scholarly journals Characterization of Mutations in therpoB Gene in Naturally Rifampin-ResistantRickettsia Species

1999 ◽  
Vol 43 (10) ◽  
pp. 2400-2403 ◽  
Author(s):  
Michel Drancourt ◽  
Didier Raoult
Keyword(s):  
Spotted Fever ◽  
Single Point ◽  
Experimental Studies ◽  
Single Point Mutation ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Resistant Species ◽  
Encoding Gene ◽  
Group Species

ABSTRACT Rickettsiae are gram-negative, obligately intracellular bacteria responsible for arthropod-borne spotted fevers and typhus. Experimental studies have delineated a cluster of naturally rifampin-resistant spotted fever group species. We sequenced the 4,122- to 4,125-bp RNA polymerase β-subunit-encoding gene (rpoB) from typhus and spotted fever group representatives and obtained partial sequences for all naturally rifampin-resistant species. A single point mutation resulting in a phenylalanine-to-leucine change at position 973 of theRickettsia conorii rpoB sequence and present in all the rifampin-resistant species was absent in all the rifampin-susceptible species. rpoB-based phylogenetic relationships among these rickettsial species yielded topologies which were in accordance with previously published phylogenies.

Evolution, purification, and characterization of RC0497: a peptidoglycan amidase from the prototypical spotted fever species Rickettsia conorii

2020 ◽  
Vol 401 (2) ◽  
pp. 249-262 ◽  
Author(s):  
Jignesh G. Patel ◽  
Hema P. Narra ◽  
Krishna Mohan Sepuru ◽  
Abha Sahni ◽  
Sandhya R. Golla ◽  
...  
Keyword(s):  
Cell Wall ◽  
Spotted Fever ◽  
Protein A ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Purification And Characterization ◽  
E Coli ◽  
Binding Domains ◽  
Α Helix

AbstractRickettsial species have independently lost several genes owing to reductive evolution while retaining those predominantly implicated in virulence, survival, and biosynthetic pathways. In this study, we have identified a previously uncharacterized Rickettsia conorii gene RC0497 as an N-acetylmuramoyl-L-alanine amidase constitutively expressed during infection of cultured human microvascular endothelial cells at the levels of both mRNA transcript and encoded protein. A homology-based search of rickettsial genomes reveals that RC0497 homologs, containing amidase_2 family and peptidoglycan binding domains, are highly conserved among the spotted fever group (SFG) rickettsiae. The recombinant RC0497 protein exhibits α-helix secondary structure, undergoes a conformational change in the presence of zinc, and exists as a dimer at higher concentrations. We have further ascertained the enzymatic activity of RC0497 via demonstration of its ability to hydrolyze Escherichia coli peptidoglycan. Confocal microscopy on E. coli expressing RC0497 and transmission immunoelectron microscopy of R. conorii revealed its localization predominantly to the cell wall, septal regions of replicating bacteria, and the membrane of vesicles pinching off the cell wall. In summary, we have identified and functionally characterized RC0497 as a peptidoglycan hydrolase unique to spotted fever rickettsiae, which may potentially serve as a novel moonlighting protein capable of performing multiple functions during host-pathogen interactions.

scholarly journals Significant Growth by Rickettsia Species within Human Macrophage-Like Cells Is a Phenotype Correlated with the Ability to Cause Disease in Mammals

Pathogens ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 228
Author(s):  
M. Nathan Kristof ◽  
Paige E. Allen ◽  
Lane D. Yutzy ◽  
Brandon Thibodaux ◽  
Christopher D. Paddock ◽  
...  
Keyword(s):  
Endothelial Cells ◽  
Spotted Fever ◽  
Growth Characteristic ◽  
Human Macrophage ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Rocky Mountain Spotted Fever ◽  
Phagocytic Cells ◽  
Pathogenic Potential ◽  
Rickettsia Species

Rickettsia are significant sources of tick-borne diseases in humans worldwide. In North America, two species in the spotted fever group of Rickettsia have been conclusively associated with disease of humans: Rickettsia rickettsii, the causative agent of Rocky Mountain spotted fever, and Rickettsia parkeri, the cause of R. parkeri rickettsiosis. Previous work in our lab demonstrated non-endothelial parasitism by another pathogenic SFG Rickettsia species, Rickettsia conorii, within THP-1-derived macrophages, and we have hypothesized that this growth characteristic may be an underappreciated aspect of rickettsial pathogenesis in mammalian hosts. In this work, we demonstrated that multiple other recognized human pathogenic species of Rickettsia, including R. rickettsii, R. parkeri, Rickettsia africae, and Rickettsiaakari can grow within target endothelial cells as well as within PMA-differentiated THP-1 cells. In contrast, Rickettsia bellii, a Rickettsia species not associated with disease of humans, and R. rickettsii strain Iowa, an avirulent derivative of pathogenic R. rickettsii, could invade both cell types but proliferate only within endothelial cells. Further analysis revealed that similar to previous studies on R. conorii, other recognized pathogenic Rickettsia species could grow within the cytosol of THP-1-derived macrophages and avoided localization with two different markers of lysosomal compartments; LAMP-2 and cathepsin D. R. bellii, on the other hand, demonstrated significant co-localization with lysosomal compartments. Collectively, these findings suggest that the ability of pathogenic rickettsial species to establish a niche within macrophage-like cells could be an important factor in their ability to cause disease in mammals. These findings also suggest that analysis of growth within mammalian phagocytic cells may be useful to predict the pathogenic potential of newly isolated and identified Rickettsia species.

scholarly journals Characterization of a spotted fever group Rickettsia from Ixodes ricinus ticks in Sweden.

1997 ◽  
Vol 35 (1) ◽  
pp. 243-247 ◽  
Author(s):  
K Nilsson ◽  
T G Jaenson ◽  
I Uhnoo ◽  
O Lindquist ◽  
B Pettersson ◽  
...  
Keyword(s):  
Ixodes Ricinus ◽  
Spotted Fever ◽  
Spotted Fever Group ◽  
Ixodes Ricinus Ticks ◽  
Spotted Fever Group Rickettsia

Detection and characterization of a novel spotted fever group Rickettsia genotype in Haemaphysalis leporispalustris from California, USA

2018 ◽  
Vol 9 (4) ◽  
pp. 814-818 ◽  
Author(s):  
Marina E. Eremeeva ◽  
Lindsey M. Weiner ◽  
Maria L. Zambrano ◽  
Gregory A. Dasch ◽  
Renjie Hu ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Spotted Fever Group ◽  
Spotted Fever Group Rickettsia

POSSIBILITY OF SEROLOGICAL VERIFICATION OF SIBERIAN TICK TYPHUS WITH THE TEST SYSTEM FOR IDENTIFICATION OF RICKETTSIA CONORII ANTIBODIES

2019 ◽  
Vol 64 (9) ◽  
pp. 553-559
Author(s):  
N. V. Rudakov ◽  
S. V. Shtrek ◽  
A. I. Blokh ◽  
N. A. Penjevskaya ◽  
L. D. Shchuchinova
Keyword(s):  
Clinical Symptoms ◽  
Spotted Fever ◽  
Laboratory Diagnosis ◽  
Test System ◽  
Elisa Test ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Igm Antibodies ◽  
Negative Results ◽  
Sensitivity Specificity

The real epidemiological impact of Spotted Fever Group rickettsioses including Siberian tick-borne typhus (STT) in Russia is not sufficiently studied. One of the reasons is the actual absence of either certified domestic diagnostic kits or the evidence for using foreign test kits for laboratory verification of this group of tick-borne infections in medical practice. Objective of our study was to study the diagnostic accuracy of the ELISA test system based on Rickettsia conorii antigens for serological verification of STT. The ROC analysis was performed and operational characteristics (sensitivity, specificity, accuracy, likelihood ratio of positive and negative results) of the STT serological verification test to identify IgM to rickettsia at different times from the onset of the disease using a test system to detect antibodies to Rickettsia conorii were calculated based on the results of a survey of two groups of patients comparable by gender and age (34 patients with pathognomonic signs of STT and 76 clinically healthy people). It was found that the detection of IgM antibodies to rickettsia using the Rickettsia conorii IgM/IgG ELISA test system (Vircell) allows the disease to be verified 10-14 days after the onset of clinical symptoms in 72% (56-88%) of STT patients. We recommend the interpretation of results of the test system “Rickettsia conorii ELISA IgM/IgG” for serological verification of STT which differ from the manufacturer’s recommendations regarding verification of Mediterranean fever caused by R. conorii in the following way: the diagnosis of STT should be considered laboratory confirmed when the index of IgM antibodies (IAT) exceeds 8.0; if the IAT is less than 5.0 then a repeated examination of the patient after 10-14 days will be necessary; if the IAT is in the range of 5.0-8.0 then the sample should be re-examined and / or the patient should be examined after 10-14 days. The use of the test system “Rickettsia conorii ELISA IgM / IgG” is promising for laboratory diagnosis and seroepidemiological studies of Spotted Fever Group rickettsioses in Russia.

scholarly journals Characterization of Spotted Fever Group Rickettsiae Detected in Dogs and Ticks in Okinawa, Japan

2002 ◽  
Vol 46 (4) ◽  
pp. 257-263 ◽  
Author(s):  
Hiroshi Satoh ◽  
Yurie Motoi ◽  
Gerry A. Camer ◽  
Hisashi Inokuma ◽  
Masako Izawa ◽  
...  
Keyword(s):  
Spotted Fever ◽  
Spotted Fever Group ◽  
Spotted Fever Group Rickettsiae

scholarly journals Taxonomic Relationships among Spotted Fever Group Rickettsiae as Revealed by Antigenic Analysis with Monoclonal Antibodies

1998 ◽  
Vol 36 (4) ◽  
pp. 887-896 ◽  
Author(s):  
Wenbin Xu ◽  
Didier Raoult
Keyword(s):  
Monoclonal Antibodies ◽  
Phylogenetic Analyses ◽  
Spotted Fever ◽  
Rickettsia Conorii ◽  
Spotted Fever Group ◽  
Antigenic Analysis ◽  
Taxonomic Relationships ◽  
Rickettsia Africae ◽  
Rickettsia Slovaca ◽  
Rickettsia Sibirica

The spotted fever group (SFG) is made up of more than 20 different rickettsial species and strains. Study of the taxonomic relationships among the group has been attempted by phenotypic, genotypic, and phylogenetic analyses. In this study, we determined taxonomic relationships among the SFG rickettsiae by comparative analysis of immunogenic epitopes reactive against a panel of monoclonal antibodies. A total of 98 monoclonal antibodies, which were directed against epitopes on the major immunodominant proteins or on the lipopolysaccharide-like antigens of strains of Rickettsia africae, Rickettsia conorii, Rickettsia massiliae, Rickettsia akari, Rickettsia sibirica, and Rickettsia slovaca, were used in the study. The distribution and expression of the epitopes among 29 SFG rickettsiae and Rickettsia bellii were assessed by determination of reaction titers in a microimmunofluorescence assay. The results were scored as numerical taxonomic data, and cluster analysis was used to construct a dendrogram. The architecture of this dendrogram was consistent with previous taxonomic studies, and the implications of this and other findings are discussed.

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