Lyme disease, science, and society: Camp Other
Showing posts with label macdonald. Show all posts
Showing posts with label macdonald. Show all posts

Friday, February 17, 2012

6 Paper On Borrelia burgdorferi, RpoS, And Formation of Round Bodies or "Cysts"

Dr. MacDonald just posted information on Lymenet Europe concerning a new paper by Dunham-Emsl et al about the round body aka "cyst" form of Borrelia burgdorferi as part of the Lyme disease life cycle within the tick.

The indication here is that Borrelia burgdorferi assumes a round body form within the tick in order to survive until circumstances for transmission to the host are present. There is no confirmation here, however, of its formation in vivo within a host mammal...

Full Text Source: http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1002532

Borrelia burgdorferi Requires the Alternative Sigma Factor RpoS for Dissemination within the Vector during Tick-to-Mammal Transmission

Star M. Dunham-Ems, Melissa J. Caimano, Christian H. Eggers, Justin D. Radolf

Abstract

While the roles of rpoSBb and RpoS-dependent genes have been studied extensively within the mammal, the contribution of the RpoS regulon to the tick-phase of the Borrelia burgdorferi enzootic cycle has not been examined. Herein, we demonstrate that RpoS-dependent gene expression is prerequisite for the transmission of spirochetes by feeding nymphs. RpoS-deficient organisms are confined to the midgut lumen where they transform into an unusual morphotype (round bodies) during the later stages of the blood meal. We show that round body formation is rapidly reversible, and in vitro appears to be attributable, in part, to reduced levels of Coenzyme A disulfide reductase, which among other functions, provides NAD+ for glycolysis. Our data suggest that spirochetes default to an RpoS-independent program for round body formation upon sensing that the energetics for transmission are unfavorable.



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0 Phage-holder

Rather than use the term "placeholder" I decided to use "phage-holder" because this post is going to be all about bacteriophage and phage therapy.

First, I came across this Nature blog post from Jim Caryl from last April - "No action today, no antibiotics tomorrow..." It outlines the serious problem of growing antibiotic resistance to infection and proposes different technological solutions for combatting resistance.

Jim advocates the revamping of our current drug manufacturing system to produce new antimicrobial therapies based on new targets as well as remodeling old antibiotics with high toxicity so that they are less toxic. He is not as enthusiastic about the application of phage therapy, citing a need for more efficacy testing and double blind random control trials. Those who commented on his blog, though, are strongly in support of phage therapy and think it has much promise.

 If you are a Lyme disease patient (or care about someone who is) then his fourth item on his anti-microbials-of-the-future list may interest you - if the data is there to support persister cells as part of Borrelia burgdorferi's pathogenesis:
"The current model for drug discovery is towards drugs that interfere with actively growing bacteria, however, bacteria aren't always actively growing. I've written before about how being in a different growth-phase can render a bacterial cell resistant to antibiotics. This can lead to repeated flare-ups of the infection until, eventually, true genetic resistance evolves that allows the bacteria to survive, and continue growing in the presence of the antibiotic. Thus there is the proposal that as part of enhanced efforts in drug discovery, that a platform for developing drugs at slow- or non-growing bacteria be practised."
Check out Jim's well-written post, and check out the comments.

Second, I periodically see what's new in terms of phage therapy education and outreach in the United States - and in particular, drop by Evergreen State College's (ESC - Olympia, WA) pages on bacteriophage research.

If you take an interest in learning more about phage therapy, this is a good place to start for an English-language based repository. On ESC's web site you can learn about phage research around the world, including at the well-known Eliava Institute in Tblisi, Georgia - and there are interesting links such as one to a new journal, Bacteriophage, the first international, peer-reviewed journal dedicated to all aspects of bacteriophage research, ranging from basic phage biology and taxonomy to advanced bacteriophage-host cell interactions and various practical applications of bacteriophages.

If this is really your thing, you might want to prepare for the next International Phage Biology Meeting in 2013, with more details  about this meeting to be announced here in the future: http://blogs.evergreen.edu/phage/

Third, little late to the game on this one - but I have news on the business side of phage therapy in the United States. I discovered the web site of this company, Amliphi Biosciences Corporation, which states "AmpliPhi Biosciences is the first company to demonstrate the clinical efficacy of phage technology in a controlled, regulated, human clinical trial."

While their focus is on researching bacteriophage therapy for resistant Gram-negative bacterial infections, there is currently no development underway for Borrelia burgdorferi infections (which if you'll recall is not exactly Gram-negative bacteria anyway). But the research they are doing may improve and save the lives of many people struggling with resistant bacterial infections such as children suffering from chronic ear infections and adults suffering from cystic fibrosis. In fact, AmpliPhi is receiving initial funding support from Cystic Fibrosis Foundation Therapeutics, Inc. (a nonprofit affiliate of the Cystic Fibrosis Foundation).

Check out their product pipeline page to learn more about the clinical trials they have been conducting on phage therapy for helping people with these conditions as well as for other purposes.

Last but not least, I wanted to announce that one of my own pages on bacteriophage will soon be updated due to a major oversight that was called to my attention through my recent exchanges with Dr. Alan MacDonald on Lymenet Europe. He posted some images of Dr. Alan Barbour's early research on Borrelia burgdorferi where a B-3-like phage was found on and in spirochetes (Why are there so many Allens or Alans doing research in this field?). This is research that definitely should have been included in this page and I am very remiss in not including it.

I also realize that part of it needs rewriting in general because a few basic concepts about how phage therapy works need to be included - including the fact that each phage is often very strain specific. My current writing suggests to the reader that one phage will handily kill all Borrelia burgdorferi when that is not so - though a genetically modified virus which attacks Borrelia might be altered in such a way as to inject different Borrelia with something that is disruptive to a common Borrelia target. Phages "in the wild" do not operate in this fashion - they are found and they evolve on their own and are strain specific. So expect this page to be updated to include this information soon.

One may wonder why Camp Other is so interested in bacteriophage therapy. The reason is simple: There may be some way in the future to detect which strains of Borrelia someone has been infected with at the site of a tick bite and develop a phage-based ointment that will prevent infection from disseminating. It will do so without the problem of antibiotic resistance cropping up and without all the horrible side effects that antibiotics can bring including the risk of contracting C. difficile.

So I would very much like to see this be made possible, though there are inherent difficulties in finding lytic phages for Borrelia and the issue that "handedness" ("male"/"female") of the bacteria is related to finding effective phages, much like the "handedness" of sugars has different effects in the human body.


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Wednesday, February 8, 2012

1 Memo: Borrelia Are NOT Gram-Negative Bacteria, And Might Become Resistant

For years, Borrelia have been thought to be Gram-negative because of their diderm and structural appearance upon staining. Borrelia - including Borrelia burgdorferi - are not Gram-negative bacteria, though - even though many people are still referring to them as such. They belong in their own category.

As I was telling Dr. MacDonald this week:
I found information confirming the fact that Borrelia is not Gram-negative or Gram-positive. It's its own special thing:

"Borrelia were thought to be Gram negative because of their double membrane structure, but genetic analysis places them - along with other spirochetes - into a separate eubacterial phylum. Ultrastructural molecular and biochemical studies have emphasized the wide taxonomic gap between spirochetes and Gram-negative bacteria."

- From "The Genus Borrelia" by Melissa Caimano. Prokaryotes (2006) 7:235-293.

"Although Borrelia spirochetes are often, but mistakenly described as Gram-negative bacteria due to their diderm, i.e. double-membrane envelopes, a closer examination reveals significant differences in composition and architecture. Probably most striking is the lack of LPS, the presence of major surface lipoproteins at the host-pathogen interface during transmission, persistence and ensuing pathogenic processes and the additional function of periplasmic flagella in defining cell shape. While surface lipoproteins such as the Osps interact with a variety of ligands in different organ tissues, they are also targets of the immune response and several have emerged as vaccine candidates."

- From Borrelia: Molecular Biology, Host Interaction and Pathogenesis. Edited by D. Scott Samuels and Justin D. Radolf. (2010)

So one could say they are Gram-negative-"like" - but strictly speaking, Borrelia is not Gram-negative bacteria."
He accepted this response, and is now stating that Borrelia burgdorferi is Gram-indeterminate.

There is additional information from the second source cited which indicates that Borrelia spirochetes are different from other bacteria, summarized here:
"Some of the identified periplasmic lipoproteins, i.e. the OppAs, are components of substrate transport complexes. Investigations into integral membrane proteins led to the identification of several Borrelia porins: P13, whose structure and function is unknown, DipA, which is specific for dicarboxylates and P66 (Oms66), which has a dual role as a pore-forming outer membrane protein with an extremely high single channel conductance and an adhesin for β3-integrin. The recently identified Tol homologs BesA, -B and -C appear to form a Type I 'channel' to export exogenous toxic agents such as antibiotics and to maintain infectivity by an unknown mechanism. Initial studies on envelope biogenesis pathways based on diderm proteobacterial model organisms already revealed significant deviations from the norm. This further bolsters the unique status of Borrelia among microbial pathogens."
Damn Borrelia... Why do you have to be such a deviant? Why can't you just conform?

Anyway, the Type I 'channel' they're talking about above which exports or removes antibiotics and helps maintain infectivity is said here to do so using an unknown mechanism. Judging from research out there, this channel relates to transmembrane proteins which span the outer and inner membranes of the bacteria - and it appears to function like an efflux pump (in this case, a resistance-nodulation-division-like pump) which removes antibiotics and is involved in antibiotic resistance. Check out this paper (full text at link):

Source: http://www.plospathogens.org/article/info%3Adoi%2F10.1371%2Fjournal.ppat.1000009

An RND-Type Efflux System in Borrelia burgdorferi Is Involved in Virulence and Resistance to Antimicrobial Compounds

Ignas Bunikis1, Katrin Denker, Yngve Östberg1, Christian Andersen, Roland Benz, Sven Bergström. PLoS Pathog. 2008 Feb 29;4(2):e1000009.

Abstract

Borrelia burgdorferi is remarkable for its ability to thrive in widely different environments due to its ability to infect various organisms. In comparison to enteric Gram-negative bacteria, these spirochetes have only a few transmembrane proteins some of which are thought to play a role in solute and nutrient uptake and excretion of toxic substances. Here, we have identified an outer membrane protein, BesC, which is part of a putative export system comprising the components BesA, BesB and BesC. We show that BesC, a TolC homolog, forms channels in planar lipid bilayers and is involved in antibiotic resistance. A besC knockout was unable to establish infection in mice, signifying the importance of this outer membrane channel in the mammalian host. The biophysical properties of BesC could be explained by a model based on the channel-tunnel structure. We have also generated a structural model of the efflux apparatus showing the putative spatial orientation of BesC with respect to the AcrAB homologs BesAB. We believe that our findings will be helpful in unraveling the pathogenic mechanisms of borreliae as well as in developing novel therapeutic agents aiming to block the function of this secretion apparatus.



Obviously, more research in this direction is necessary.

So when people ask, "Camp, why are you so interested in learning about something like TolC? Why don't you want to learn about different kinds of treatment and how they've helped patients?" my answer for them is this:

I do want to learn about different kinds of treatment - it is in my best interest to do so, given I have been dealing with Lyme-related health problems for years. And I make my own decisions about treatment which are largely personal to my situation.

But learning this stuff - these details tucked away in what must appear to most people to be obscure publications in little-known journals outside of researchers within the field? To me, this stuff is what may get us all closer to better treatment for many people.

Do I know this for sure? No. No one does. But with some of the specifics under my belt, I can then at least petition the science world and advocate for the funding to do research on some very particular subjects to get very specific knowledge. Knowledge which may give us a solid idea as to how to treat chronic Lyme disease so that it doesn't become chronic.


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Monday, January 16, 2012

0 Dr. Alan MacDonald Discussing Spirochetal Biofilms on LNE

There are a series of discussions going on right now on Lymenet Europe I want to point out.

It looks like Dr. Alan Macdonald is having an involved exchange about biofilms in different spirochetes with someone (Henry) who has identified as a microbiologist in previous entries.

You might want to check out this thread now:

Biofilms of still yet spirochetal type - Treponema:
http://www.lymeneteurope.org/forum/viewtopic.php?f=5&t=3607

Also follow the following related threads:

Structure of Biofilms of Borrelia Lecture link:
http://www.lymeneteurope.org/forum/viewtopic.php?f=5&t=3602

Biofilms of yet another spirochetal species - Leptospira:
http://www.lymeneteurope.org/forum/viewtopic.php?f=5&t=3606

I would like to see more doctors and microbiologists engage in discussion about Borrelia and other spirochetes more often - especially if the implications have an impact on translational medicine and clinical outcome. Obviously some of this discussion is going to be purely speculative, but it is interesting to hear different points of view.

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The Camp Other Song Of The Month


Why is this posted? Just for fun!

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