title: MALDI-TOF mass spectrometry detection of pathogens in vectors: the Borrelia crocidurae/Ornithodoros sonrai paradigm.
abstract: BACKGROUND
  In Africa, relapsing fever borreliae are neglected vector-borne pathogens that cause mild to deadly septicemia and miscarriage. Screening vectors for the presence of borreliae currently requires technically demanding, time- and resource-consuming molecular methods. Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) has recently emerged as a tool for the rapid identification of vectors and the identification of cultured borreliae. We investigated whether MALDI-TOF-MS could detect relapsing fever borreliae directly in ticks.
  
  
  RESULTS
  As a first step, a Borrelia MALDI-TOF-MS database was created to house the newly determined Mean Spectrum Projections for four Lyme disease group and ten relapsing fever group reference borreliae. MALDI-TOF-MS yielded a unique protein profile for each of the 14 tested Borrelia species, with 100% reproducibility over 12 repeats. In a second proof-of-concept step, the Borrelia database and a custom software program that subtracts the uninfected O. sonrai profile were used to detect Borrelia crocidurae in 20 Ornithodoros sonrai ticks, including eight ticks that tested positive for B. crocidurae by PCR-sequencing. A B. crocidurae-specific pattern consisting of 3405, 5071, 5898, 7041, 8580 and 9757-m/z peaks was found in all B. crocidurae-infected ticks and not found in any of the un-infected ticks. In a final blind validation step, MALDI-TOF-MS exhibited 88.9% sensitivity and 93.75% specificity for the detection of B. crocidurae in 50 O. sonrai ticks, including 18 that tested positive for B. crocidurae by PCR-sequencing. MALDI-TOF-MS took 45 minutes to be completed.
  
  
  CONCLUSIONS
  After the development of an appropriate database, MALDI-TOF-MS can be used to identify tick species and the presence of relapsing fever borreliae in a single assay. This work paves the way for the use of MALDI-TOF-MS for the dual identification of vectors and vectorized pathogens.
authors: URMITE, UMR 6236, CNRS 7278, IRD 198, INSERM 1095, Méditerranée Infection, Faculté de Médecine, Aix-Marseille Université, Marseille, France.
authors: Aurélien
authors: A
authors: Fotso Fotso
authors: URMITE, UMR 6236, CNRS 7278, IRD 198, INSERM 1095, Méditerranée Infection, Faculté de Médecine, Aix-Marseille Université, Marseille, France; URMITE, UMR, IRD 198, Campus IRD Ham Manisty, Dakar, Senegal.
authors: Oleg
authors: O
authors: Mediannikov
authors: URMITE, UMR, IRD 198, Campus IRD Ham Manisty, Dakar, Senegal.
authors: Georges
authors: G
authors: Diatta
authors: URMITE, UMR 6236, CNRS 7278, IRD 198, INSERM 1095, Méditerranée Infection, Faculté de Médecine, Aix-Marseille Université, Marseille, France.
authors: Lionel
authors: L
authors: Almeras
authors: Pôle de Maladies Infectieuses, Assistance Publique-Hôpitaux de Marseille, CHU Timone, Marseille, France.
authors: Christophe
authors: C
authors: Flaudrops
authors: URMITE, UMR 6236, CNRS 7278, IRD 198, INSERM 1095, Méditerranée Infection, Faculté de Médecine, Aix-Marseille Université, Marseille, France.
authors: Philippe
authors: P
authors: Parola
authors: URMITE, UMR 6236, CNRS 7278, IRD 198, INSERM 1095, Méditerranée Infection, Faculté de Médecine, Aix-Marseille Université, Marseille, France.
authors: Michel
authors: M
authors: Drancourt
mesh_terms: D000818:Animals; D001898:Borrelia / Q000737:chemistry* / Q000302:isolation & purification*; D058889:Molecular Typing; D026861:Ornithodoros / Q000382:microbiology*; D012061:Relapsing Fever / Q000382:microbiology / Q000635:transmission; D012680:Sensitivity and Specificity; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*