibodies

Background: Rabies is a nearly 100% fatal zoonosis, and a rabies virus-neutralizing antibody (RVNA) titre of ≥0.5 IU/mL is the recognized correlate of protection, making post-vaccination serological monitoring essential. However, the gold-standard methods (RFFIT and FAVN) are time-consuming, require live virus, and are unsuitable for large-scale surveillance, while current ELISA kits often show poor concordance with neutralization tests. Methods: In this study, we established a chemiluminescence immunoassay (CLIA) employing magnetic beads coated with recombinant RABV glycoprotein (short-chain) and an acridinium ester-labeled rabbit anti-dog IgG. Results: The assay exhibited a detection limit of 0.24 IU/mL. Its performance was validated with 250 canine anti-RABV serum samples against the FAVN. The CLIA and FAVN results were strongly correlated (r = 0.9636, p < 0.0001), with a Deming slope of 0.96 (95% confidence interval: 0.92–1.00). The assay achieved a diagnostic sensitivity of 94.4% and a specificity of 97.1%. It demonstrated high accuracy (relative bias within ±10%), good repeatability (intra- and inter-assay coefficients of variation < 8%), and acceptable specificity, showing no cross-reactivity with canine parvovirus, canine distemper virus, or canine parainfluenza virus antibodies. Conclusions: This CLIA kit eliminates the need for live virus, yields quantitative results within 30 min, and offers simple operation and high-throughput capacity, making it a reliable and practical tool for rabies immune monitoring and scientific prevention and control.