Editing Treponema pallidum (section)

===Culture===
In the past century since its initial discovery, culturing the bacteria in vitro has been difficult.<ref name="Edmondson2018">{{cite journal |vauthors=Edmondson DG, Hu B, Norris SJ |date=June 2018 |title=Long-Term in Vitro Culture of the Syphilis Spirochete ''Treponema pallidum'' subsp. pallidum |journal=mBio |volume=9 |issue=3 |doi=10.1128/mBio.01153-18 |pmc=6020297 |pmid=29946052}}</ref> Without the ability to grow and maintain the bacteria in a laboratory setting, discoveries regarding its metabolism and [[antimicrobial]] sensitivity were greatly impaired.<ref name="Radolf-2018"/> However, successful long-term cultivation of ''T.'' ''pallidum'' in vitro was reported in 2017.<ref name="Edmondson2018" /> This was achieved using Sf1Ep epithelial cells from rabbits, which were a necessary condition for the continued multiplication and survival of the system.<ref name="Edmondson-2021">{{Cite journal |last1=Edmondson |first1=Diane G. |last2=DeLay |first2=Bridget D. |last3=Kowis |first3=Lindsay E. |last4=Norris |first4=Steven J. |date=23 February 2021 |title=Parameters Affecting Continuous In Vitro Culture of ''Treponema pallidum'' Strains |journal=mBio |volume=12 |issue=1 |pages=10.1128/mbio.03536–20 |doi=10.1128/mbio.03536-20 |pmc=8545124 |pmid=33622721}}</ref> The medium TpCM-2 was used, an alteration of more simple media which previously only yielded a few weeks of culture growth.<ref name="Edmondson-2021" /> This success was the result of switching out [[Eagle's minimal essential medium|minimal essential medium]] (MEM) with CMRL 1066, a complex tissue culture medium.<ref name="Edmondson2018" /> With development, new discoveries about ''T.'' ''pallidum''<nowiki/>'s requirements for growth and gene expression may occur and in turn, yield research beneficial for the treatment and prevention of syphilis, outside of a host.<ref name="ReferenceA">{{Cite journal |last1=Edmondson |first1=Diane G. |last2=Norris |first2=Steven J. |date=February 2021 |title=In Vitro Cultivation of the Syphilis Spirochete ''Treponema pallidum'' |journal=Current Protocols |volume=1 |issue=2 |pages=e44 |doi=10.1002/cpz1.44  |pmc=7986111 |pmid=33599121}}</ref> However, continuous efforts to grow ''T. pallidum'' in [[axenic]] culture have been unsuccessful, indicating that it does not satisfy [[Koch's postulates]].<ref>{{Cite journal |last1=Prescott |first1=Joseph |last2=Feldmann |first2=Heinz |last3=Safronetz |first3=David |date=January 2017 |title=Amending Koch's postulates for viral disease: When "growth in pure culture" leads to a loss of virulence |url=|journal=Antiviral Research |volume=137 |pages=1–5 |doi=10.1016/j.antiviral.2016.11.002  |pmc=5182102 |pmid=27832942}}</ref> The challenge likely stems from the organism's strong adaptation to residing in mammalian tissue, resulting in a reduced genome and significant impairments in metabolic and biosynthetic functions.<ref name="Edmondson-2021" />