Abstract
Gram-negative bacteria release nanovesicles from their outer membrane, named outer membrane vesicles. The purpose of these vesicles in bacteria physiology is still unknow, and some models have been proposed to explain their production. In last decades, proteomics becomes an important tool to determine the proteins carried in the vesicles. Vesicles contain proteins able to elicit an immune response, so they have been proposed as a model to develop acellular vaccines. Previously, vesicles from Brucella abortus and B. melitensis have been studied and demonstrating to be protective in mice after the challenge with a virulent Brucella strain. In this study, OMVs of Brucella suis, B. ovis, B.canis, and B. neotomae were purified and analyzed by SDS-PAGE, transmission electron microscopy and liquid chromatography coupled to mass spectrometry to determine the pan-proteome. Additionally, antigenic proteins were detected by western blot using rabbit anti-Brucella specific sera. Brucella suis ATCC 23444 (1330), B. ovis ATCC 25840 (63/290), B.canis ATCC 23365 (RM6/66) and B. neotomae ATCC 23459 (5K33) were used in this study. OMVs of B. melitensis, B. ovis, B.canis and B. neotomae showed a spherical shape and bilayer lipid membrane, and sizes between 30-80 nm. The pan-proteome showed many homologous proteins, such as Omp16, Omp25, Omp31, SodC, Omp2a, and BhuA. Proteins contained in the vesicles from different Brucella species were detected by anti-Brucella sera. Also, the proteins found in the Brucella species tested here were also identified within the OMVs of B. suis and B. abortus. The presence of these proteins shared in vesicles of different Brucella species made them candidates to be evaluated as an acellular brucellosis vaccine or in diagnostic tests.
