Using dot-immunoassay in decoding the outbreak of pseudotuberculosis in the Tomsk region

Abstract

Background. Pseudotuberculosis remains a serious healthcare problem, which determines the expediency of developing the express methods for its early diagnosis. To detect the pathogen, we designed test system for dot-immunoassay (DIA) based on antibodies labeled with silver nanoparticles (SNPs) isolated from hyperimmune rabbit serum obtained against killed cells of Yersinia pseudotuberculosis of O:1b serovariant.The aim. To assess the possibility of using dot-immunoassay for express identification of Y. pseudotuberculosis cultures isolated from clinical material and environmental objects at the initial stage of bacteriological study during laboratory diagnosis of the disease.Methods. We used the materials from the outbreak of pseudotuberculosis in the Krylovskaya Boarding School of the Bakcharsky district of the Tomsk region in 2021. Specific antibodies from hyperimmune rabbit sera obtained against Y. pseudotuberculosis 3704 particulate antigen of O:1b serotype were labeled with SNPs and used in DIA on nitrocellulose membranes with visualization of reaction results with a solution of a physical developer. The presence of the causative agent of pseudotuberculosis in the test material was inferred by the formation of gray spots of different intensity (from 4+ to 1+).Results. All Y. pseudotuberculosis strains isolated using bacteriological method on the second day of the study from clinical material obtained from sick people and environmental objects were detected in DIA at concentrations ≥ 3.1 × 104 microbial cells per milliliter (m.c./ml).Conclusion. The designed test system for dot-immunoassay using SNPs as a marker of specific antibodies for the detection of Y. pseudotuberculosis in cultures isolated from swabs from vegetables and clinical material from patients, including those with mixed infection, allows us to detect a specific corpuscular antigen with a high sensitivity (≥ 3.1 × 104 m.c./ml), providing express identification of isolated cultures at the initial stage of bacteriological study.