Retention of motility and virulence of Treponema pallidum (Nichols strain) in vitro

Abstract

A maintenance medium for Treponema pallidum was designed to hold its Eh at the optimum for that organism, -10 to -110 mV. After 100% motile (freshly harvested) T. pallidum was inoculated into the medium, the motility of the treponemes decreased to 80% after 2 days, 50% after 3.5 days, and 0% after 9 days during incubation at 34 C. Full virulence was retained for 2 days, but it dropped rapidly thereafter, and the treponemes became avirulent by day 5.

Virulent Treponema pallidum: aerobe or anaerobe

“…Essential nutritional and metabolic data required for the successful cultivation of virulent Treponema pallidum, the causative agent of syphilis, are lacking. Since these microorganisms have not been grown in vitro, the majority of literature represents attempts to develop experimental methods that prolong the motility and virulence of T. pallidum in artificial media (10,22,23). These studies have been performed under anaerobic or chemically reduced conditions because members of the genus Treponema are classified as strict anaerobes (7), and reports indicate that anaerobiosis or strong electronegative redox potentials extend survival time of T. pallidum in vitro (10,16,18,22,23).…”

“…Radioisotopes and chemicals. The following radioisotopes were supplied by ICN Radioisotope Division: L-[U-14C]pyruvate, 129 mCi/mmol; L- [U-14C]glucose, 180 mCi/mmol; I1-'4C]glucose, 10 mCi/ mmol; and t6-'4C]glucose, 10 mCi/mmol. [1-14C]pyruvate, 7.2 mCi/mmol, was purchased from 704 on August 11, 2020 by guest http://iai.asm.org/ Downloaded from VIRULENT T. PALLIDUM: AEROBE OR ANAEROBE New England Nuclear Corp., and a purified 3Hlabeled amino acid mixture was purchased from Schwarz-Mann.…”

Unsustained multiplication of treponema pallidum (nichols virulent strain) in vitro in the presence of oxygen

“…This strongly suggests that the treponemes are epicellular rather than intracellular. It has been established by earlier investigators and reconfirmed in our laboratory that an increasing MDIA suggests a progressive loss in numbers of virulent microorganisms (13,17,24,27,28). The results of the tests shown in Tables 4 and 5 suggest that numbers of virulent microorganisms decrease regardless of the presence or absence of increases in the number of treponemes during incubation.…”

“…Samples for virulence testing, 0.8 ml each, were withdrawn from the supematant fluids of cell-free and cell co-incubation cultures and diluted into 0.2 ml of 50% glycerol + 50% medium in 1-dram vials. The samples were stored at -77°C until used for intradermal inoculation (0.1 ml/site) into the shaved backs of 3.5to 4-kg male Dutch Belt rabbits (13). The cell monolayers with attached treponemes were rinsed with a calcium-and magnesium-free salt solution (20) and removed from the Leighton tubes by using 0.5 ml of a solution containing 0.05% trypsin (Difco, 1:250) and 0.05% ethylenediaminetetraacetate (Difco).…”

Rate of clearance of virulent Treponema pallidum (Nichols) from the blood stream of normal, Mycobacterium bovis BCG-treated, and immune syphilitic rabbits

“…T. pallidum will readily attach to host cells, but whereas antibody has been reported to enhance the attachment (12,14,16) intravenously ranged from 5.2 x 107 to 2.8 x 10, (mean, 1.3 x 108). T. pallidum were obtained from the testes of orchitic syphilitic rabbits by mincing tissue in an anaerobic maintenance medium (9).…”