GENOMICS, TRANSCRIPTOMICS, PROTEOMICS Prediction of T cell epitopes of Brucella abortus and evaluation of their protective role in mice Prachiti Afley 1 & Sudhir K. Dohre 1 & G. B. K. S. Prasad 2 & Subodh Kumar 1 Received: 2 May 2015 /Revised: 17 June 2015 /Accepted: 19 June 2015 /Published online: 7 July 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Brucellae are Gram-negative intracellular bacteria that cause an important zoonotic disease called brucellosis. The animal vaccines are available but have disadvantage of causing abortions in a proportion of pregnant animals. The animal vaccines are also pathogenic to humans. Recent trend in vaccine design has shifted to epitope-based vaccines that are safe and specific. In this study, efforts were made to iden- tify MHC-I- and MHC-II-restricted T cell epitopes of Brucella abortus and evaluate their vaccine potential in mice. The pep- tides were designed using online available immunoinformatics tools, and five MHC-I- and one MHC- II-restricted T cell peptides were selected on the basis of their ability to produce interferon gamma (IFN-γ) in in vivo stud- ies. The selected peptides were co-administered with poly DL- lactide-co-glycolide (PLG) microparticles and evaluated for immunogenicity and protection in BALB/c mice. Mice immu- nized with peptides either entrapped in PLG microparticles (EPLG-Pep) or adsorbed on PLG particles (APLG-Pep) showed significantly higher splenocyte proliferation and IFN-γ generation to all selected peptides than the mice immu- nized with corresponding irrelevant peptides formulated PLG microparticles or phosphate-buffered saline (PBS). A signifi- cant protection compared to PBS control was also observed in EPLG-Pep and APLG-Pep groups. A plasmid DNA vaccine construct (pVaxPep) for peptides encoding DNA sequences was generated and injected to mice by in vivo electroporation. Significant protection was observed (1.66 protection units) when compared with PBS and empty vector control group an- imals. Overall, the MHC-I and MHC-II peptides identified in this study are immunogenic and protective in mouse model and support the feasibility of peptide-based vaccine for brucellosis. Keywords Brucella abortus . Epitope . DNA vaccine . Immunoinformatics . PLG microparticles Introduction Brucellae are Gram-negative intracellular bacteria that cause an important zoonotic disease called brucellosis. The genus Brucella includes six classical species namely Brucella melitensis, Brucella abortus, Brucella suis, Brucella canis, Brucella ovis and Brucella neotomae (Corbel 1997). Some more species viz Brucella pinnipedialis, Brucella ceti , Brucella inopinata and Brucella microti were included later on. Brucellosis accounts for more than 500,000 new cases annually. Infection with B. abortus, a species that primarily affects bovines, often results in abortions and infertility in domestic and wild mammals (Franco et al. 2007). The persis- tence of brucellosis in domestic livestock reservoirs remains a continual source of significant numbers of human infections worldwide. Despite regulatory efforts, brucellosis remains en- demic in many parts of the world and is re-emerging in many countries. Vaccination against Brucella infections in animals is usu- ally performed by administration of the live attenuated smooth Brucella strains: B. abortus strain S19 and B. melitensis strain Rev.1. The non-smooth strain B. abortus RB51 was later Electronic supplementary material The online version of this article (doi:10.1007/s00253-015-6787-7) contains supplementary material, which is available to authorized users. * Subodh Kumar subodh@drde.drdo.in 1 Defence Research & Development Establishment, Jhansi Road, Gwalior, Madhya Pradesh 474002, India 2 School of Studies in Biochemistry, Jiwaji University, Gwalior, Madhya Pradesh 474002, India Appl Microbiol Biotechnol (2015) 99:7625–7637 DOI 10.1007/s00253-015-6787-7