IN VIVO AND IN VITRO OBSERVATIONS OF LEPTOSPIRA POMONA BY ELECTRON MICROSCOPY

Abstract

Miller, Norman G. (University of Nebraska College of Medicine, Omaha) and Richard B. Wilson . In vivo and in vitro observations of Leptospira pomona by electron microscopy. J. Bacteriol. 84: 569–576. 1962.— Leptospira pomona 3341 was observed by electron microscopy, after the preparation of thin sections from culture material and from infected hamster tissue. The external membrane of low electron density envelops the entire leptospire and appears to be quite flexible, as suggested by its many folds. The spiral protoplasmic body is tubular in structure with a relatively dense wall and a central area of low electron density. Occasionally, very dark circumscribed bodies were seen imbedded in the protoplasmic wall. Detailed morphology is presented of a knoblike structure located at the end of the axial filament. Bifurcation of the axial filament could be demonstrated in leptospires from cultures. Leptospires were observed free or enclosed in vesicles within the cytoplasm of liver parenchymal and renal tubule cells. Erythrocytes located in kidney tissue also contained leptospires within the cytoplasm. The appearance of intracellular leptospires is much the same as those seen extracellularly or from culture.

Ultrastructure of Renal Lesions in Pigs with Acute Leptospirosis Caused by Leptospira pomona

“…Results of this study indicate that leptospires enter the kidney hematogenously, migrate through vascular endothelium, persist in the interstitial spaces, and emigrate via the lateral intercellular junctions to reach the tubular lumina. Absence of intact leptospires within tubular epithelial cells agrees with other ultrastructural studies [9,10,19,20,22,23]. Kinetically, the disease may be divided artificially into an "interstitial phase" characterized by edema, vasculitis and leptospiremia, followed by a "tubular phase" during which leptospires are predominantly associated with microvilli of the proximal convoluted tubular lumina.…”

“…Leptospiruria may persist in subclinical, chronic infection and may playa significant role in transmission of the disease to other pigs as well as to cattle [14], man [27], and wild rodents [4,10]. Ultrastructural studies of the kidney in acute leptospirosis largely have been confined to laboratory rodents such as the guinea pig [9], rat (10], mouse (20], and hamster (22,23]. Studies of renal lesions of sheep with experimental leptospirosis show that leptospires in larger mammals are associated with the microvillous border of proximal convoluted tubules [19].…”

In vivo apoptosis of hepatocytes in guinea pigs infected withLeptospira interrogansserovar icterohaemorrhagiae

“…Several histopathological studies of leptospirosis have been reported previously, and these mainly focused on the description of lesions observed in the liver and the kidneys [16–18]. In experimental infection of Syrian hamsters, pathogenic leptospires were observed in the liver, in large number in the intercellular spaces, without systematic alterations of the surrounding hepatocytes [19].…”

In vitro association of leptospires with host cells

“…Other studies have demonstrated leptospires inside cells in various organs from experimentally infected animals (6,8), and Rose et al (10) showed by fluorescent-antibody techniques that leptospires could attain intracellularity in monkey kidney cells. In this study, we showed that pathogenic leptospires can penetrate tight-junctioned epithelial and endothelial cell monolayers in a chemotaxis chamber-filter membrane assembly, while the nonpathogenic leptospires tested could not invade to significant extent.…”