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.
Fingerprint' technique spots frog populations at risk from pollution
27.03.2017 | Lancaster University
Parallel computation provides deeper insight into brain function
27.03.2017 | Okinawa Institute of Science and Technology (OIST) Graduate University
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to simulate these confined natural conditions in artificial vesicles for the first time. As reported in the academic journal Small, the results are offering better insight into the development of nanoreactors and artificial organelles.
Enzymes behave differently in a test tube compared with the molecular scrum of a living cell. Chemists from the University of Basel have now been able to...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
27.03.2017 | Earth Sciences
27.03.2017 | Life Sciences
27.03.2017 | Life Sciences