Studies on the Life Cycle of Spirochetes

Abstract

In papers published elsewhere (1-5) descriptions of the life cycles of two strains of non-pathogenic Treponema pallidum are given as they occur in culture and in the embryonated egg. In these studies the sequence of events was apparent from the study of cultures of successive ages, and in many instances sequences from one cell form to another in such processes as transverse division followed in single organisms. While recognizing the inherent danger of drawing analogies between different organisms and their basic biological processes, it still seemed justifiable to attempt to establish whether or not a sequence of events comparable to that observed in the saprophytic strains might not also occur in the pathogenic Treponema pallidum as it occurs in the syphilitic rabbit testis. In addition to the studies by the present authors, previous studies briefly summarized in one of the papers above mentioned further suggested the possibility that a complex life cycle also occurred in this organism. The purpose of the present paper is to present a series of observations made by means of phase contrast microscopy on preparations made from syphilitic rabbit testes. Interpretations of the structures observed are based, at least in part, upon the analogies which can be drawn between these organisms and the saprophytic forms, and also upon successive observations of the same preparations over periods of hours and even days. In these preparations definite changes in the organisms were observed to occur, and it now seems likely on the basis of work done since these initial observations were made, that these changes truly represent the proper sequence of events as they occur in the living testis as well as in cultures of the pathogenic spirochete.

Morphology and dynamics of protruding spirochete periplasmic flagella

“…Spirochetal protrusions have been noted previously by dark-field, phase-contrast, and electron microscopy (19,25,26,31,35,(37)(38)(39)44). These protrusions were reported as being flagella (26,(37)(38)(39) or simply extensions of the helical cell cylinder (36,45).…”

“…These protrusions were reported as being flagella (26,(37)(38)(39) or simply extensions of the helical cell cylinder (36,45). Cells with protrusions were commonly noted in old cultures (25) and were believed to be part of a spirochetal life cycle, proceeding from a helical cell cylinder to a final spherical cystlike form (19,25,26). Most of these studies were done before the unique ultrastructure of spirochetes was understood, e.g., before it was known that these organisms are surrounded by an outer membrane sheath (27).…”

“…In the process of characterizing T. phagedenis cells and PFs, we observed helical protrusions gyrating on a small fraction of motile T. phagedenis cells. Sporadic reports of protrusions have appeared in the literature, going back several decades (19,25,26,31,35,(37)(38)(39)44), but their morphology and dynamics have not been analyzed in detail.…”

A new class of protein sensor links spirochete pleomorphism, persistence, and chemotaxis

“…Spirochetes are typically present as long, thin spiral-shaped cells that are motile and chemotactic, but can form round bodies and biofilms. Round bodies have been investigated in the spirochetes Td 37 , Bb 4,5,38 and Treponema pallidum ( Tp ) 39 through microscopy methods and has led to an established model for their formation (Fig. S1) 10 .…”

Spirochete from the Rabbit Tick,Haemaphysalis leporispalustris(Packard) I. Isolation and Preliminary Characterization

“…One considers transverse division or binary fission as the only means of reproduction, whereas the other postulates an additional, rather complex developmental cycle consisting of the production of "granules" from which, by elongation, new spirochetes may develop. The voluminous literature regarding this controversial issue has been reviewed by several authors for the louseand tick-borne relapsing fever agents (5,8), as well as for other spirochetal organisms (3,11). The present consensus is that spirochetes in general do not have a complex life cycle but multiply by binary fission only.…”