Navigation Links
How Rickettsial pathogens break into cells

New research by a team of scientists in France and the United States has identified both the bacterial and host receptor proteins that enable Rickettsia conorii, the Mediterranean spotted fever pathogen, to enter cells. Understanding how this bacterium interacts with the cells of its host could lead to new therapeutic strategies for diseases caused by related pathogens, including Rocky Mountain spotted fever and typhus.

Pascale Cossart, an HHMI international research scholar at the Pasteur Institute in Paris, together with her postdoctoral fellow Juan Martinez and collaborators in Paris and at Case Western Reserve University in Cleveland, Ohio, has identified the first receptor for a Rickettsial bacterium. Their findings will be reported in the December 16, 2005, issue of the journal Cell.

Rickettsial bacteria are transmitted by fleas, ticks, and lice to humans and other mammals, where they can cause dangerous and sometimes fatal infections. There are two types of Rickettsial pathogens--the spotted fever group, which includes the Rickettsia conorii bacteria studied by Cossart and her colleagues, and the typhus group. Both must live inside cells to survive. Rickettsia have been classified by the National Institute of Allergy and Infectious Diseases (NIAID) as agents with potential for use as tools for bioterrorism.

Mediterranean spotted fever is transmitted by a dog tick. The symptoms are generally mild and respond to antibiotics that shorten the course of the disease. But serious complications occur as much as 10 percent of the time, usually in patients who are elderly or who have some other underlying disease. Left untreated, Mediterranean spotted fever can be deadly.

Cossart and her team demonstrated that the Ku70 protein on the surface of host cells is critical for R. conorii to enter the cell, making it the first Rickettsial receptor ever identified. "This receptor is a subunit of a protein complex present mainly in the nucleus, but also in the cell cytoplasm and at the cell membrane," said Cossart. "We have thus used several approaches to establish our findings definitively." Ku70 is probably not the only receptor involved in bacterial entry, she noted.

The researchers found that R. conorii specifically binds to Ku70, and that binding and recruitment of Ku70 at the surface of the host cell are important events in R. conorii's invasion of mammalian cells. In addition, since Ku70 has previously been shown to control cell death, the new findings suggest that Rickettsia, which--like several other intracellular parasites--prevent cell death in order to multiply inside living cells, may also use this property of their receptor for a succesful infection

"We found that Ku70 interacts with a bacterial protein called rOmpB, which is present on the surface of Rickettsia bacteria," Cossart said. "The mechanism underlying this interaction remains unclear, so we are now investigating how rOmpB, expressed by R. conorii, interacts with Ku70 and allows bacterial entry."

Her team has already shown that Ku70 has to be present in certain well-organized regions of the cell membrane called rafts, and that the protein modifier called ubiquitin modifies Ku70 as soon as the bacteria interact with it. This step is critical for cell entry. "Whether other Rickettsia and other pathogens use Ku70 as a receptor is still unknown," Cossart said.


'"/>

Source:Howard Hughes Medical Institute


Related biology news :

1. A new study examines how shared pathogens affect host populations
2. New lab technique identifies high levels of pathogens in therapy pool
3. Edible bivalves as a source of human pathogens: signals between vibrios and the bivalve host.
4. Tagging pathogens with synthetic DNA barcodes
5. Study: Plants use dual defense system to fight pathogens
6. CO2 sensing proves critical for fungal pathogens to adapt to life in air and human hosts
7. Ticks, flukes, and genomics: Emerging pathogens revealed
8. Gene thwarts some pathogens, gives access to others, could save crops
9. Researchers map spread of pathogens in the human body
10. Researchers develop technologies to devour food pathogens
11. GreeneChip -- New diagnostic tool that rapidly and accurately identifies multiple pathogens
Post Your Comments:
*Name:
*Comment:
*Email:


(Date:4/28/2016)... BANGALORE, India , April 28, 2016 /PRNewswire/ ... product subsidiary of Infosys (NYSE: INFY ), and ... global partnership that will provide end customers with ... banking and payment services.      (Logo: http://photos.prnewswire.com/prnh/20130122/589162 ... area for financial services, but it also plays a fundamental ...
(Date:4/28/2016)... GOTHENBURG, Sweden , April 28, 2016 ... 1,491.2 M (139.9), up 966% compared with the first quarter of ... Operating profit totaled SEK 589.1 M (loss: 18.8) and the operating ... SEK 7.12 (loss: 0.32) Cash flow from operations was ... , The 2016 revenue guidance is unchanged, SEK 7,000-8,500 M. ...
(Date:4/26/2016)... and LONDON , April ... part of EdgeVerve Systems, a product subsidiary of ... today announced a partnership to integrate the Onegini ...      (Logo: http://photos.prnewswire.com/prnh/20151104/283829LOGO ) ... their customers enhanced security to access and transact ...
Breaking Biology News(10 mins):
(Date:4/27/2016)... ... April 27, 2016 , ... Cambridge Semantics, the ... technology, today announced that it has been named to The Silicon Review’s “20 Fastest ... and other markets, Cambridge Semantics serves the needs of end users facing some of ...
(Date:4/27/2016)... ... April 27, 2016 , ... Most consumers engage with biometrics ... for secure access, voice recognition for hands-free communication, and facial recognition to help ... biometrics technology today. But if they asked Joey Pritikin, Vice President of ...
(Date:4/27/2016)... ... April 27, 2016 , ... The Board of Directors ... of John Tilton as Chief Commercial Officer.  Mr. Tilton joined Biohaven from Alexion ... commercial leaders responsible for the commercialization of multiple orphan drug indications. Mr. ...
(Date:4/27/2016)... ... April 27, 2016 , ... A compact PET scanner ... and MRI (Magnetic Resonance Imaging) in existing third-party MRI systems. PET and MRI ... small animal subjects. Simultaneous PET/MRI imaging offers a solution to many challenges that ...
Breaking Biology Technology: