Breakthrough in the treatment of bacterial meningitis

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It can take just hours after the symptoms appear for someone to die from bacterial meningitis. Now, after years of research, experts at The University of Nottingham have finally discovered how the deadly meningococcal bacteria is able to break through the body's natural defence mechanism and attack the brain.

The discovery could lead to better treatment and vaccines for meningitis and could save the lives of hundreds of children.
Bacterial meningitis in childhood is almost exclusively caused by the respiratory tract pathogens Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae. The mechanism used by these lethal germs to break through the blood brain barrier (BBB) has, until now, been unknown.
The team led by Dlawer Ala'Aldeen, Professor of Clinical Microbiology and Head of the Molecular Bacteriology and Immunology Group at the Centre for Biomolecular Sciences, recently discovered that all three pathogens target the same receptor on human cerebrovascular endothelial cells — the specialised filtering system that protects our brain from disease — enabling the organisms to cross the blood-brain barrier.
Their findings, published today in The Journal of Clinical Investigation, suggest that disruption or modulation of this interaction of bacterial adhesins with the receptor might offer unexpectedly broad protection against bacterial meningitis and may provide a therapeutic target for the prevention and treatment of disease.
Professor Ala'Aldeen, who has been studying meningitis and its causes for over 20 years, said: "This is a significant breakthrough which will help us design novel strategies for the prevention and treatment of bacterial meningitis. Identification of the human receptor and bacterial ligands is like identifying a mysterious key and its lock, which will open new doors and pave the way for new discoveries."
The research, carried out in collaboration with the Department of Infectious Diseases at St. Jude Children's Research Hospital in Memphis Tennessee, also involved students from the University who have been regular and willing volunteers in the research programme.
Professor Ala'Aldeen said: "The ultimate aim is to save lives by protecting the healthy and curing the sick. We are one step closer to new breakthroughs that would prevent disease or its complications. There still is a long way to go before we have the ultimate vaccine and the ultimate treatment of bacterial meningitis."
Source: University of Nottingham (news : web)

Biotechnology: Engineered Moss Can Produce Human Proteins

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ScienceDaily (May 11, 2009) — ETH Zurich researchers have shown that mosses and humans share unexpected common characteristics. These evolutionary relics could be useful in the production of therapeutic proteins.

At first glance, mosses and human beings have little in common. The moss Physcomitrella patens is small, pale green, immobile, and uses sunlight as its energy source. Humans are large, mobile, and need to obtain energy by eating vegetable or animal foods.
Transferring mammalian genes into moss
This made the result of the experiments carried out by researchers in the group led by Martin Fussenegger, Professor of Chemical and Bioengineering at ETH Zurich, all the more astonishing. In collaboration with researchers at the University of Freiburg im Breisgau, the PhD student Marc Gitzinger carried out tests to see what happens when unmodified human or mammalian genes are inserted into the moss genome. They transferred the foreign, unmodified genes into the moss and discovered that the moss was easily able to manufacture the proteins encoded therein.
This cannot be taken for granted, since the same process does not work when a mammalian gene is implanted into what are known as “higher” flowering plants. The reason is that sections of the start and finish sequences of the genes of animals, plants, fungi and bacteria are considerably different. They are responsible for ensuring that a gene in the organism is recognized as such, and the proteins encoded by it are produced in the correct amount and are released from the cell. The more remote the relationship between living organisms, the greater the difference between these sequences. This is why biotechnologists must normally adapt them to a foreign organism before transplanting a gene into it. The researchers were astonished to find that this was not necessary in the case of the moss.
Moss as a generalist
The explanation given for this by Ralf Reski, Professor of Plant Biotechnology at the University of Freiburg im Breisgau, is that the moss has remained a generalist. It underwent the last major modification about 450 million years ago when it changed from living in water to a life on land, adapting to the new living conditions and then remaining unaltered for millions of years, both in its appearance and at a genetic level.
The process used by the moss to produce its proteins is less sophisticated than in “higher” organisms. In contrast to the moss, these latter organisms underwent major further developments and specializations over the course of 450 million years. On the other hand, the moss clearly retained – for millions of years – the ability to read foreign genes such as those from mammals and thus also from humans, and to translate them into proteins, probably without ever having made any use of this capability during these 450 million years.
A cost-effective alternative to mammalian cells
Today, the moss Physcomitrella patens and its ability to manufacture mammalian proteins could help to satisfy the large worldwide demand for therapeutic proteins. One well-known example is insulin, which enables diabetics to control their blood sugar level.
Nowadays, therapeutic proteins are mainly manufactured in mammalian cells, which are very expensive to culture. They need to be maintained at body temperature with a continuous supply of nutrients and oxygen, and the production process is costly. At present, global production capacity cannot match the demand. Because of the difficulties involved in handling them, production is possible only in industrialized countries.
In contrast, the moss Physcomitrella patens is comparatively undemanding. It needs water, a couple of nutrient salts and some light to allow it to flourish and produce proteins. This makes it convenient and simple to handle in a bioreactor, and, in the future, it might enable even less developed nations to satisfy their requirement for therapeutic proteins. However, further research will be needed before the moss can be used to produce therapeutic proteins on an industrial scale.
Journal reference:
Gitzinger et al. Functional cross-kingdom conservation of mammalian and moss (Physcomitrella patens) transcription, translation and secretion machineries. Plant Biotechnology Journal, 2009; 7 (1): 73 DOI: 10.1111/j.1467-7652.2008.00376.x
Adapted from materials provided by ETH Zurich.

Beyond A 'Speed Limit' On Mutations, Species Risk Extinction

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http://www.sciencedaily.com/releases/2007/10/071001172753.htm

Science Daily — Harvard University scientists have identified a virtual "speed limit" on the rate of molecular evolution in organisms, and the magic number appears to be 6 mutations per genome per generation -- a level beyond which species run the strong risk of extinction as their genomes lose stability.
By modeling the stability of proteins required for an organism's survival, Eugene Shakhnovich and his colleagues have discovered this essential thermodynamic limit on a species's rate of evolution. Their discovery, published recently in the Proceedings of the National Academy of Sciences, draws a crucial connection between the physical properties of genetic material and the survival fitness of an entire organism.
"While mathematical genetics research has brought about some remarkable discoveries over the years, these approaches always failed to connect the dots between the reproductive fitness of organisms and the molecular properties of the proteins encoded by their genomes," says Shakhnovich, professor of chemistry and chemical biology in Harvard's Faculty of Arts and Sciences. "We've made an important step toward finally bridging the gap between macroscopic and microscopic biology."
According to Shakhnovich, crucial aspects of an organism's evolutionary fitness can be directly inferred by inspecting its DNA sequences and analyzing how the proteins encoded by those sequences fold. DNA sequences encode the order of amino acids in a protein, and amino acids act as the protein's basic building blocks by arranging themselves into a structure that allows the protein to perform its biological function.
The research was inspired in part by the longstanding recognition that knocking out essential genes, making them inactive, produces a lethal phenotype, or a physiologically unviable organism.
"From there, we made the simple assumption that in order for an organism to be viable, all of its essential genes -- those that support basic cell operations -- have to encode at least minimally stable proteins," says Shakhnovich. "What occurs over the long process of evolution is that random mutations can either encode slightly more or less stable proteins."
If enough mutations push an essential protein towards an unstable, non-functional structure, the organism will die. Shakhnovich's group found that for most organisms, including viruses and bacteria, an organism's rate of genome mutation must stay below 6 mutations per genome per generation to prevent the accumulation of too many potentially lethal changes in genetic material.
The existence of a mutation limit for viruses helps explain how the immune system can perform its function. Because viral replication and survival can only occur at a limited rate, the body has a window of time to develop antibodies against infectious agents. Furthermore, if the mutation rate is high, the size of the genome in question must be small to stay within the bounds of the speed limit -- thus organisms that tend to mutate quickly are those with concise genomes, such as viruses and bacteria.
The Shakhnovich speed limit also offers an explanation for observed differences in genome sizes between organisms with genome error correction -- such as bacteria, mammals, birds, and reptiles -- and those without, such as RNA viruses: In more complex organisms, cells have evolved correction systems to detect and fix errors in DNA replication. These systems drastically reduce the number of mutations per replication, increasing the mutational stability of the genome and allowing more intricate and delicate biological systems to develop without the risk of interruptive mutations.
"It's an interesting corollary because it suggests that there is a fundamental tradeoff between evolutionary security and adaptive flexibility: Larger, more complex organisms have to have error correction to protect organismic viability, but this means the rate of evolution slows down significantly," Shakhnovich says. "As organisms become more complex, they have more to lose and can't be as radically experimental with their genomes as some viruses and bacteria."
Co-authors on the paper are Konstantin B. Zeldovich of the Department of Chemistry and Chemical Biology and Peiqiu Chen of the departments of Physics and of Chemical and Chemical Biology in Harvard's Faculty of Arts and Sciences. Their work is funded by the National Institutes of Health.
Note: This story has been adapted from material provided by Harvard University.

Fausto Intilla
www.oloscience.com

Indian Bug Is The Ancestor Of Crohn's Disease Pathogen

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http://www.sciencedaily.com/releases/2007/10/071002213435.htm

Science Daily — An Indian team of researchers led by Seyed E. Hasnain of the Institute of Life Sciences (ILS), University of Hyderabad, India has found that a seemingly unknown mycobacterial organism Mycobacterium indicus pranii (MIP) could be the earliest ancestor of the 'generalist' branch of mycobacterial pathogens.
The 'generalist' bacteria infect anything from cockroaches to human and are capable of surviving in soil and water as against human adapted 'specialists' such as tubercle and leprosy bacilli. TB, a disease that killed about 1.7 million humans last year alone, is caused by a member of the Mycobacterial family of pathogens.
The finding further suggests that the prominent 'generalist' pathogen M. avium which seriously haunts AIDS patients, together with its close associate M. avium paratuberculosis (MAP), the agent of Crohn's disease in humans and Johne's disease in cattle descended from the MIP. It was also found that the MIP and the MAP bacilli initially inhabited water bodies and infected marine organisms predated by fishes finally arriving on soil through bird-droppings.
The MIP bacilli, also called as Mycobacterium w (Mw) were first isolated in India by G. P. Talwar at the All India Institute of Medical Sciences, New Delhi, in eighties and it is currently used, after an extensive and perhaps the largest clinical trial in the world, as an immunotherapeutic against leprosy in India.
The success with MIP based leprosy vaccine has led to human clinical evaluations of MIP in interventions against HIV-AIDS, psoriasis and bladder cancer in India. MIP, commercially available as 'Immuvac', is currently the focus of advanced multi-centric phase III clinical trials for its antituberculosis efficacy.
The comparative genomics study based on complete sequence of the MIP organism published in PLoS One reports observations based on the first ever whole genome sequencing project from India, carried out jointly by the ILS, the Centre for DNA fingerprinting and Diagnostics also at Hyderabad and the University of Delhi.
The study provides an important evolutionary basis for the acquisition and optimization of virulence in mycobacteria and determinants of boundaries therein. Similarly these efforts constitute a step forward in understanding the role of non-pathogenic and saprophytic mycobacteria in immunomodulation and in triggering innate immune responses. The study advocates exploitation of genetic similarity between MIP and MAP as a plausible advantage for therapeutic intervention against Crohn's and Johne's diseases.
Citation: Ahmed N, Saini V, Raghuvanshi S, Khurana JP, Tyagi AK, et al (2007) Molecular Analysis of a Leprosy Immunotherapeutic Bacillus Provides Insights into Mycobacterium Evolution. PLoS ONE 2(10): e968. doi:10.1371/journal.pone.0000968
Note: This story has been adapted from material provided by Public Library of Science.

Fausto Intilla
www.oloscience.com

Battling Bacteria: Antimicrobial 'Hole Puncher' Mechanism Described

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http://www.sciencedaily.com/releases/2007/09/070920111411.htm

Science Daily — In the battle against bacteria, researchers have scored a direct hit. They have made a discovery that could shorten the road to new and more potent antibiotics.

The rapid development of bacterial resistance to conventional antibiotics (such as penicillin or vancomycin) has become a major public health concern. Because resistant strains of bacteria can arise faster than drug companies can create antibiotics, understanding how these molecules function could help companies narrow their focus on potential antibiotics and bring them to market sooner.
As reported in a paper accepted for publication in the Journal of the American Chemical Society and posted on its Web site, researchers have now deciphered the molecular mechanism behind selective antimicrobial activity for a prototypical class of synthetic compounds.
The compounds, which mimic antimicrobial peptides found in biological immune systems, "function as molecular 'hole punchers,' punching holes in the membranes of bacteria," said Gerard Wong, a professor of materials science and engineering, physics, and bioengineering at the U. of I., and a corresponding author of the paper. "It's a little like shooting them with a hail of nanometer-sized bullets -- the perforated membranes leak and the bacteria consequently die."
The researchers also determined why some compounds punch holes only in bacteria, while others kill everything within reach, including human cells.
"We can use this as a kind of Rosetta stone to decipher the mechanisms of much more complicated antimicrobial molecules," said Wong, who also is a researcher at the university's Beckman Institute.
"If we can understand the design rules of how these molecules work, then we can assemble an arsenal of killer molecules with small variations, and no longer worry about antimicrobial resistance."
In a collaboration between the U. of I. and the University of Massachusetts at Amherst, the researchers first synthesized a prototypical class of antimicrobial compounds, then used synchrotron small-angle X-ray scattering to examine the structures made by the synthetic compounds and cell membranes.
Composed of variously shaped lipids, including some that resemble traffic cones, the cell membrane regulates the passage of materials in and out of the cell. In the presence of the researchers' antimicrobial molecules, the cone-shaped lipids gather together and curl into barrel-shaped openings that puncture the membrane. Cell death soon follows.
The effectiveness of an antimicrobial molecule depends on both the concentration of cone-shaped lipids in the cell membrane, and on the shape of the antimicrobial molecule, Wong said. For example, by slightly changing their synthetic molecule's length, the researchers created antimicrobial molecules that would either kill nothing, kill only bacteria, or kill everything within reach.
"By understanding how these molecules kill bacteria, and how we can prevent them from harming human cells, we can provide a more direct and rational route for the design of future antibiotics," Wong said.
This work was supported by the National Science Foundation, the National Institutes of Health and the Office of Naval Research.
Note: This story has been adapted from a news release issued by University of Illinois at Urbana-Champaign.

Fausto Intilla

www.oloscience.com

Parasitic Battles Can Involve Gene Transfer That Aids Evolution

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http://www.sciencedaily.com/releases/2007/09/070905134534.htm

Science Daily — Scientists at MIT's Department of Civil and Environmental Engineering and the Technion Israel Institute of Technology have for the first time recorded the entire genomic expression of both a host bacterium and an infecting virus over the eight-hour course of infection.

The results of this research likely will encourage scientists in several fields to rethink their approach to the study of host-virus systems, which are believed to play a key evolutionary role by facilitating the transfer of genes between species.
Professors Debbie Lindell of the Technion and Sallie Chisholm of MIT and co-authors report in the Sept. 6 issue of Nature that their study of a system involving the marine bacteria, Prochlorococcus, leads them to speculate that viral infection may play a role in shaping the genetic repertoire of families of bacteria, even though individual infected bacteria die.
This could indicate that the meeting between a marine bacterial host and its virus may not be just a battle between two individuals, but an evolutionarily significant exchange that helps both species become more fit for life in the ocean environment.
"The current status of host-virus relations has been influenced by a rich history of interactions," said Lindell. "While we can't definitively pin down the sequence of past co-evolutionary events, our findings suggest a novel means through which the exchange of beneficial genes between host and virus have been triggered."
And, because the pattern of genomic expression in this host-virus system differed significantly from that in the more commonly studied system of intestinal bacteria such as E. coli and a virus called T7, the research will likely lead to increased appreciation for the need to study diverse types of marine bacteria, rather than relying on a single system as a broad model.
"We hope this work will encourage scientists to explore a wide range of host-pathogen systems and thus lead to a significant broadening of our understanding of the diversity of the host-pathogen interactions existing in nature," said Chisholm, one of the discoverers of Prochlo-rococcus in 1985. "More importantly, these studies will help us understand the role these interactions play in shaping microbial ecosystems."
Researchers have only in the past few decades begun discovering and studying ecologically relevant ocean bacteria, such as Prochlorococcus, which play a very important role in our lives. These single-celled photosynthetic bacteria use light energy to produce oxygen and organic carbon --supplying a significant portion of the oxygen we breathe--and forming the basis for the ocean food chain.
In previously studied host-virus systems, a virus hijacks the bacterial host cell and shuts down genome expression immediately, preventing the bacterium from conducting its own metabolic processes. The attacking virus redirects expression to its own genome and activates the genes beneficial for its activity, which is to replicate itself quickly at the cost of the host.
But uncharacteristically, in the system of Prochlorococcus and virus P-SSP7, an unprecedented 41 of the bacteria's 1,717 genes were upregulated. That is, the researchers detected increased quantities of the messenger RNA encoded by these genes in the cell during the infection process. The upregulation of so many host genes during infection is a phenomenon unseen before in the world of bacteriology.
Moreover, many of the host genes upregulated during infection are among those that are found in genomic islands in the host, variable regions that appear to be hot-spots for genetic exchange between bacterial hosts and viruses. In this case, some of the genes that have been transferred back and forth encode for proteins that affect the bacteria's ability to adapt to changes in environmental factors, such as nutrient deprivation and light stress. The scientists hypothesize that modifications made to the bacterial genes when they were in the virus led to new versions of the proteins that may provide the bacteria with an increased ability to withstand environmental changes. It is also possible that multiple copies of a gene provide some benefit.
Another unusual occurrence is that the viral genome contains genes transferred from bacterial hosts that encode energy-producing proteins, including photosynthesis genes that cyanobacteria need for metabolism and DNA replication. Although these genes are positioned far apart in the viral genome, they are transcribed at the same time during infection rather than in the usual left-to-right order. This leads the researchers to surmise that the virus is trying to keep its host alive longer so that the host continues to provide the energy needed for the virus's own DNA replication.
Lindell and Chisholm believe the most plausible scenario to explain the gene upregulation and gene trading is that the bacterium activates certain genes in response to infection as a means of self-protection. The virus has "learned" to use those genes to its own advantage and so incorporates them into its own genome. Later, when infecting another bacterium, the virus upregulates those genes itself to facilitate its own reproduction within the host bacterium. When a bacterium survives an infection, those viral modified genes are incorporated back into the bacterial DNA in genome islands, making that bacterium and its descendants more likely to survive in the harsh ocean environment.
"These viral parasites cooperate with their hosts during infection, providing proteins that probably function within host metabolic pathways, to squeeze every bit of energy out them before killing them off," said Lindell. "Yet on evolutionary scales, such host-pathogen interactions are influencing the evolution of gene content in both host and virus, which in turn is likely impacting their ability to colonize new niches."
Next steps in the research are to see if the host-like genes in the virus really do confer a fitness advantage to the virus and then to the host bacterium when transferred back.
Funding for this research came from the Department of Energy's GTL Program, the Gordon and Betty Moore Foundation, and the National Science Foundation.
Lindell performed the research as a postdoctoral associate in Chisholm's lab before joining the Technion faculty in the Department of Biology in October 2006. It builds on previous work in Chisholm's lab at MIT, including research by Lindell and co-author Matthew Sullivan, who in 2004 noted the presence of host genes in the viruses and their transfer back to the host, and by Maureen Coleman, who in 2006 found genomic islands in the host that had most likely come from viruses.
Other authors are MIT graduate students Gregory Kettler and Coleman; MIT postdoctoral associate Sullivan; Jacob Jaffe of the Broad Institute; Matthias Futschik and Ilka Axmann of Humboldt University; Trent Rector, Robert Steen and George Church of Harvard Medical School; and Wolfgang Hess of the University of Freiburg.
Note: This story has been adapted from a news release issued by Massachusetts Institute of Technology.

Fausto Intilla

www.oloscience.com