Metabolic Activity of Purified Suspensions of Rickettsia rickettsi

Weiss, Emilio; Rees, Horace B.; Hayes, Jude R.

doi:10.1038/2131020a0

Cited by 37 publications

(29 citation statements)

References 16 publications

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“…The typhus and spotted fever rickettsiae appear to utilize glutamate somewhat more rapidly than glutamine (23,24,30). It was shown by Hahn et al (9) that glutamine is deaminated to glutamate, but otherwise the pathway appears to be the same.…”

Section: Resultsmentioning

confidence: 93%

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Substrate utilization by Ehrlichia sennetsu and Ehrlichia risticii separated from host constituents by renografin gradient centrifugation

et al. 1988

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The in vitro metabolic activities of two monocytic species of Ehrlichia were investigated. The Miyayama strain of Ehrlichia sennetsu and two strains of Ehrlichia risticii, isolated in Illinois and Maryland, were cultivated in a P388D1 mouse macrophage cell line. The ehrlichia particles from heavily infected cultures were separated from host constituents by a Renografin gradient centrifugation procedure modified from those employed for rickettsiae and chlamydiae. The metabolic activities of the isolated ehrlichiae were measured by their formation of CO2 after incubation for 1 h or longer at 34°C with 14C-labeled substrates. Of the substrates tested, glutamine was utilized most vigorously. The greatest activity was obtained at pH 7.2 to 8.0, while the activity rapidly declined at pH below 7. The most favorable buffer was one that contained 0.05 M potassium phosphate as well as 0.2 M sucrose, thus affording some osmotic protection. Glutamate was utilized to a much lesser extent than glutamine, and glucose was not utilized at all. No consistent differences in metabolic activities among the three strains were observed.During the past several years there has been a resurgence of veterinary, medical, and biological interest in the genus Ehrlichia, previously believed to include only veterinary pathogens. In 1981 Ristic et al. (21) observed that there was a serological relationship between Rickettsia sennetsu and Ehrlichia canis. This was quickly followed by a report by Hoilien et al. (10), who illustrated the pronounced similarity in the developmental cycles of the two agents. This led to the reclassification of R. sennetsu as Ehrlichia sennetsu by Ristic and Huxsoll (20). E. sennetsu is a human pathogen isolated in 1953 in Japan (15), and until recently it was believed to be confined to a small region of that country (19). E. canis has been recognized for over 50 years as a worldwide pathogen of dogs (20).Cole et al. (3) greatly facilitated the investigation of E. sennetsu by demonstrating that this agent can be cultivated readily in an established cell line, P388D1, derived from murine macrophages. When Potomac horse fever, a disease that made its first appearance in Maryland about a decade ago, was investigated, it became obvious that the etiologic agent was an ehrlichia related to E. canis but more closely related to E. sennetsu (11). The agent was named Ehrlichia risticii (12), and the disease was renamed equine monocytic ehrlichiosis. These findings raise many questions about the ecology and phylogeny of E. sennetsu and E. risticii, which are widely separated geographically and are pathogenic for different mammalian hosts. The possibility that E. canis is the common link and that the dog is the common reservoir was raised by the discovery that E. canis can infect humans and produce a disease that is somewhat similar to Rocky Mountain spotted fever (7,14).Information on the biological properties of Ehrlichia spp. is quite limited. No detailed studies of the metabolic properties of any of the ehrlichiae have been r...

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Section: Resultsmentioning

confidence: 93%

“…The two Ehrlichia species resemble rickettsiae in their apparent lack of a glycolytic pathway and in their activity in the presence of glutamine (23,24,30). The typhus and spotted fever rickettsiae appear to utilize glutamate somewhat more rapidly than glutamine (23,24,30).…”

Section: Resultsmentioning

confidence: 99%

Substrate utilization by Ehrlichia sennetsu and Ehrlichia risticii separated from host constituents by renografin gradient centrifugation

et al. 1988

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“…11 Supernatants containing rickettsiae were centrifuged at 10,400 × g for 30 min. 12 Rickettsial pellet was suspended in K36 buffer, 13 and then layered on 20-45% linear Renografin gradient for centrifugation at 141,000 × g for 90 min with rotor SW28 (Beckman, Fullerton, CA ). 12 The light band of the rickettsial layers was collected and subjected to a second round of Renografin gradient centrifugation.…”

Section: Methodsmentioning

confidence: 99%

Exploratory Study on Pathogenesis of Far-Eastern Spotted Fever

Duan

Meng²,

Wang³

et al. 2011

The American Society of Tropical Medicine and Hygiene

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Far-eastern spotted fever is an emerging disease caused by Rickettsia heilongjiangensis, a tick-borne obligate intracellular bacterium. In this study, R. heilongjiangensis was used to infect BALB/c mice by inoculation of retro-orbital venous plexus to imitate a blood infection caused by tick biting. We found that R. heilongjiangensis rapidly entered the circulation for systemic dissemination and the pathogen existed in liver, spleen, lungs, and brain of the mice at least 9 days post-infection (p.i.). Severe pathological lesions were observed in liver, lungs, and brain at Day 6 p.i. In addition, the elevated levels of inflammatory cytokines, including interferon-γ, tumor necrosis factor, and CC chemokine, were detected in the infected organs at Day 3 p.i. Our results reveal that R. heilongjiangensis may cause an infection in BALB/c mice and the pathological lesions in the infected mice are associated with host inflammatory response induced by R. heilongjiangensis.

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“…These compounds were diluted with their unlabeled counterparts to provide 2 (1.mo1 and 0.05 pCi per vessel. Formation of CO: was determined as described previously (42,43) but modified recently (40) in tubes (16 by 100 mm) containing final volumes of 0.4 ml. These tubes were closed with rubber stoppers from which plastic caps containing filter paper wicks were suspended.…”

Section: Methodsmentioning

confidence: 99%

Differential Characteristics of Strains of Rochalimaea: Rochalimaea vinsonii sp. nov., the Canadian Vole Agent

Weiss

Dasch

1982

International Journal of Systematic Bacteriology

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A series of comparative studies was carried out on the Fuller and Guadalupe strains of Rochalimaea quintana and the vole agent described by Baker in 1946. No differences were encountered between the two strains of R . quintana. The vole agent resembled R . quintana in most of its phenotypic characteristics, but, in contrast to R . quintana, did not require C02 for growth, catabolized glutamate without an added energy-yielding substrate, and autoagglutinated. Comparisons of the migration patterns of various protein fractions in gels by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, line-rocket immunoelectrophoresis, and enzyme-specific staining confirmed the identity of the two strains of R . quintana and their similarity to the vole agent. Although many of the proteins had the same function as enzymes in R . quintana and the vole agent or reacted equally well with both homologous and heterologous sera, they migrated at different rates in the gels. Therefore, on the basis of this and previously reported evidence, we propose that the vole agent be named Rochalimaea vinsonii sp. nov. This name honors J. William Vinson, who, in collaboration with Henry S. Fuller, established that R . quintana can be grown axenically and initiated studies of the genus Rochalimaea by conventional bacteriological techniques. The type strain of R . vinsonii is ATCC VR-152.

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Metabolic Activity of Purified Suspensions of Rickettsia rickettsi

Cited by 37 publications

References 16 publications

Substrate utilization by Ehrlichia sennetsu and Ehrlichia risticii separated from host constituents by renografin gradient centrifugation

Substrate utilization by Ehrlichia sennetsu and Ehrlichia risticii separated from host constituents by renografin gradient centrifugation

Exploratory Study on Pathogenesis of Far-Eastern Spotted Fever

Differential Characteristics of Strains of Rochalimaea: Rochalimaea vinsonii sp. nov., the Canadian Vole Agent

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