Response of Treponema pallidum to certain nutrilites

A review of in vitro attempts to develop the axenic culture of Treponema pallidum and genomics-based suggestions to achieve this elusive goal

To date, the axenic culture of Treponema pallidum remains a challenge in the field of microbiology despite countless attempts. Here, we conducted a comprehensive bibliographic analysis using several databases and search engines, namely Pubmed, Google scholar, Google, Web of Science and Scopus. Numerous unsuccessful empiric studies have been conducted and evaluated using as criteria dark-field microscopic observation of motile spiral shaped cells in the culture and virulence of the culture through rabbit infectivity. All of these studies failed to induce rabbit infectivity, even when deemed positive after microscopic observation leading to the misnomer of avirulent T. pallidum. In fact, this criterion was improperly chosen because not all spiral shaped cells are T. pallidum. However, these studies led to the formulation of culture media particularly favourable to the growth of several species of Treponema, including Oral Microbiology and Immunology, Zürich medium (OMIZ), Oral Treponeme Enrichment Broth (OTEB) and T-Raoult, thus allowing the increase in the number of cultivable strains of Treponema. The predicted metabolic capacities of T. pallidum show limited metabolism, also exhibited by other non-cultured and pathogenic Treponema species, in contrast to cultured Treponema species. The advent of next generation sequencing represents a turning point in this field, as the knowledge inferred from the genome can finally lead to the axenic culture of T. pallidum.

Serum lipoprotein binding by Treponema pallidum: possible role for proteoglycans

Acquisition by the syphilis spirochaete, Treponema pallidum, of radioiodinated total human plasma lipoprotein and lipoprotein subfractions was examined. Time dependent and saturation binding kinetics were observed for total lipoproteins and subfractions, including high density lipoproteins, low density lipoproteins (LDL), and very low density lipoproteins. All subfractions competed equally well in binding iodinated total lipoproteins and individual subfractions, but apoproteins common to all subfractions were ineffective in inhibiting lipoprotein acquisition. The interaction of LDL with T pallidum was studied further and, interestingly, the presence of 17% sulphated dextran sulphate (DS) in the reaction mixture containing treponemes and LDL resulted in up to 172 times more LDL being bound by live treponemes. Biological variability was observed in the extent of increased LDL bound in the presence of 17% sulphated DS by preparations of T pallidum isolated from different infected rabbits. Saturation kinetics of iodinated LDL acquisition was obtained in the presence of 17% sulphated DS but not 1% sulphated DS. Other proteoglycan molecules, such as chondroitin sulphate, hyaluronic acid and heparin, and fibronectin, the extracellular matrix protein targeted by treponemes in parasitism of host cells and tissues neither diminished nor enhanced LDL binding by live treponemes. Only 5% and 10% of associated radioactivity was released from treponemal surfaces after T pallidum was incubated with iodinated LDL and 17% sulphated-DS for 15 and 30 minutes, respectively. These data show binding and possible internalisation of host lipoproteins by T pallidum, which may be mediated by sulphated proteoglycan. Sulphated proteoglycans accumulate during T pallidum infections of host cells.

In vitro cultivation of Treponema pallidum: a review

In vitro cultivation of Treponema pallidum would facilitate many different aspects of syphilis research. This review summarizes developments in this field that have been published since 1975. Findings are discussed in terms of treponemes and the oxygen question, treponemal metabolism involving proteins, nucleic acids, and fatty acids, and treponemal interaction with tissue culture cells. Suggested future approaches and potential problem areas pertinent to successful cultivation are discussed.

Effects of fatty acids on motility retention by Treponema pallidum in vitro

Treponema pallidum (Nichols virulent strain) was incubated under 75% N2 + 20% H2 + 5% CO2 in prereduced serum-free modified Eagle-Richter medium supplemented with different concentrations of various long-chain fatty acids complexed with fatty acid-free bovine serum albumin. Motility retention was greater in medium with oleic acid containing 15 rather than 2 mg of albumin per ml. Palmitic, stearic, oleic, or linoleic acid alone caused rapid loss of motility at concentrations as low as 5 microgram/ml. Elaidic acid (92 microgram/ml) alone had no effect on motility. Various combinations of saturated plus unsaturated fatty acids did not inhibit motility retention or were less inhibitory than either of the individual fatty acid components. The combination of palmitic plus oleic acids was least toxic. Rapid loss of motility occurred with pairs of unsaturated or saturated fatty acids, or with Tween 40, 60, or 80, alone or combined. Autoxidation of oleic acid resulted in decreased toxicity for T. pallidum but increased toxicity for baby hamster kidney cells.

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

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.