title: Reliable identification at the species level of Brucella isolates with MALDI-TOF-MS.
abstract: BACKGROUND
  The genus Brucella contains highly infectious species that are classified as biological threat agents. The timely detection and identification of the microorganism involved is essential for an effective response not only to biological warfare attacks but also to natural outbreaks. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) is a rapid method for the analysis of biological samples. The advantages of this method, compared to conventional techniques, are rapidity, cost-effectiveness, accuracy and suitability for the high-throughput identification of bacteria. Discrepancies between taxonomy and genetic relatedness on the species and biovar level complicate the development of detection and identification assays.
  
  
  RESULTS
  In this study, the accurate identification of Brucella species using MALDI-TOF-MS was achieved by constructing a Brucella reference library based on multilocus variable-number tandem repeat analysis (MLVA) data. By comparing MS-spectra from Brucella species against a custom-made MALDI-TOF-MS reference library, MALDI-TOF-MS could be used as a rapid identification method for Brucella species. In this way, 99.3% of the 152 isolates tested were identified at the species level, and B. suis biovar 1 and 2 were identified at the level of their biovar. This result demonstrates that for Brucella, even minimal genomic differences between these serovars translate to specific proteomic differences.
  
  
  CONCLUSIONS
  MALDI-TOF-MS can be developed into a fast and reliable identification method for genetically highly related species when potential taxonomic and genetic inconsistencies are taken into consideration during the generation of the reference library.
authors.affiliation: Histology and Molecular Biology Section, Army Medical and Veterinary Research Center, Via Santo Stefano Rotondo 4, 00184 Rome, Italy.
authors.forename: Florigio
authors.initials: F
authors.lastname: Lista
authors.forename: Frans A G
authors.initials: FA
authors.lastname: Reubsaet
authors.forename: Riccardo
authors.initials: R
authors.lastname: De Santis
authors.forename: Rene R
authors.initials: RR
authors.lastname: Parchen
authors.forename: Ad L
authors.initials: AL
authors.lastname: de Jong
authors.forename: Jasper
authors.initials: J
authors.lastname: Kieboom
authors.forename: Anton L
authors.initials: AL
authors.lastname: van der Laaken
authors.forename: Ingrid A I
authors.initials: IA
authors.lastname: Voskamp-Visser
authors.forename: Silvia
authors.initials: S
authors.lastname: Fillo
authors.forename: Hugo-Jan
authors.initials: HJ
authors.lastname: Jansen
authors.forename: Jan
authors.initials: J
authors.lastname: Van der Plas
authors.forename: Armand
authors.initials: A
authors.lastname: Paauw
mesh_terms: D015373:Bacterial Typing Techniques / Q000379:methods*; D002002:Brucella / Q000145:classification* / Q000302:isolation & purification; D016000:Cluster Analysis; D004269:DNA, Bacterial / Q000235:genetics; D016680:Genome, Bacterial; D018598:Minisatellite Repeats; D020543:Proteome / Q000032:analysis; D013045:Species Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D004269:DNA, Bacterial; D020543:Proteome