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

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.

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.

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.

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.