Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Chaining up diarrhea pathogens

19.04.2017

Vaccinations are known to protect against pathogens such as bacteria or viruses. They direct the body to form protective antibodies (IgA), and have been successfully used against some intestinal infections.

However, exactly how intestinal antibodies - known as secretory IgA - protect against infections was previously unclear. A group of researchers led by ETH Senior Assistant Emma Slack, have now used the example of salmonella-based diarrhoea to show that secretory IgA works very differently to how we previously assumed.


Antibody enchain Salmonella (green). This prevents the transfer of DNA (yellow rings) to other cells. The violet cells are swimming freely.

Credit: Thierry Sollberger

In a study published recently in the journal Nature, the researchers showed that vaccine-induced IgA effectively "enchained" the pathogens in the intestine: IgA binds the bacteria's daughter cells to each other during cell division. Although the enchained bacteria can continue to multiply, all their offspring remain trapped in these clumps. This clumping of genetically homogeneous bacteria prevents the attack of the intestinal tissue, accelerates the excretion of the pathogen and prevents genetic exchange between bacteria enchained in different clumps.

Agglutination only in the test tube

That antibodies and bacteria clump, a process known as agglutination, has long been known. However, this only occurs when antibodies and bacteria are present in high densities and so often come into contact with each other. "In the test tube, it happens in textbook fashion. There are high enough concentrations of antibodies and bacteria, so they often collide," says Dr. Slack.

In the intestine, however, such high pathogen densities are the exception: "this makes it much less likely that the IgA-coated bacteria will collide," explains Dr. Slack. Despite this, research has long observed that such clumps do form in the intestine - meaning there must have been another explanation for the clumping.

Bacterial growth controls clumping

Dr. Slack and her group have now demonstrated for the first time that clumps form even with a low pathogen density, and that this does not depend on the concentration of the bacteria. The driving force behind the formation of the clumps is the pathogens' growth rate. The IgA antibodies attach themselves so strongly to bacteria that they do not release them even when the pathogens divide. Thus both daughter cells remain stuck together. In this way, the IgA antibodies enchain all the offspring of a single, rapidly dividing bacterium.

Clumps hinder disease

"The clever thing about clump formation is that the antibodies don't kill the bacteria, which in the worst case could lead to a violent immune response. They simply prevent the microbes from interacting with the host, among themselves or with close relatives," says Wolf-Dietrich Hardt, Professor of Microbiology at ETH Zurich, who played a key role in the study.

Fighting intestinal infections using vaccination thus has several advantages: antibody-bacteria clumps cannot approach the intestinal wall, which prevents the intestinal mucosa from becoming inflamed. The intestine also gets rid of the clumps quickly, and after a few days they are cleared in the faeces. "The system is efficient. It is easier to get rid of a whole clump than to capture and eliminate many individual bacterial cells," says Dr. Slack.

No exchange of resistance genes

Intestinal vaccination could help to overcome the antibiotic resistance crisis. Vaccination decreases the incidence of diseases potentially requiring antibiotic usage, which would automatically reduce the development and spread of resistance to antibiotics.

IgA-driven clump formation also directly prevents genetic exchange between individual captured bacterial populations. Bacteria often exchange genes in the form of plasmids (ring-shaped DNA molecules), which frequently carry the feared antibiotic resistance genes. To exchange plasmids, however, the bacterial cells have to touch, which they can't do if they are stuck in separate clumps.

Livestock vaccination

The researchers used oral vaccines made from killed salmonella and E. coli bacteria. They suggested that this strategy could also be used against the pathogens of other intestinal diseases such as Shigella or Listeria.

The largest area of application for salmonella vaccination could be in farm animals such as pigs, which often act as a reservoir for antibiotic-resistant pathogens. Humans can become infected by contact with these animals and their raw meat. A vaccination for humans could also be feasible, which would benefit people working in disaster or epidemic areas, or those travelling in regions where bowel infections are common.

Emma Slack | EurekAlert!

More articles from Life Sciences:

nachricht Rochester scientists discover gene controlling genetic recombination rates
23.04.2018 | University of Rochester

nachricht One step closer to reality
20.04.2018 | Max-Planck-Institut für Entwicklungsbiologie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

Im Focus: Gamma-ray flashes from plasma filaments

Novel highly efficient and brilliant gamma-ray source: Based on model calculations, physicists of the Max PIanck Institute for Nuclear Physics in Heidelberg propose a novel method for an efficient high-brilliance gamma-ray source. A giant collimated gamma-ray pulse is generated from the interaction of a dense ultra-relativistic electron beam with a thin solid conductor. Energetic gamma-rays are copiously produced as the electron beam splits into filaments while propagating across the conductor. The resulting gamma-ray energy and flux enable novel experiments in nuclear and fundamental physics.

The typical wavelength of light interacting with an object of the microcosm scales with the size of this object. For atoms, this ranges from visible light to...

Im Focus: Basel researchers succeed in cultivating cartilage from stem cells

Stable joint cartilage can be produced from adult stem cells originating from bone marrow. This is made possible by inducing specific molecular processes occurring during embryonic cartilage formation, as researchers from the University and University Hospital of Basel report in the scientific journal PNAS.

Certain mesenchymal stem/stromal cells from the bone marrow of adults are considered extremely promising for skeletal tissue regeneration. These adult stem...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

Structured light and nanomaterials open new ways to tailor light at the nanoscale

23.04.2018 | Physics and Astronomy

On the shape of the 'petal' for the dissipation curve

23.04.2018 | Physics and Astronomy

Clean and Efficient – Fraunhofer ISE Presents Hydrogen Technologies at the HANNOVER MESSE 2018

23.04.2018 | Trade Fair News

VideoLinks
Science & Research
Overview of more VideoLinks >>>