High efficacy of an in-house antigen B ELISA for diagnosing human cystic echinococcosis compared with a commercial kit and a cell-free DNA assay

Cystic echinococcosis (CE) continues to pose a serious zoonotic health risk in endemic areas. Serodiagnosis, while commonly utilized, faces challenges such as antigenic variability and stage-dependent sensitivity. The purpose of this study was to develop and evaluate an in-house ELISA using the isolated 12-kDa subunit of Antigen B (AgB) from Echinococcus granulosus sensu stricto, as well as to compare its performance to that of a commercial ELISA kit and acell-free DNA (cfDNA)-based PCR test. The 12-kDa AgB component was isolated from sheep hydatid cyst fluid and used to create an in-house IgG ELISA. The diagnostic performance was tested using ROC analysis. A total of 51 surgically and CT-confirmed CE patients and 50 healthy controls were included. Plasma cfDNA was collected and amplified using PCR targeting the COX1 gene. Cohen's kappa and Spearman's correlation were used to determine agreement. The in-house 12-kDa AgB ELISA demonstrated a sensitivity of 90.2%, a specificity of 100%, and an AUC of 0.936. Similarly, the commercial ELISA kit showed a sensitivity of 92.2% and a specificity of 100%. For its part, cfDNA-PCR successfully identified 88.2% of cases and exhibited a specificity of 100%. There was excellent agreement between the in-house and commercial ELISA kits (κ = 0.878) and serological and molecular techniques (κ = 0.78-0.81). The in-house 12-kDa AgB ELISA is a highly reliable and cost-effective diagnostic tool for CE, with performance equivalent to commercial ELISA kits and cfDNA-PCR assays. Future work should prioritize developing standardized recombinant subunits to improve the reliability and accessibility of AgB-based diagnostics in endemic areas. Moreover, direct cyst-tissue DNA warrants evaluation as a more sensitive and stable template for molecular confirmation, potentially overcoming limitations of serological and plasma cfDNA approaches.