Breakthrough In Vitro Model of Syphilis Spirochete

Treponema pallidum is a pathogenic, obligate spirochete and causative agent of the sexually transmitted disease syphilis. Historically considered an unculturable organism in vitro, isolation and propagation of T. pallidum has been limited to rabbits and other animal models of infection.¹ The lack of in vitro methods of culture has stymied research into this critical disease.

Recently, the lab of Dr. Steven Norris has made a tremendous breakthrough by finally achieving stable growth of this important pathogen in vitro. The Nichols strain was originally isolated in 1912 from the cerebrospinal fluid of a human patient with recurrent neurosyphilis. By 1982, the strain Nichols (Houston) was established as a laboratory clone of the original Nichols strain that had been continually passaged since its isolation.

The recent optimization of an in vitro method in Sylvilagus floridanus (cottontail rabbit) epithelial cells (Sf1Ep; ATCC® CCL-68™) with a specialized growth medium has allowed for continuous propagation while maintaining the characteristic ultrastructure and full infectivity in vivo.¹

BEI Resources is proud to be among the first in the world to offer an in vitro-propagated strain of T. pallidum to the scientific community. Available as NR-59701, Treponema pallidum subsp. pallidum, Strain Nichols (Houston) is suitable for propagation both in vitro and in vivo.

References:

1. . Edmondson, D. G., et al. “Clonal Isolates of Treponema pallidum subsp. pallidum Nichols Provide Evidence for the Occurrence of Microevolution During Experimental Rabbit Infection and In Vitro Culture.” PLoS One 18 (2023): e0281187. PubMed: 36917571.