Application of Outer Membrane Protein Omp25 in Serological Diagnosis of Brucellosis

Background: Brucellosis remains a widespread zoonotic disease where serodiagnosis is critical for control. Outer membrane protein 25 (Omp25) has emerged as a promising diagnostic antigen, yet the optimal antigen format for Omp25-based serological assays remains unclear. Methods: We performed a systematic review and meta-analysis of diagnostic accuracy studies following PRISMA-DTA 2020 guidelines. Four electronic databases were searched through July 16, 2026. Risk of bias was assessed using QUADAS-2. Diagnostic accuracy was synthesized using the bivariate binomial model, with subgroup analyses stratified by host species and antigen format. Results: Ten diagnostic accuracy studies comprising 23 study arms were included. Substantial heterogeneity was observed (I2 = 86.2% for sensitivity, 68.4% for specificity). In human serum, pooled sensitivity was 0.93 (95% CI: 0.89–0.96) and specificity was 0.97 (95% CI: 0.93–0.99). In ruminant serum, pooled sensitivity was 0.89 (95% CI: 0.81–0.94) and specificity was 0.95 (95% CI: 0.91–0.97). Multi-protein formats demonstrated narrower confidence intervals and more consistent diagnostic reliability than monomeric Omp25, despite a marginally lower pooled sensitivity point estimate. Single Omp25 exhibited the widest cross-species performance variation. Reference standard heterogeneity affected apparent specificity, with RBT + SAT dual standards yielding higher specificity than single RBT. Conclusions: Multi-protein antigen formats offer more consistent diagnostic reliability than monomeric Omp25 for brucellosis serodiagnosis, though performance varies significantly by host species. Clinical translation requires standardized antigen preparation protocols, uniform reference standards, and cautious species-specific application. Future research should prioritize larger, species-stratified, multi-center validation and prospective trials to establish Omp25-based DIVA capability.