A life cycle for Borrelia spirochetes?
Subsequent to Schaudinn and Hoffman's visualization of Treponema pallidum in 1905, many distinguished syphilologists proposed that spirochetes have a life cycle. What is the "essence" of a life cycle? Simply put, life cycles are diverse arrays of life forms, which emerge in an ordered sequence; which are "connected" to one another across primary and secondary hosts, and constitute a cycle with "circular" relationship between hosts. Fecal-oral life cycles and blood-to-blood life cycles are exemplary of host parasite relationships in this realm. The "blood-to-blood" begins and ends with an insect taking a blood "meal". In this operatic scenario, a "blood-less" insect functions simultaneously as a hypodermic needle and as an incubator for some of the infectious components. The initial phase is inside the body fluid compartment of an insect. The second phase is in the blood or body fluid of a warm-blooded mammal. Third, is the phase inside the cell of a mammalian host. And a final portion of the "life" marked by "death" of the parasitized mammalian cells and the release of infectious parasites which return to the "warm" blood where the "cold blooded" vector again takes a blood meal. The cycle then begins again. In each phase of a blood to blood life cycle, the infectious agent changes its shape. Blood phase "profiles" look different from "tissue phase" profiles. Some of the tissue phase profiles may be "invisible". Borrelia spirochetes offer an excellent example of a life cycle, by virtue of the insect vector to mammalian "piece", the blood and intracellular residence "pieces" and the morphologic diversity "piece". Stereotypes of what a spirochete "should " look like, have actually produced a state of "perseveration" in spirochetal pathobiology. We have been "stuck" like a broken record, on the corkscrew form, and have failed to see the rest of the life cycle. Cystic, granular, and cell wall deficient spirochetal profiles, which were well known in the 19th and 20th centuries by such titans as Schaudinn, Hoffman, Noguchi, Delamater, Steiner, and Mattman, have been repudiated by professional microbiologists, and by pathologists who practice and who confer the status of 21st century truths in microbiology matters. Proper microscopic study, as is required by Dr. Robert Koch's second postulate, for establishing links between microbes and disease, presupposes that the microscopist be aware of the complete array of morphologic repertoires of the alleged pathogen. (Morphologies, which are herein introduced.).
MacDonald
Alan B
AB
St. Catherine of Siena Medical Center, Department of Pathology, 50 Rte 25 A, Smithtown, NY 11787, USA.
D000818:Animals; D001898:Borrelia / Q000254:growth & development* / Q000502:physiology* / Q000648:ultrastructure; D007313:Insecta / Q000382:microbiology*; D008018:Life Cycle Stages; D008954:Models, Biological; D013144:Spirochaetales / Q000502:physiology* / Q000648:ultrastructure