title: The relapsing fever spirochete Borrelia miyamotoi is cultivable in a modified Kelly-Pettenkofer medium, and is resistant to human complement.
abstract: BACKGROUND
  Borrelia miyamotoi is a relapsing fever spirochete found in Ixodes ticks in North America, Europe, and Asia, and has recently been found to be invasive in humans. Cultivation of this spirochete has not yet been described, but is important for patient diagnostics and scientific purposes. Host specificity of Borrelia species is dependent on resistance to host complement (serum resistance), and since B. miyamotoi has been identified as a human pathogen we were interested whether B. miyamotoi is resistant to human complement.
  
  
  METHODS
  We inoculated B. miyamotoi strains LB-2001 and HT31 in modified-Kelly-Pettenkofer medium with 10% fetal calf serum (MKP-F), and used standard non-laborious Borrelia culture methods to culture the spirochetes. Next, we assessed serum sensitivity by a direct killing assay and a growth inhibition assay.
  
  
  RESULTS
  We were able to passage B. miyamotoi over 10 times using a standard culture method in MKP-F medium, and found B. miyamotoi to be resistant to human complement. In contrast to B. miyamotoi, Borrelia anserina--a relapsing fever spirochete unrelated to human infection--was serum sensitive.
  
  
  CONCLUSIONS
  Using a variation on MKP medium we were able to culture B. miyamotoi, opening the door to in vitro research into this spirochete. In addition, we describe that B. miyamotoi is resistant to human complement, which might play an important role in pathogenesis. We have also found B. anserina to be sensitive to human complement, which might explain why it is not related to human infection. Summarizing, we describe a novel culture method for B. miyamotoi and show it is resistant to human complement.
authors.forename: Alex
authors.initials: A
authors.lastname: Wagemakers
authors.forename: Anneke
authors.initials: A
authors.lastname: Oei
authors.forename: Michelle M
authors.initials: MM
authors.lastname: Fikrig
authors.forename: Willem R
authors.initials: WR
authors.lastname: Miellet
authors.affiliation: Center for Experimental and Molecular Medicine, Academic Medical Center, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands. lyme@amc.uva.nl.
authors.forename: Joppe W
authors.initials: JW
authors.lastname: Hovius
mesh_terms: D001431:Bacteriological Techniques; D001898:Borrelia / Q000145:classification* / Q000187:drug effects / Q000502:physiology*; D003165:Complement System Proteins / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry*; D006801:Humans; D013997:Time Factors
chemical_list: D003470:Culture Media; D003165:Complement System Proteins