Syphilis research has been severely limited by the necessity to propagate Treponema pallidum in vivo in rabbits. After decades of erroneous or irreproducible reports of cultivation of T. pallidum , the recent very convincing report of its successful long-term in vitro propagation opens numerous opportunities for development of genetic tools for studying pathogenesis and protein function, antigenic variation, and surface exposure of antigens. The possibility of more rapid isolation of new strains will expand our knowledge of this organism beyond the century-old Nichols strain.
Lukehart, S. A. (2018). New Tools for Syphilis Research. MBio, 9(4). https://doi.org/10.1128/mbio.01417-18