P6-03 The cloning, expression and immunological evaluation of the Omp31 protein from Brucella melitensis and evaluation of its possible use for diagnosis in bovine brucelosis.

Abstract

This work describes molecular methodologies for the production of OMP31r for the serological diagnosis of bovine brucellosis, which can be caused by biovars of Brucella abortus. Brucellosis is easily transmitted to man and causes an acute febrile illness, undulating fever, which can become chronic and cause serious multisystem complications. Unequivocal diagnosis of Brucella infection can only be made by isolation and identification of Brucella but in situations where bacteriological analysis is not possible, diagnosis can be based on serological methods. Furthermore, false positives can be expected in vaccinated animals, because the antibodies cross-react with infection by the wild-type strain. Serological monitoring tests typically use total antigen such as: Brucella buffered, i.e. rose bengal test (RBT) or buffered plate agglutinationtest (BPAT), or lipopolysaccharides in various ELISA formats. At this point, selecting one or more antigens and using molecular biology to obtain it in its recombinant form would provide a fast and efficient way to innovate in serological diagnostic methods. The Omp31 antigen has been reported for the diagnosis of brucellosis in sheep and goats. In this work, the Omp31 gene from B. melitensis was isolated to be cloned and expressed in a Escherichia coli, where the protein is obtained safely and in large quantities. In this research work, a wide variety of techniques such as bioinformatics, molecular biology, biochemistry and immunology were applied. Omp31r showed a sensitivity and specificity of 77 and 90% and was not recognized by sera from vaccinated animals and by a hyperimmune serum against B. abortus RB51, which is the strain used as a vaccine, which is important since it does not produce false positives, that is to say, it does not produce crossreaction, and the consequent economic cost for the farmer of slaughtering an animal that is not really sick. The Omp31r has optimal performance and quality for use in practical laboratory work and research projects that require the serological diagnosis of Brucellosis sp. This achievement will undoubtedly allow commercial independence in relation to antigen production, taking a big step at the institutional level on the path towards the production of diagnostic kits against Brucella.