Evaluation of the combined use of the recombinant Brucella abortus Omp10, Omp19 and Omp28 proteins for the clinical diagnosis of bovine brucellosis Hannah Leah Tadeja Simborio a , Jin Ju Lee b , Alisha Wehdnesday Bernardo Reyes a , Huynh Tan Hop a , Lauren Togonon Arayan a , Wongi Min a , Hu Jang Lee a , Han Sang Yoo c , Suk Kim a, d, * a Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 660-701, Republic of Korea b Animal and Plant Quarantine Agency, Anyang, Gyeonggi-do, 430-757, Republic of Korea c Department of Infectious Diseases, College of Veterinary Medicine, Seoul National University, Seoul,151-742, Republic of Korea d Institute of Agriculture and Life Science, Gyeongsang National University, Jinju, 660-701, Republic of Korea article info Article history: Received 20 March 2015 Received in revised form 7 May 2015 Accepted 15 May 2015 Available online 16 May 2015 Keywords: Brucella abortus Recombinant protein Outer membrane protein Serodiagnosis abstract Currently, there are several serodiagnostic tools available for brucellosis, however, it is difficult to differentiate an active infection from vaccination. Hence, there is a great need to develop alternative means that can distinguish between these two conditions without utilizing lipopolysaccharide (LPS). This study was an attempt to determine the efficacy of combined recombinant Brucella (B.) abortus outer membrane proteins (rOmps) and individual rOmps in the serodiagnosis of brucellosis by enzyme linked immunosorbent assay (ELISA), utilizing both that standard tube agglutination test (TAT)-positive and -negative serum samples from Korean native cattle. The results are very interesting and promising because the combined rOmp antigens used in the study were highly reactive with the TAT-positive serum samples. The combined rOmps sensitivity, specificity and accuracy were 215/232 (92.67%), 294/298 (98.66%) and 509/530 (96.04%), respectively. While these results are preliminary, the tests performed have very high potential in the serodiagnosis of brucellosis and likewise, the combined rOmps can be used for future vaccine production. © 2015 Published by Elsevier Ltd. 1. Introduction Brucellosis is a zoonotic disease that occurs worldwide and is caused by bacteria of the genus Brucella, which are Gram-negative, non-spore-forming and nonencapsulated coccobaccilli or short rods with rounded ends [1,2]. Brucellosis is transmitted from do- mestic animals to humans and is endemic in many areas [3]. The organism mainly affects the reproductive system of domesticated animals, causing abortion and infertility, which in turn can cause a serious economic crisis [4]. The definitive diagnosis of brucellosis is isolation and identifi- cation of the causative organism [5]. However, diagnosis and disease control are generally based on serological testing. The Rose Bengal plate test and the complement fixation test are the most acceptable diagnostic methods worldwide [6]; however, Korea utilizes the standard tube agglutination test (TAT) as the main serodiagnostic tool for brucellosis [7]. At present, many developed countries have declared that brucellosis is eradicated and no longer present in their countries [3]. Eradication of the disease can be attained through accurate diagnosis. However, current serological tools available are based on lipopolysaccharide (LPS) components of the organism that cannot distinguish naturally-infected from vaccinated animals with Brucella abortus S19. Therefore, new serological diagnostic tools that not employ LPS are needed. Lindler et al. reported that one non-LPS group of immunogens focused on vaccine and diagnostic purposes is the outer membrane protein (Omp) [8]. The major mechanisms of Omp-mediated bac- terial adaptive responses to the host environment include iron uptake, antimicrobial peptide resistance, serum resistance, multi- drug resistance and bile resistance, among others [9]. However, the Abbreviations: OMP, outer membrane protein; TAT, standard tube agglutination test; ELISA, enzyme linked immunosorbent assay. * Corresponding author. Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju, 660-701, Republic of Korea. E-mail address: kimsuk@gnu.ac.kr (S. Kim). Contents lists available at ScienceDirect Microbial Pathogenesis journal homepage: www.elsevier.com/locate/micpath http://dx.doi.org/10.1016/j.micpath.2015.05.004 0882-4010/© 2015 Published by Elsevier Ltd. Microbial Pathogenesis 83-84 (2015) 41e46