The interaction of Treponema pallidum (Nichols strain) with 19 different cultured mammalian cell types was examined. These types included cells derived from testis, kidney, spleen, lung, epidermis, cervix, urethra, and nerve tissue of human, rabbit, or rat origins. They represented normal and malignant cells, epithelial and fibroblastic morphology, cell lines, and cell strains, Large numbers of organisms attached to the cultured cells; this attachment prolonged the time of retention of active treponemal motility. Attachment was examined in terms of the number of treponemes inoculated, cultured cells present, and actively growing versus stationary cultured cells; the motility of the treponemes; the viability of the cultured cells; and the different cell passages. In sharp contrast to the attachment of T. pallidum, 11 nonpathogenic treponemes failed to attach to cultured cells. Immune syphilitic rabbit serum prevented the attachment of T. pallidum to cultured cells, as indicated by phase contrast microscopy and rabbit inoculations. This blockage of attachment by immune serum occurred without interfering with active motility of the organisms. Results are discussed in terms of the potential relationship of attachment to the pathogenicity of T pallidum.
Electron microscope studies of ultrathin sections of material from human syphilitic lesions have been relatively few in number and appear to have been initiated by Drusin, Rouiller, and Chapman (1969) who studied biopsy material from a 2-week-old penile lesion occurring on the glans penis of a 22-year-old male. Hasegawa (1969) reported studies on papular
SUMMARYThe influence of Mg2+-lirnitationy compared with carbon-limitation, on bacterial concentration, and on protein, carbohydrate, RNA and DNA contents of Aerobacter aerogenes cultures (grown in the chemostat at several dilution rates) was determined. In both types of culture the bacterial protein, carbohydrate and DNA contents varied slightly, and the RNA content grossly, with changes in dilution rate. Bacterial yield varied with growth rate, and to a marked degree in the Mg2+-limited culture; this resulted from Mg2+ control of RNA synthesis. A growth-rate independent stoichiometry between RNA and Mg2+ was observed; 4 moles of RNA nucleotide were synthesized per mole of Mg2+ present in the culture. The protein and RNA distributions between cellular components varied with growth rate. The ribosomal fractions increased with increasing growth rate, as did the RNA:protein ratios in these fractions, in both cultures. Mg2+-limited bacteria contained little polysaccharide ; washed suspensions of such organisms synthesized polysaccharide from glycerol at a low rate as compared with C-limited bacteria. Added Mg2+ stimulated polysaccharide synthesis by Mg2+-limited bacteria but not by C-limited bacteria. Washed suspensions of bacteria were induced to synthesize B-galactosidase. With cultures grown at three different dilution rates, the rates of enzyme synthesis in C-limited bacteria were twice those found with Mg2+-limited bacteria, though both had equal ribosome contents.
Cultured mammalian cells extend the time of survival of Treponema pallidum (Nichols strain). Various parameters that have been previously shown to enhance treponemal survival in vitro were examined for influences on the interaction of T. pallidum with cultured cells. With cells derived from normal rabbit testes, the time of retention of treponemal virulence was extended in an atmosphere containing reduced concentrations of oxygen. Glutathione and cysteine, when added to the basal tissue culture medium, prolonged treponemal survival. In an assessment of various tissue culture medium supplements, normal rabbit serum was equivalent to fetal bovine serum and superior to bovine serum albumin fraction V (BSA), fatty acid-poor BSA, and lipid-poor BSA. Beneficial effects on the retention of treponemal virulence were also observed for TRK-2, HSE, NRK, and C6 cells. Dithiothreitol, as an additional reducing agent, sharply enhanced treponemal survival. With SF1Ep NBL-11 cells and basal tissue culture medium containing gluthathione, cysteine, and dithiothreitol, in an atmosphere of approximately 3% oxygen, T. pallidum was maintained without detectable decreases in the number of virulent organisms for 6 days.
This paper describes the attachment of Treponema pallidum (Nichols strain) to cultured mammalian cells as a visualized by scanning electron microscopy. Treponemes were incubated for 3 hr with cultured cells derived from normal rabbit testes or human skin epithelium, then fixed, processed with critical-point drying, and examined with a Cambridge Mark 2A scanning electron microscope. Large numbers of treponemes became attached to the cultured cells without altering the morphological integrity of the cultured cells. Attachment appeared to involve a very close physical proximity of treponemes to the cultured cells; at the site of attachment, no changes such as swelling or indentation of the cultured cell surface were observed. The addition of ruthenium red to the fixatives produced a treponemal-associated surface precipitate. This material, which is probably mucopolysaccharide and/or phospholipid, may be important in protecting the organisms against host defense mechanisms; in addition, it may be involved in the serological unresponsiveness of freshly prepared suspensions of T. pallidum.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.