Using a Relative Quantitative Proteomic Method to Identify Differentially Abundant Proteins in Brucella melitensis Biovar 3 and Brucella melitensis M5-90

Abstract

Brucellosis, caused by Brucella spp., is one of the most widespread bacterial zoonoses worldwide. Vaccination is still considered the best way to control brucellosis. An investigation into the differential proteome expression patterns of wild and vaccine strains may help researchers and clinicians differentiate between the strains to diagnose and better understand the mechanism(s) underlying differences in virulence. In the present study, a mass spectrometry-based, label-free relative quantitative proteomics approach was used to investigate the proteins expressed by the wild strain, B. melitensis biovar 3 and compare it with those expressed by B. melitensis M5-90. The higher level of virulence for B. melitensis biovar 3 compared to B. melitensis M5-90 was validated in vitro and in vivo. A total of 2133 proteins, encompassing 68% of the theoretical proteome, were identified and quantified by proteomic analysis, resulting in broad coverage of the B. melitensis proteome. A total of 147 proteins were identified as differentially expressed (DE) between these two strains. In addition, 9 proteins and 30 proteins were identified as unique to B. melitensis M5-90 and B. melitensis biovar 3, respectively. Pathway analysis revealed that the majority of the DE proteins were involved in iron uptake, quorum sensing, pyrimidine metabolism, glycine betaine biosynthetic and metabolic processes, thiamine-containing compound metabolism and ABC transporters. The expression of BtpA and VjbR proteins (two well-known virulence factors) in B. melitensis biovar 3 was 8-fold and 2-fold higher than in B. melitensis M5-90. In summary, our results identified many unique proteins that could be selected as candidate markers for differentiating vaccinated animals from animals with wild-type infections. BtpA and VjbR proteins might be responsible for the residual virulence of B. melitensis M5-90, while ABC transporters and thiamine metabolism associated proteins may be newly identified Brucella virulence factors. All of the identified DE proteins provide valuable information for the development of vaccines and the discovery of novel therapeutic targets.

Brucellae as resilient intracellular pathogens: epidemiology, host–pathogen interaction, recent genomics and proteomics approaches, and future perspectives

“…Many studies have suggested several vaccine candidates for DIVA vaccines such as VjbR and BtpA proteins contributed to the virulence of the Y3 and M5 Brucella strains. Zur protein, ABC transporters, and thiamine metabolism-associated proteins may play crucial roles in Brucella survival and pathogenesis ( 148 ). In parallel, Uslu and Erganis revealed that B. melitensis Rev.1 ΔOmp19 can act as a DIVA marker vaccine using an ELISA test for the detection of the Omp19 protein ( 149 ).…”

Gated nanoprobe utilizing metal–organic frameworks for identifying and distinguishing between the wild strains and the vaccine strains of brucella

“…Y3 ( B. melitensis biovar 3) is one of the most common pathogens of brucella, causing 80% of the global epidemic of brucellosis. 15 A19 ( Brucella abortus strains A19) is a vaccine used to prevent brucellosis in about 70% of countries 16 (Scheme 1A). Therefore, we analyzed and compared the complete genome sequences of A19 and Y3, 17 which were obtained from the official website of NCBI.…”