Some species of Rickettsia are known to cause harmful diseases in humans, such as epidemic typhus (R. prowazekii) and Rocky Mountain spotted fever (R. rickettsii), while others have been identified as emerging pathogens and critical agents for the development of bioweapons. The Rickettsia felis bacterium has in some cases been linked to the onset of typhus-like disease in humans. Until now, it has been difficult to fit R. felis into the evolutionary picture of the rickettsia in part due to the presence of a “hard to classify” plasmid or gene-carrying element not found in the other rickettsiae.
Dr. Joseph Gillespie, a bioinformatician at the Virginia Bioinformatics Institute and the lead author of the paper, remarked: “By comparing sequences and using bioinformatic tools, we have been able to demonstrate that there is indeed strong support for the presence of a single plasmid in R. felis, and that many of the plasmid genes have probably been horizontally inherited from exchanges with other organisms. We have also been able to go one step further and show that the primitive rickettsial ancestor itself likely harbored plasmids of this type which has important implications for the evolutionary origin of the group.”
The traditional rickettsial classification system divides members of the genus into three categories – spotted fever group, typhus group, and ancestral group. However, the genome sequence of R. felis shows inconsistencies that could place it in either the spotted fever or typhus groups. The new classification system highlighted in the study includes the addition of a fourth lineage—transitional group rickettsia—that provides a framework to support some of the known evolutionary relationships of these diverse bacteria. Specifically, the results offer insight into the evolution of a plastic plasmid system in rickettsiae, which includes the role plasmids may have played in the acquirement of virulence traits in pathogenic strains, and the likely origin of plasmids within the rickettsial evolutionary tree.
VBI Director and PATRIC Principal Investigator Bruno Sobral remarked: “The role plasmids play in host colonization and virulence is not well understood, and will likely only become more apparent with the discovery of plasmids in other rickettsiae. We hope that an evolutionary perspective coupled with the characterization of the contributions of these plasmids to host recognition, invasion and pathogenicity will open up exciting new research opportunities for the virulent rickettsiae. One of the goals of the PATRIC project is to enable the future development of much needed diagnostics and vaccines for a wide range of diseases. The research described in this study is a good example of how developments in evolutionary classification, for example, can help facilitate the objectives of the PATRIC project.”
VBI researchers Joseph Gillespie, Joshua Shallom, Anjan Purkayastha, and Bruno Sobral, along with University of Maryland colleagues Magda Beier, Mohammed S. Rahman, Nicole C. Ammerman, and Abdu F. Azad (PATRIC organism expert and senior author) contributed to the paper, “Plasmids and Rickettsial Evolution: Insight from Rickettsia felis.” The paper will be featured in the March 7, 2007 edition of the online publication PLoS ONE.
Toward a 'smart' patch that automatically delivers insulin when needed
18.01.2017 | American Chemical Society
127 at one blow...
18.01.2017 | Stiftung Zoologisches Forschungsmuseum Alexander Koenig, Leibniz-Institut für Biodiversität der Tiere
Yersiniae cause severe intestinal infections. Studies using Yersinia pseudotuberculosis as a model organism aim to elucidate the infection mechanisms of these...
Researchers from the University of Hamburg in Germany, in collaboration with colleagues from the University of Aarhus in Denmark, have synthesized a new superconducting material by growing a few layers of an antiferromagnetic transition-metal chalcogenide on a bismuth-based topological insulator, both being non-superconducting materials.
While superconductivity and magnetism are generally believed to be mutually exclusive, surprisingly, in this new material, superconducting correlations...
Laser-driving of semimetals allows creating novel quasiparticle states within condensed matter systems and switching between different states on ultrafast time scales
Studying properties of fundamental particles in condensed matter systems is a promising approach to quantum field theory. Quasiparticles offer the opportunity...
Among the general public, solar thermal energy is currently associated with dark blue, rectangular collectors on building roofs. Technologies are needed for aesthetically high quality architecture which offer the architect more room for manoeuvre when it comes to low- and plus-energy buildings. With the “ArKol” project, researchers at Fraunhofer ISE together with partners are currently developing two façade collectors for solar thermal energy generation, which permit a high degree of design flexibility: a strip collector for opaque façade sections and a solar thermal blind for transparent sections. The current state of the two developments will be presented at the BAU 2017 trade fair.
As part of the “ArKol – development of architecturally highly integrated façade collectors with heat pipes” project, Fraunhofer ISE together with its partners...
At TU Wien, an alternative for resource intensive formwork for the construction of concrete domes was developed. It is now used in a test dome for the Austrian Federal Railways Infrastructure (ÖBB Infrastruktur).
Concrete shells are efficient structures, but not very resource efficient. The formwork for the construction of concrete domes alone requires a high amount of...
10.01.2017 | Event News
09.01.2017 | Event News
05.01.2017 | Event News
18.01.2017 | Power and Electrical Engineering
18.01.2017 | Materials Sciences
18.01.2017 | Life Sciences