Ehrlichiosis article shows how SNEAKY stealth paths really are

Discussion in 'Lyme Disease Archives' started by victoria, Jun 8, 2006.

  1. victoria

    victoria New Member

    The Institute for Genomic Research

    February 19, 2006

    Ticks, Flukes, And Genomics: Emerging Pathogens Revealed

    Ehrlichiosis is no star of science. This emerging disease has an awkward name, vague flu-like symptoms, and a nasty habit of being caused by bacteria that live inside ticks and flatworms. But in the current issue of the journal Public Library of Science Genetics (PLoS Genetics), scientists put ehrlichiosis under the genomic spotlight--and discover some brilliant biology.

    Led by scientists at The Institute for Genomic Research (TIGR) and The Ohio State University (OSU), a team of researchers report the complete genomes of three emerging pathogens that cause ehrlichiosis--Anaplasma phagocytophilum, Ehrlichia chaffeensis, and Neorickettsia sennetsu--and compare the genomes with those of 16 other bacteria with similar lifestyles.

    The study reports new genes that allow the bacteria to evade a host's immune system, adapt to new niches, and more. Finally, the report reconstructs the metabolic potential of five representative genomes from these bacteria.

    "By comparing so many different pathogens, some closely related and others diverse, we're able to identify genes linked to different diseases and organisms," explains molecular biologist Julie Dunning Hotopp of TIGR, first author of the PLoS Genetics paper.

    Because the pathogens causing ehrlichiosis are obligate intracellular bacteria--able to thrive only inside host cells--they are hard to isolate and study in the lab, Hotopp adds.

    "How are these diseases different? How are they the same? Can we correlate certain genes with certain characteristics? For the first time, our comparative genomics database offers a resource for tackling these questions."

    Recognized since at least the 1930s, ehrlichiosis sickens not only humans, but also dogs, cattle, sheep, and other animals. In Japan, human ehrlichiosis is commonly called sennetsu fever. In the U.S., most human cases have been linked to ticks.

    In the new study, scientists uncovered a clue to how ehrlichiosis-causing bacteria infect such diverse animals. One of the three primary bacteria sequenced, A. phagocytophilum, contains roughly 1,400 genes--including MORE than 100 VARIATIONS OF A SINGLE GENE THAT CODES FOR A PROTEIN ALLOWING THE BACTERIA TO EVADE THEIMMUNE SYSTEM OF THE ORGANISM IT HAS INFECTED.

    This protein sits on the bacteria's outer membrane surface. When the bacteria,through tick bites, transfers to a human, say, or horse, the bacteria CHOOSES the protein variation needed to stay hidden from that particular host.

    "These genome sequences have revolutionized the types of experiments [scientists] can perform to understand these diseases," says microbiologist Yasuko Rikihisa of OSU's College of Veterinary Medicine. "Already, at least four labs are performing, or planning to perform, whole genome DNA microarray analysis and proteomic analysis of these bacteria."

    In addition to comparing genomes, the current study used those genomes to reconstruct the metabolic potential (the ability to use and produce energy and compounds) of five bacteria, representing the numerous organisms compared. With this final analysis, they gleaned new insight into the broader tactics used by different bacteria.


    "This study is a beautiful example of how in-depth comparative genomics can lead to the identification of molecular features that underlie the lifestyle of pathogens," says TIGR molecular biologist Hervé Tettelin, senior author of the PLoS Genetics article.

    "We could not have reached these conclusions by independently studying the genome sequence of each individual pathogen," he adds. "Now we know how some of the pathogens studied infect or provide benefits to their hosts."

    The scientists hope to build on this work, with potential studies to determine which bacterial genes are turned on during ehrlichiosis infection and to track the evolutionary differences between ehrlichiosis-causing organisms in different parts of the world. Other scientists can build on the new work as well, by accessing the comparative database now online at This genome sequencing project work was funded by the National Institutes of Health.


    The Institute for Genomic Research is a not-for-profit center dedicated to deciphering and analyzing genomes. Since 1992, TIGR, based in Rockville, Md., has been a genomics leader, conducting research critical to medicine, agriculture, energy, the environment and biodefense.

    Copyright © 1995-2006 ScienceDaily LLC
    [This Message was Edited on 06/08/2006]
  2. jarjar

    jarjar New Member

    Good Post Victoria 06/08/06 09:40 AM

    I learned from my last lyme doc visit that I probably have Echrilchiosis due to the fact I always have a low WBC.

    According to him that is a red flag. I can't even remember the last time I had a normal WBC. So eventually I will be off to Doxy land for starters to try to knock it out.

    Thought I would post this in case it rings a bell with any other lyme patients.

  3. pumpkinpatch

    pumpkinpatch New Member

    I wonder which abx they use for ehrlichiosis-. I just found out that the mepron for babesia will be covered under my plan.
  4. jarjar

    jarjar New Member

    When I mentioned I will off to doxy land I meant that I would be on Doxy to treat the Ehrlichiosis. That is usually the first drug used to treat it.

    You might want to check how long your doc wants your to stay on mepron and how long your insurance company will pay for it as I've heard that it cost anywhere from 800.00 on up a month to take. Sometimes insurance will put a cap on how many months they will pay for an expensive ABX.

  5. Kimelia

    Kimelia New Member

    I wish my brain were capable of understanding this article right now....
  6. victoria

    victoria New Member

    what I do is print off what I can't read or understand... somehow sitting down in a comfy chair and taking my time AND reading from a paper copy rather than computer screen seems easier usually.