Obtaining a recombinant antigen for serological diagnostics of brucellosis

Brucellosis of farm animals is one of the most significant problems in the field of practical veterinary science. Timely detection and isolation of infected animals are critically important for preventing the spread of this infection and ensuring the epizootic well-being of the farm. Diagnostic studies for brucellosis are mostly based on serological methods, such as complement fixation reaction and enzyme immunoassay (ELISA). The aim of the study was to obtain a recombinant antigen of brucellosis pathogens and study its serological activity in an indirect solid-phase ELISA. Based on the analysis of immunogenic epitopes of brucellosis pathogen proteins, an antigen was designed, the nucleotide sequence of which was cloned as part of an expression construct based on the pET28a(+) vector. The designed recombinant brucellosis antigen was successfully synthesized in cultures of the producer bacterial strain and purified using affinity chromatography. The resulting preparation was used in a dilution of 10 micrograms/ml as an antigen in an indirect solid-phase ELISA to detect antibodies against brucellosis. According to the ELISA results, it was found that the recombinant antigen exhibited serological activity against anticellular A-, S-, and M-antibodies. The specificity coefficient was calculated relative to the ELISA data with blood serum in a dilution of 1:128. Thus, for the recombinant antigen in the reaction with cattle blood serum against Brucella abortus, the specificity coefficient was 3.5, B. melitensis - 5.5, Brucella S antigen - 14.25, R antigen - 0.75. Thus, the developed antigen showed great potential for use in serological reactions for the indication of antibodies against brucellosis pathogens, which are characterized by growth in the S-form of bacterial colonies.