Crafty manipulator deceives cellular waste disposal system

This news release is available in German.
Viral infections always follow a similar course. The pathogen infiltrates the host cells and uses their replication and protein production machinery to multiply. The virus has to overcome the initial barrier by docking on the surface of the cell membrane. The cell engulfs the virus in a bubble and transports it towards the cell nucleus. During this journey, the solution inside the bubble becomes increasingly acidic. The acidic pH value is ultimately what causes the virus's outer shell to melt into the membrane of the bubble.
Capsid cracked open like a nut
However, this is only the first part of the process. Like other RNA viruses, the flu virus has to overcome a further obstacle before releasing its genetic code: the few pieces of RNA that make up the genome of the flu virus are packed into a capsid, which keeps the virus stable when moving from cell to cell. The capsid also protects the viral genes against degradation.
Until now, very little has been known about how the capsid of the flu virus is cracked open. A team of researchers from the ETH Zurich, the Friedrich Miescher Institute for Biomedical Research in Basel and the Biological Research Center in Szeged (Hungary) has now discovered exactly how this key aspect of flu infection works: the capsid of the influenza A virus imitates a bundle of protein waste – called an aggresome – that the cell must disentangle and dispose. Deceived in such a way, the cellular waste pickup and disposal complex cracks open the capsid. This discovery has recently been published in the journal Science.

The virus capsid carries cellular waste 'labels' on its surface. These waste labels, called unanchored ubiquitin, call into action an enzyme known as histone deacetylase (HDAC6), which binds to ubiquitin. At the same time, HDAC6 also binds to scaffolding motor proteins, pulling the perceived "garbage bundle" apart so that it can be degraded. This mechanical stress causes the capsid to tear, releasing the genetic material of the virus. The viral RNA molecules pass through the pores of the cell nucleus, again with the help of cellular transport factors. Once within the nucleus, the cell starts to reproduce the viral genome and build new virus proteins.
Tricking the waste pickup and disposal system
This finding came as a great surprise to the researchers. The waste disposal system of a cell is essential for eliminating protein garbage. If the cell fails to dispose of these waste proteins (caused by stress or heat) quickly enough, the waste starts to aggregate. To get rid of these aggregates, the cell activates its machinery, which dismantles the clumps and breaks them down into smaller pieces, so that they can be degraded. It is precisely this mechanism that the influenza virus exploits.
The researchers were also surprised by how long the opening of the capsid takes, with the process lasting around 20-30 minutes. The total infection period – from docking onto the cell's surface to the RNA entering the cell nucleus – is two hours. "The process is gradual and more complex than we thought," says Yohei Yamauchi, former postdoc with ETH professor Ari Helenius, who detected HDAC6 by screening human proteins for their involvement in viral infection. In a follow-up study, lead author Indranil Banerjee confirmed how the flu virus is programmed to trick HDAC6 into opening its capsid.
A mouse model provided encouraging proof. If the protein HDAC6 was absent, the flu infection was significantly weaker than in wild-type mice: the flu viruses did not have a central docking point for binding to the waste disposal system.
Stopping waste labels from binding
The researchers headed by Professor of Biochemistry, Ari Helenius have broken new ground with their study. Little research has previously been conducted on how an animal virus opens its capsid. This is one of the most important stages during infection, says the virologist. "We did, however, underestimate the complexity associated with unpacking the capsid," admits Helenius. Although he wrote a paper on the subject 20 years ago, he did not further pursue his research at that time. He attributes the current breakthrough to new systemic approaches to researching complex systems.
Whether there are therapeutic applications for the findings remains to be seen as an absence of HDAC6 merely moderates the infection rather than prevents it. The known HDAC6 inhibitors target its two active areas. Blocking the enzymatic activity does not help prevent HDAC6 from binding to ubiquitin, but rather supports the virus by stabilizing the cell's framework.
"We would need a substance that prevents HDAC6 from binding to ubiquitin, without touching the enzyme," says Yamauchi. Nevertheless, the structure of HDAC6 indicates that this is possible and follow-up experiments are already planned. The researchers have already filed a patent for this purpose.
Quick mutations
These new findings also underpin one of the main challenges of fighting viruses. Viruses make intelligent use of many processes that are essential for our cells. These processes cannot simply be "switched off", as the side effects would be severe. Furthermore, viruses mutate very quickly. In the case of the flu medicine Tamiflu, the influenza virus evaded it by a mutation that changed the target protein of the active substance on its surface, thereby rendering the drug useless.
It is possible that other viruses might use the waste processing system to decapsidate or uncoat their DNA or RNA and to infect cells efficiently. Helenius does not plan to conduct further research in this field, however, as ETH Zurich will dissolve the research group upon his retirement.


Banerjee I, Miyake Y, Nobs SP, Schneider C, Horvath P, Kopf M, Matthias P, Helenius A, Yamauchi Y. Influenza A virus uses the aggresome processing machinery for host cell entry.Science, published online 23rd October 2014. DOI: 10.1126/science.1257037
Antibiotic-resistant bacteria can share resources to cause chronic infections, Vanderbilt University investigators have discovered. Like the individual members of a gang who might be relatively harmless alone, they turn deadly when they get together with their "friends."
The findings, reported Oct. 8 in Cell Host & Microbe, shed light on a long-standing question in infectious diseases and may inform new treatment strategies, said Eric Skaar, Ph.D., MPH, Ernest W. Goodpasture Professor of Pathology, Microbiology and Immunology.
One way that Staphylococcus aureus and other pathogens can become resistant to antibiotics is by changing the way they generate energy and becoming "small colony variants," which are small and weak, Skaar explained.
"The question has been: how do bacteria that are less fit and grow poorly in the laboratory cause such persistent infections in humans?"
The current studies support the notion that antibiotic-resistant staph bacteria, including methicillin-resistant (MRSA) strains, can exchange nutrients with each other and even with other bacterial species, including the "normal" microbes of the microbiome, to increase their virulence during an infection.
The findings challenge infectious disease dogma, Skaar said.
"The thinking has been that if an infection becomes resistant to antibiotics, then the resistant organisms appeared clonally, meaning they're all genetically the same."
Skaar and his colleagues wondered if perhaps instead "there are a bunch of organisms that became resistant in different ways and that can exchange the molecules they're each individually missing."
Two fellows in the lab, Neal Hammer, Ph.D., and James Cassat, M.D., Ph.D., now an assistant professor of Pediatrics at Vanderbilt, tested this hypothesis by mixing together two different small colony variant strains of staph – one that can't produce heme and the other that can't make menaquinone. They found that in culture, these strains exchanged the two metabolites and grew as if they were wild-type staph.

The investigators demonstrated that either staph strain alone (heme- or menaquinone-deficient) caused only minimal bone infection, but mixed together, they caused a fully virulent and bone-destroying infection.Next, they tested the idea in a mouse model of bone infection (osteomyelitis). Antibiotic-resistant small colony variant S. aureus is the cause of chronic and difficult to treat osteomyelitis and also of lung infections in patients with cystic fibrosis (CF).
"In bone, these bacteria are trading molecules," Skaar said.
In collaboration with C. Buddy Creech, M.D., MPH, associate professor of Pediatrics, the researchers isolated samples of staph small colony variants and normal bacteria from the lungs of CF patients.
When individual CF staph small colony variants were mixed together in culture, they grew like wild-type bacteria. Likewise, co-culture of CF staph small colony variants with normal microbiome bacterial species also enhanced the growth of staph in culture.
"The microbiome of a cystic fibrosis patient's lungs can provide nutrients to these small colony variants and revert them to wild-type behavior," Skaar said.
"Our findings show that these antibiotic-resistant infections are not what we thought they were – they're not a single strain of bacteria with a single lesion leading to the small colony variant phenotype," he said. "Instead, they're a mixed population of organisms that are sharing nutrients.
"They act like a big group of bullies until you hit them with drugs, then they stop sharing resources and are resistant. When the drugs go away, they start sharing resources again and get even tougher.
"We're now a little bit smarter about how these organisms are behaving in an infection, which I think we can use to inform new treatment approaches."
Preventing the nutrient exchange, for example, may offer a new therapeutic strategy against these antibiotic-resistant organisms, Skaar said.

Salk scientists identify a promising target for HIV/AIDS treatment

LA JOLLA–Like a slumbering dragon, HIV can lay dormant in a person’s cells for years, evading medical treatments only to wake up and strike at a later time, quickly replicating itself and destroying the immune system.
Scientists at the Salk Institute have uncovered a new protein that participates in active HIV replication, as detailed in the latest issue of Genes & Development. The new protein, called Ssu72, is part of a switch used to awaken HIV-1 (the most common type of HIV) from its slumber.
More than 35 million people worldwide are living with HIV and about a million people die a year due to the disease, according to the World Health Organization. There is no cure, and while regular medication makes the disease manageable, treatment can have severe side effects, is not readily available to everyone and requires a regiment that can be challenging for patients to adhere to.
The team began by identifying a list of 50 or so proteins that interact with a well-known protein HIV creates called Tat.
“The virus cannot live without Tat,” says Katherine Jones, Salk professor in the Regulatory Biology Laboratory and senior author of the study.
Tat acts as a lookout in the cell for the virus, telling the virus when the cellular environment is favorable for its replication. When the environment is right, Tat kicks off the virus’ transcription, the process by which HIV reads and replicates its building blocks (RNA) to spread throughout the body.
One of the proteins on the list that caught Jones’ eye was Ssu72 (a phosphatase). This enzyme had been shown in yeast to affect the transcription machinery. Sure enough, her team found that Ssu72 binds directly to Tat and not only begins the transcription process, but also creates a feedback loop to ramp up the process.
“Tat is like an engine for HIV replication and Ssu72 revs up the engine,” says Lirong Zhang, one of the first authors and a Salk researcher. “If we target this interaction between Ssu72 and Tat, we may be able to stop the replication of HIV.”
The findings were surprising to the team because Tat, a relatively small protein, was previously thought to have a simpler role. Jones' lab previously discovered the CycT1 protein, another critical protein that Tat uses to begin the steps of replicating the virus. “After all these years, we thought that Tat only had this one partner (CycT1), but when we looked at it a bit harder, we found that it also binds and stimulates the Ssu72 phosphatase, which controls an immediately preceding step to switch on HIV,” she said.
From left: Katherine Jones, Yupeng Chen & Lirong Zhang
Click here for a high-resolution image.
Image: Courtesy of the Salk Institute for Biological Studies
CycT1 is needed for normal cell function, so it may not be an ideal anti-viral target. However, the team found that Ssu72 is not required for making RNA for most host cell genes in the way it is used by HIV, making it a potentially promising target for drug therapy.
“Many proteins that Tat interacts with are essential for normal cellular transcription so those can’t be targeted unless you want to kill normal cells,” says co-first author Yupeng Chen, a Salk researcher. “Ssu72 seems to be different–at least in the way it is used by HIV.”
Now that the team knows the protein is specifically required for HIV transcription, they next plan to investigate how they can target the protein, for example by inhibiting Ssu72’s ability kick off the transcription process. They are also examining whether latent HIV infections result from low levels of Ssu72 in resting T cells. And stay tuned: the lab is excited about checking other new host cell partners of Tat that were identified in this study.
Authors of the work include Katherine A. Jones, Yupeng Chen, Lirong Zhang, Conchi Estar, Seung H. Choi, Luis Moreno Jr. of the Salk Institute; John R. Yates III and James J. Moresco of The Scripps Research Institute; and Jonathan Karn of Case Western Reserve University School of Medicine.
Funding for the work was provided by the National Institutes of Health, the National Center for Research Resources, the Blasker-Rose-Miah Fund and the Margaret T. Morris Foundation.
About the Salk Institute for Biological Studies:
The Salk Institute for Biological Studies is one of the world's preeminent basic research institutions, where internationally renowned faculty probes fundamental life science questions in a unique, collaborative, and creative environment. Focused both on discovery and on mentoring future generations of researchers, Salk scientists make groundbreaking contributions to our understanding of cancer, aging, Alzheimer's, diabetes and infectious diseases by studying neuroscience, genetics, cell and plant biology, and related disciplines.
Faculty achievements have been recognized with numerous honors, including Nobel Prizes and memberships in the National Academy of Sciences. Founded in 1960 by polio vaccine pioneer Jonas Salk, MD, the Institute is an independent nonprofit organization and architectural landmark.
Many different microbes can cause pneumonia, and treatment may be delayed or off target if doctors cannot tell which bug is the culprit. A novel approach—analyzing a patient's breath for key chemical compounds made by the infecting microbe—may help detect invasive aspergillosis, a fungal infection that is a leading cause of mortality in patients with compromised immune systems, according to a proof-of-concept study now online in Clinical Infectious Diseases.

Currently difficult to diagnose, this type of fungal pneumonia often requires a lung biopsy for definitive identification. For debilitated patients with weakened immune systems, including organ or bone marrow transplant recipients and patients on chemotherapy, such an invasive procedure may be challenging. A non-invasive method that can also identify the type of fungus causing pneumonia could lead to earlier and more targeted treatment in these cases.
Sophia Koo, MD, of Brigham and Women's Hospital in Boston, and a team of researchers wondered if they could find a unique "chemical signature" in the breath of patients being evaluated for fungal pneumonia. In the lab, they identified several compounds, or metabolites, normally produced by Aspergillus fumigatus and other fungi that can cause pneumonia.
The researchers then analyzed breath samples from 64 patients with suspected cases of invasive aspergillosis and assessed whether it was possible to distinguish patients with this fungal pneumonia from patients who did not have this illness. Based on the identification of these fungal compounds in the breath samples, they identified patients with the fungal infection with high accuracy—94 percent sensitivity and 93 percent specificity. (In other words, the method was able to detect 94 percent of patients who actually had or likely had the disease, and misidentified as infected 7 percent of patients who were not actually infected.)
There were no adverse events related to the breath collection procedure, the authors reported. It was well-tolerated, including by patients who had difficulty breathing or required supplemental oxygen.
"Identification of the underlying microbial etiology remains elusive in most patients with pneumonia, even with invasive diagnostic measures," Dr. Koo said. "Our findings provide proof-of-concept that we can harness detection of species-specific metabolites to identify the precise microbial cause of pneumonia, which may guide appropriate treatment of these infections."
More research will be needed to validate the findings and refine the approach before it can be considered for clinical use, the authors noted. If supported by future research, the method also may have applications in other kinds of pneumonia. "We can likely also use this volatile metabolite profiling approach to identify other, more common causes of pneumonia," Dr. Koo said.
Fast Facts:
  • Invasive aspergillosis is a cause of fungal pneumonia that is difficult to diagnose, and it is a leading cause of mortality in immune-compromised patients.
  • Researchers were able to detect key compounds, or metabolites, produced by Aspergillus fungi in the breath of patients with fungal pneumonia.
  • Using this approach, researchers correctly distinguished patients with invasive aspergillosis from those who did not have the illness.

Clinical Infectious Diseases is a leading journal in the field of infectious disease with a broad international readership. The journal publishes articles on a variety of subjects of interest to practitioners and researchers. Topics range from clinical descriptions of infections, public health, microbiology, and immunology to the prevention of infection, the evaluation of current and novel treatments, and the promotion of optimal practices for diagnosis and treatment. The journal publishes original research, editorial commentaries, review articles, and practice guidelines and is among the most highly cited journals in the field of infectious diseases. Clinical Infectious Diseases is an official publication of the Infectious Diseases Society of America (IDSA). Based in Arlington, Va., IDSA is a professional society representing nearly 10,000 physicians and scientists who specialize in infectious diseases. For more information, visit Follow IDSA on Facebook and Twitter.

A new report from the World Health Organization finds that tuberculosis has infected hundreds of thousands more people around the world than was estimated a year ago.

Tuberculosis (TB) is causing more infections and deaths the world over than previous estimates indicated, according to a new survey released by the World Health Organization (WHO) today (October 22). The WHO’s “Global Tuberculosis Report 2014” stated that in 2013 there were 9 million new cases of TB reported in the more than 200 countries that account for more than 99 percent of the world’s TB cases.
The number of reported cases this year is 400,000 more than the WHO estimated in last year’s report, but the increased numbers may indicate improvements in diagnosis and data reporting as well as unchecked spread of the disease. “There has been some real progress, particularly in Asia, but the overall situation remains catastrophic,” Richard Chaisson, director of the Johns Hopkins Center for Tuberculosis Research in Baltimore, Maryland, told ScienceInsider. “Improvements in some countries are offset by disastrous situations in others, with MDR [multidrug-resistant] TB, HIV-related TB, and continued high rates of missed diagnoses and deaths. The situation in Africa is particularly horrific, with TB killing more young people than any other cause.”
TB kills hundreds of thousands of people every year—an estimated 1.5 million people died from the disease in 2013, according to the WHO report—second only to HIV among infectious diseases.
Some infectious disease activists are criticizing the WHO report for being overly optimistic. “On the HIV side, we're doing stuff almost twice as fast in [reducing] deaths and multiple times as fast in incidence, even though TB is curable and HIV is not,” Mark Harrington, executive director of the New York City–based Treatment Action Group, which lobbies for stronger efforts to address both HIV and TB, told ScienceInsider.
Vanderbilt University researchers have partnered with Mapp Biopharmaceutical Inc. to develop new human antibody therapies for people exposed to the deadly Ebola and Marburg viruses.
James Crowe Jr., M.D., right, looks on as graduate student Andrew Flyak adjusts equipment in the Vanderbilt Vaccine Center used in the production of anti-Ebola antibodies.
Credit: Photo courtesy of Vanderbilt University

The San Diego-based company has developed an experimental treatment, called ZMapp, which contains antibodies manufactured in plants. ZMapp has prevented lethal disease in rhesus monkeys but has not yet been tested for safety and efficacy in humans.
At Vanderbilt, researchers are using a high-efficiency method to isolate and generate large quantities of human antibodies from the blood of people who have survived Ebola and Marburg infections and who are now healthy. No live virus is used in the research here.
The goal of the collaboration is to develop safe and effective antibody therapies that can provide short-term protection to health care workers and others at risk of exposure to the two hemorrhagic filoviruses, which kill in part by causing massive bleeding.
"Our laboratory has been isolating antibodies to major human pathogens such as Ebola in order to understand the basic science of immunity in humans," said lead Vanderbilt researcher James Crowe Jr., M.D., Ann Scott Carrell Professor and director of the Vanderbilt Vaccine Center.
"However, with the current urgent medical need for treatments for Ebola infection, we are thrilled to be working with Mapp Biopharmaceutical to produce the antibodies we have discovered as antiviral drugs that may benefit patients and health care workers facing this terrible epidemic," Crowe said.
The current Ebola outbreak, which began in West Africa last December, has killed more than 2,500 people, making it the deadliest outbreak since the virus was discovered in 1976. Health officials say the true death toll may be three or four times greater.
"Dr. James Crowe's success at isolating potent and effective human monoclonal antibodies against a wide range of infectious diseases is well recognized," said company president Larry Zeitlin, Ph.D. "Mapp Biopharmaceutical is delighted to collaborate with him to develop human therapeutics against a range of public health threats."
Monoclonal antibodies are made from a single clone of B cells, a type of white blood cell, that have been fused to myeloma (cancer) cells to form fast-growing "hybridomas." This allows researchers to quickly generate large quantities of antibodies against specific viral targets.
"We're the only lab in the world that has a high-efficiency human hybridoma technique for isolating human monoclonal antibodies," Crowe said.
The method, developed over the last 15 years, was instrumental in isolating antibodies from the blood of people who survived the worldwide 1918 influenza pandemic as well as antibodies to avian influenza, dengue and other current viral threats.
Crowe said his 12-person team is currently studying antibody responses to about 30 different viruses. "We're also working with Vanderbilt collaborators on bacteria -- Staph and Clostridium difficile ("C. diff") infection, a leading cause of hospital-associated diarrhea," he said.
Story Source:
The above story is based on materials provided by Vanderbilt University Medical Center. The original article was written by Bill Snyder. Note: Materials may be edited for content and length.
Frequent airplane travel may contribute to obesity by throwing off circadian rhythms and changing the composition of the intestinal microbiome, according to a new study.

Jet lag may be as disorienting to the microbes that inhabit the human intestinal tract as it is to the human, according to a new study of how disturbances to the circadian clock can impact the gut microbiome. Researchers in Israel have shown, in both mice and humans, that the bacterial assemblages inhabiting the digestive tract are vulnerable to the ravages of circadian rhythm alterations. And when the gut microbiome is disrupted, they found, a suite of maladies, including glucose intolerance and obesity, result.
Immunologist Eran Elinav of the Weizmann Institute of Science in Rehovot led a team of researchers that subjected mice to a disruption in their sleep cycle that mimicked jet lag from an 8-hour time difference in humans and surveyed changes to their gut microbes. The researchers, who published their work in Cell on Wednesday (October 15), also studied the microbiota of two people who flew from the U.S. to Israel, and found similar compositional and functional changes. “We saw that in the presence of jet lag, their microbes were completely messed up,” Elinav told Time.
When Elinav and his colleagues transferred jet-lagged microbes from either mice or humans into germ-free mice, the rodents became more susceptible to glucose intolerance and diabetes. “We could very nicely see that transferring the gut microbes from the point where jet lag was at its highest induced much more obesity and glucose intolerance,” he said.
The human microbiomes that changed in response to jet lag did, however, return to normal two weeks after their flight. But frequent air travel or other activities that disrupt sleep/wake cycles, such as shift work, could make the disruptions, and their resultant health problems, chronic.

Scientists have discovered that eating a traditional Japanese pickle could have “protective effects” in preventing people from catching the flu.

Human trials have been started after a study in mice showed the bacterium in suguki, a pickled turnip dish popular in Japan, reduced the likelihood the animals would contract illness.
According to the findings, which have been published in the journal Letters in Applied Microbiology, the Lactobacillus brevis bacteria led to increased production of disease-fighting antibodies – including flu-specific ones.
The impact in mice was strong enough to prevent infection from the H1N1 flu strain.
Researchers said a new study was now under way, in which they are giving people a probiotic drink containing the same KB290 strain of the bacterium found in suguki.
Study author Naoko Waki, from the Japanese food company Kagome, said: “Our results show that when a particular strain of Lactobacillus brevis is eaten by mice, it has protective effects against influenza virus infection.”
A protective layer of sugars called exopolysaccharides that protects the bacteria against acid stomach juices could lie behind its powers, the Japanese researchers believe.
“We know that exopolysaccharides have immune boosting effects in other similar bacteria, so we wonder if the exopolysaccharides of KB290 are responsible for the effects we see,” said Ms Waki.
While the research seems promising, the NHS advises that the best way to prevent colds and flu is still to live a healthy lifestyle with regular exercise, and to get vaccinations if possible. They say that flu jabs are the best bet for avoiding flu, and advise that there are no definitive studies to prove food supplements such as vitamin C, zinc or echinacea can stave off a cold.
Combining a PET scanner with a new chemical tracer that selectively tags specific types of bacteria, Johns Hopkins researchers working with mice report they have devised a way to detect and monitor in real time infections with a class of dangerous Gram-negative bacteria. These increasingly drug-resistant bacteria are responsible for a range of diseases, including fatal pneumonias and various bloodstream or solid-organ infections acquired in and outside the hospital.

"What we have produced is essentially a system that localizes the epicenter of infection and provides real-time tracking of bacterial activity, giving us rapid feedback on how the bacteria respond to antibiotics," says principal investigator Sanjay Jain, M.D., an infectious disease specialist at the Johns Hopkins Children's Center and director of the Center for Inflammation Imaging and Research at Johns Hopkins.
Describing their work in the Oct. 22 issue of the journalScience Translational Medicine, the team says the simplicity, speed and accuracy of the imaging model could change the way dangerous bacterial infections are diagnosed, monitored and treated. Although the work was conducted in mice, the researchers say clinical application in humans could happen quickly, because the system capitalizes on already available imaging devices -- PET scans -- and materials.
"Our approach could quickly and reliably detect infections caused by certain Gram-negative organisms and could speed up diagnosis and treatment by eliminating days-long waits for lab test results," says study co-author Edward Weinstein, M.D., Ph.D., an infectious disease specialist at the Johns Hopkins University School of Medicine. "Perhaps more importantly, the technique can give us critical insights into the basic mechanisms of disease and can help us evaluate the effect of drug therapy quickly."
The new technique, the researchers say, is superior to current imaging tools because it selectively precision-targets a common class of Gram-negative bacteria known as Enterobacteriaceae that includes notoriously virulent germs such as E. coli, Salmonella, Klebsiella, and dozens of other pathogens that can be particularly dangerous in hospitalized people. Some of the germs in the class, the research team notes, could also be used as biological weapons.
Current imaging tools, such as CT, MRI and PET scans, use inflammation as a surrogate to diagnose and monitor infection, the researchers say. Yet inflammation, which is the body's response to infection rather than infection itself, is not specific to bacteria and cannot distinguish true infections from non-infectious inflammation such as inflammation caused by cancer.
The new model emerged from a creative combination of existing PET scan technology -- a sophisticated 3-D visualization system for tumor imaging -- with an ingredient commonly used in sugar-free foods known as sorbitol. The model capitalizes on Gram-negative bacteria's fondness for sorbitol, which they readily soak up. By contrast, other classes of bacteria and other microorganisms, cancer, and human cells do not absorb sorbitol. The researchers hypothesized that converting an already available PET imaging tracer into radio-labeled sorbitol would selectively tag and light up clusters of Gram-negative bacteria inside the body. It did.
When researchers injected mice with the Gram-negative bacterium E. coli in one thigh and harmless dead bacteria in the other thigh, both injections produced inflammation. However, only the cluster of live E. coli attracted the radio tracer and lit up the screen -- a critical feature that let the researchers distinguish the actual bacterial infection from noninfectious inflammation. When the researchers injected one thigh with Gram-negative E. coli and the other thigh with the Gram-positive bacterium Staphyloccocus aureus, the radio tracer lit up only the thigh infected by the Gram-negative organism. In other words, the sorbitol-containing tracer differentiated between bacterial and sterile inflammation, as well as between infections caused by different classes of bacteria. Next, the researchers compared how their modified tracer fared in distinguishing brain inflammation caused by E. coli from cancer-induced brain inflammation. The tracer reliably and predictably lit up E. coli hot spots in the brain but not brain tumor cells.
When serious drug-resistant infections are suspected, the researchers explain, patients are routinely given broad-spectrum antibiotics while waiting -- often for days -- for lab tests to determine the specific organism responsible for the infection and which drugs should be used. Broad-spectrum antibiotics treat many bacteria at once, but their frequent and indiscriminate use has fueled drug resistance in recent years, making many pathogens impervious to common antibiotics.
"Using broad-spectrum antibiotics is not unlike firing a cannonball to kill a fly," says study co-author Alvaro Ordonez, M.D., a fellow in pediatric infectious diseases at the Johns Hopkins University School of Medicine. "While such treatment is clinically justified in patients with serious infections of unknown origin, it promotes bacterial resistance, so the long-term price that both patients and clinicians pay is rather steep."
Knowing quickly which organism is causing a patient's infection and which antibiotic can kill the bacteria could seriously lower that cost, Ordonez adds. This is where the new imaging system could play a critical role. In a separate set of experiments, the investigators showed that their imaging system rapidly captured how bacteria respond to drug treatment in real time. Targeted with the right antibiotic, the dying bacteria produced a visibly and progressively weaker image. By contrast, when bacteria failed to respond to an antibiotic, the strength of the signal remained as intense as ever, heralding treatment failure. Receiving such rapid feedback within hours instead of days could have profound effects on treatment decisions.
"Earlier identification of bacterial drug sensitivity could not only get patients on the mend sooner by giving them the right antibiotic, but in the long run it could save the U.S. health care system billions of dollars in unnecessary drug treatment," Jain says.
Story Source:
The above story is based on materials provided by Johns Hopkins MedicineNote: Materials may be edited for content and length.

Journal Reference:
  1. Edward A. Weinstein, Alvaro A. Ordonez, Vincent P. Demarco, Allison M. Murawski, Supriya Pokkali, Elizabeth M. Macdonald, Mariah Klunk, Ronnie C. Mease, Martin G. Pomper, and Sanjay K. Jain. Imaging Enterobacteriaceae infection in vivo with 18F-fluorodeoxysorbitol positron emission tomographyScience Translational Medicine, October 2014 DOI:10.1126/scitranslmed.3009815
A new study is helping to rewrite Ebola's family history. The research shows that filoviruses -- a family to which Ebola and its similarly lethal relative, Marburg, belong -- are at least 16-23 million years old.
Colorized transmission electron micrograph (TEM) of the Ebola virus.
Credit: Frederick A. Murphy, via the Centers for Disease Control and Prevention

Filoviruses likely existed in the Miocene Epoch, and at that time, the evolutionary lines leading to Ebola and Marburg had already diverged, the study concludes.
The research was published in the journal PeerJ in September. It adds to scientists' developing knowledge about known filoviruses, which experts once believed came into being some 10,000 years ago, coinciding with the rise of agriculture. The new study pushes back the family's age to the time when great apes arose.
"Filoviruses are far more ancient than previously thought," says lead researcher Derek Taylor, PhD, a University at Buffalo professor of biological sciences. "These things have been interacting with mammals for a long time, several million years."
According to the PeerJ article, knowing more about Ebola and Marburg's comparative evolution could "affect design of vaccines and programs that identify emerging pathogens."
The research does not address the age of the modern-day Ebolavirus. Instead, it shows that Ebola and Marburg are each members of ancient evolutionary lines, and that these two viruses last shared a common ancestor sometime prior to 16-23 million years ago.
Clues in 'fossil genes'
Taylor and co-author Jeremy Bruenn, UB professor of biological sciences, research viral "fossil genes" -- chunks of genetic material that animals and other organisms acquire from viruses during infection.
In the new study, the authors report finding remnants of filovirus-like genes in various rodents. One fossil gene, called VP35, appeared in the same spot in the genomes of four different rodent species: two hamsters and two voles. This meant the material was likely acquired in or before the Miocene Epoch, prior to when these rodents evolved into distinct species some 16-23 million years ago.
In other words: It appears that the known filovirus family is at least as old as the common ancestor of hamsters and voles.
"These rodents have billions of base pairs in their genomes, so the odds of a viral gene inserting itself at the same position in different species at different times are very small," Taylor says. "It's likely that the insertion was present in the common ancestor of these rodents."
The genetic material in the VP35 fossil was more closely related to Ebola than to Marburg, indicating that the lines leading to these viruses had already begun diverging from each other in the Miocene.
The new study builds on Taylor's previous work with Bruenn and other biologists, which used viral fossil genes to estimate that the entire family of filoviruses was more than 10 million years old. However, those studies used fossil genes only distantly related to Ebola and Marburg, which prevented the researchers from drawing conclusions about the age of these two viral lines.
The current PeerJ publication fills this viral "fossil gap," enabling the scientists to explore Ebola's historical relationship with Marburg.
Possible relevance to disease prevention
The first Ebola outbreak in humans occurred in 1976, and scientists still know little about the virus' history. The same dearth of information applies to Marburg, which was recognized in humans in 1967 and implicated in the death of a Ugandan health worker this month.
Understanding the virus' ancient past could aid in disease prevention, Taylor says. He notes that if a researcher were trying to create a single vaccine effective against both Ebola and Marburg, it could be helpful to know that their evolutionary lineages diverged so long ago.
Knowing more about filoviruses in general could provide insight into which host species might serve as "reservoirs" that harbor undiscovered pathogens related to Ebola and Marburg, Taylor says.
"When they first started looking for reservoirs for Ebola, they were crashing through the rainforest, looking at everything -- mammals, insects, other organisms," Taylor says. "The more we know about the evolution of filovirus-host interactions, the more we can learn about who the players might be in the system."
Taylor and Bruenn's co-authors on the PeerJ study include UB students Matthew Ballinger, Laura Hanzly and Jack Zhan, all in the UB Department of Biological Sciences.
Story Source:
The above story is based on materials provided by University at Buffalo. The original article was written by Charlotte Hsu. Note: Materials may be edited for content and length.

Journal Reference:
  1. Derek J. Taylor, Matthew J. Ballinger, Jack J. Zhan, Laura E. Hanzly, Jeremy A. Bruenn. Evidence that ebolaviruses and cuevaviruses have been diverging from marburgviruses since the MiocenePeerJ, 2014; 2: e556 DOI:10.7717/peerj.556
Norovirus is the most common cause of gastroenteritis in the UK. For most people, infection causes an unpleasant but relatively short-lived case of vomiting and diarrhea, but chronic infection can cause major health problems for people with compromised immune systems. In many cases, patients who have weaker immune systems suffer from norovirus infection for months to years, with some patients experiencing gastroenteritis for as many as eight years. Outbreaks can cause significant economic losses -- in UK hospitals alone, the cost of treating outbreaks is estimated at over £100 million a year, and foodborne outbreaks in the US lead to economic losses of around $2 billion per year.

The virus is notoriously difficult to study because it will not grow efficiently in the laboratory, therefore scientists often use a mouse norovirus to identify drugs that can inhibit infection. It is one of a class of viruses known as RNA viruses, which have ribonucleic acid (RNA) as their genetic material. Most of the major viruses that have the potential to become epidemics are of this class. RNA viruses replicate and mutate rapidly, making them challenging to develop vaccines or immunity against.
In a study published in the journal eLife and funded by the Wellcome Trust, a team of researchers led by Professor Ian Goodfellow has shown in mice with a long-term norovirus infection that the experimental drug favipiravir is effective at lowering levels of norovirus in the body, including in both tissue and faeces, which may help in reducing the severity of the disease and onward transmission.
Favipiravir is an experiment antiviral drug which is thought to be effective against a number of RNA viruses such as influenza, West Nile virus, yellow fever virus, and foot-and-mouth disease virus. It is currently also been tested as a potential drug to treat Ebola virus. The University of Cambridge team has shown that the drug works by causing the virus to self-destruct in a process known as 'lethal mutagenesis', which causes errors in the virus's genetic information; because RNA viruses replicate and mutate rapidly, the errors take hold quickly, neutralising the virus and preventing further spread. This is one of the first demonstrations of lethal mutagenesis as a method of fighting viruses in their natural hosts and suggests that it may be possible to tackle other RNA viruses in the same way.
"Norovirus is an unpleasant bug that spreads quickly," says Professor Goodfellow, a Wellcome Trust Senior Fellow, who led the study. "Most of us will have experienced it at some point and will know that the only option is to ride out an infection, drinking plenty of fluids. But some patients get infections that can last months or years, and this has a real impact on their quality of life. The ease with which infections spread, particularly in places such as hospitals, schools and cruise ships, and the potentially serious health problems norovirus can cause people with weakened immune systems means that we desperately need a way to treat infection."
Dr Armando Arias, first author, adds: "Our work in mice is very promising and shows that favipiravir can make the virus mutate itself to death. It suggests that as well as treating infected individuals, the drug may also be useful in preventing infection during an outbreak. The next steps will be to test whether this drug is safe and effective at treating patients, too."
Story Source:
The above story is based on materials provided by University of CambridgeNote: Materials may be edited for content and length.

Journal Reference:
  1. Armando Arias, Lucy Thorne, Ian Goodfellow. Favipiravir elicits antiviral mutagenesis during virus replication in vivoeLife, 2014; 3 DOI:10.7554/eLife.03679

The literature describes Listeria as ubiquitous bacteria with widespread occurrence. Yet they only become a problem for humans and animals when they contaminate food processing facilities, multiply, and enter the food chain in high concentrations. An infection with Listeria monocytogenes can even be fatal for humans or animals with weakened immune systems.
The collected soil and water samples were analyzed in the laboratory for their identity. Credit: Beatrix Stessl/Vetmeduni Vienna

Listeria in soil or water are not dangerous
"Listeria in  or water represent a relatively low risk to humans," explains study director Beatrix Stessl. "The concentrations are too low. The aim of our study was to ascertain where Listeria occur and which species and genotypes were prevalent there." Martin Wagner, head of the Institute of Milk Hygiene, adds: "This information can help us to better understand the mechanisms through which these bacteria are spread."
Flooding favours Listeria contamination
Over a period from 2007 to 2009, first author Kristina Linke and her colleagues collected nearly 500 soil and 70 water samples from three Austrian regions: the eastern Alps, the Donauauen National Park adjacent to the river Danube, and Lake Neusiedl. The study regions involved natural, non-agricultural areas. Of all samples, 30 percent were detected positive for Listeria. Of these, 6 percent were contaminated with Listeria monocytogenes, the only species that is potentially dangerous for both humans and animals. L. monocytogenes was detected especially near the rivers Schwarza and Danube. Particularly high rates of the bacteria in soil and water samples were registered in September 2007 during extensive flooding in the region.
In most regions, the researchers found only Listeria that are non-pathogenic to humans.
The species Listeria ivanovii, which is potentially dangerous for , was found mainly in mountainous regions where the bacteria are presumably excreted by wildlife species. The non-pathogenic Listeria seeligeri was most frequently isolated in the region around Lake Neusiedl, which is likely explained by the waterfowl population in this area.
No Listeria were isolated in high-altitude mountain regions. The researchers explain the greater contamination at lower altitudes with the proximity to farms, agricultural land and the urban environment.
Antibiotic-resistant Listeria in soil
Although Listeria that contaminate food are generally not considered to be resistant to antibiotics, Stessl and her team found several Listeria strains in soil samples which resisted treatment with antibiotics. The bacteria have developed resistance. Stessl sees the possible causes as follows: "A number of soil microorganisms, such as fungi, naturally produce antibiotics. Listeria which are constantly exposed to these substances in the soil probably develop resistance. We believe, however, that the development of particularly high-resistant strains of Listeria can be explained by the proximity to agricultural land and the urban environment."
More information: "Reservoirs of Listeria species in three environmental ecosystems," by Kristina Linke, Irene Rückerl, Katharina Brugger, Renata Karpiskova, Julia Walland, Sonja Muri-Klinger, Alexander Tichy, Martin Wagner und Beatrix Stessl was published in the Journal Applied and Environmental MicrobiologyDOI: 10.1128/AEM.01018-14

The environment significantly influences whether or not a certain bacterium will block mosquitoes from transmitting malaria, according to researchers at Penn State. "Bacteria in the genus Wolbachia represent a promising new tool for controlling malaria due to their demonstrated ability to block the development of the pathogen within Anopheles mosquitoes -- the mosquitoes that are responsible for the transmission of malaria parasites in many parts of the world," said Courtney Murdock, postdoctoral researcher, Center for Infectious Disease Dynamics and Department of Entomology, Penn State. "However, much of the work on the Wolbachia-malaria interaction has been conducted under highly simplified laboratory conditions. In this study, we investigated the ability of Wolbachia to block transmission of malaria -- Plasmodium -- parasites across variable environmental conditions, which are more reflective of conditions in the field."
Oocyst -- non-infectious stage of malaria -- of Plasmodium yoelii (rodent malaria) attach to the wall of a mosquito midgut.
Credit: Krijn Paaijmans, Universitat de Barcelona

The researchers used a species of malaria parasite --Plasmodium yoelii -- that affects rodents and the mosquito Anopheles stephensi as a model system to investigate whether Wolbachia would block the ability of the malaria parasite to infect the mosquitoes. The scientists divided the mosquitoes into an uninfected control group and a group infected with Wolbachia. Next, the team raised all groups of mosquitoes in incubators set to different experimental temperatures -- 68, 72, 75, 79 and 82 degrees Fahrenheit.
The scientists found that at 82 degrees Fahrenheit, Wolbachia reduced the number of mosquitoes infected by malaria parasites, the number of malaria parasites within each mosquito and the intensity of oocysts -- non-infectious cysts created by malaria parasites that occur on the outer lining of a mosquito's midgut. At 75 degrees Fahrenheit, Wolbachia had no effect on prevalence of malaria parasites, but increased oocyst intensity. At 68 degrees Fahrenheit, Wolbachia had no effect on prevalence of parasites or intensity of oocysts.
In addition, the team identified a previously undiscovered effect of Wolbachia. Infection with the bacterium reduced the development of sporozoites across all temperatures, suggesting that Wolbachia and malaria parasites may compete for similar hosts.
"Typically, the more oocysts a mosquito has on its midgut, the more sporozoites it produces," Murdock said. "So, depending on the environmental temperature, Wolbachia either reduced, enhanced or had no effect on the number of oocysts. At 75 degrees Fahrenheit, Wolbachia-infected mosquitos had three times the numbers of oocysts relative to uninfected mosquitoes. Thus, we would predict these mosquitoes to produce more sporozoites. But instead we see that this is not the case, and that is because Wolbachia infection significantly reduces the number of sporozoites produced per oocyst regardless of the environmental temperature. This effect counteracts the enhancement we see at 75 degrees Fahrenheit. How the influence of Wolbachia on parasite establishment and the production of sporozoites under different temperatures plays out to ultimately affect transmission remains to be determined."
The researchers published their results in a recent issue of Nature Scientific Reports.
According to Murdock, the team's results demonstrate that the transmission-blocking ability of Wolbachia is significantly influenced by the environment.
"These results suggest that the development of this promising control technology requires an improved understanding of how mosquitoes, Wolbachia and malaria parasites will interact in diverse transmission settings," she said. "The worst-case scenario is not whether this technology will be ineffective under particular environmental conditions, but whether or not there is a possibility that certain environments will actually enhance malaria transmission by Wolbachia."
The researchers plan to duplicate their experiment using a species of malaria parasite that affects humans to determine whether or not the temperature effects they observed in the mouse model system also will be observed in a human system. The team plans to explore the effects of additional environmental variation -- such as daily temperature fluctuation and differential access to food resources in the mosquito larval and adult environments -- on the transmission-blocking ability of Wolbachia.
Story Source:
The above story is based on materials provided by Penn StateNote: Materials may be edited for content and length.

Journal Reference:
  1. Courtney C. Murdock, Simon Blanford, Grant L. Hughes, Jason L. Rasgon, Matthew B. Thomas. Temperature alters Plasmodium blocking by Wolbachia.Scientific Reports, 2014; 4 DOI: 10.1038/srep03932

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