Expression, purification and immunochemical characterization of recombinant OMP28 protein of Brucella species.

Brucellosis is the lion's share of infectious disease of animals and it has a particular socio-economic importance for the Republic of Kazakhstan. Sixty percent of epizootic outbreaks of brucellosis identified in the Commonwealth of Independent States (CIS) originated from Kazakhstan in recent years. Definitive diagnosis of brucellosis remains a difficult task. Precisely for this reason, we evaluated a purified recombinant out membrane protein 28 (rOMP28) of Brucella species (Brucella spp.) produced in Escherichia coli (E. coli) as a diagnostic antigen in an Indirect ELISA (I-ELISA) for bovine brucellosis. The gene encoding OMP28 was synthesized using a two-round PCR procedure. In order to produce the rOMP28, the de novo synthesized DNA was cloned into the expression vector pET-22b(+). Then, the rOMP28 was expressed in E. coli system and characterized in the present study. We further estimated the diagnostic potential of purified rOMP28 of Brucella spp. for screening bovine sera. To determine if rOMP28 has a valuable benefit for use in the serodiagnosis of bovine brucellosis, rOMP28-based I-ELISA was performed. Brucella spp. positive (n=62) and Brucella spp. negative (n=28) samples from tube agglutination test (TAT) were positive (n=59) and negative (n=27) by I-ELISA, respectively. These findings show that the rOMP28 of Brucella spp. could be a good candidate for improving serological diagnostic methods for bovine brucellosis.