New study shows viruses can have immune systems

A pirate phage commandeers the immune system of bacteria

2013-02-28

(Press-News.org) BOSTON (February 27, 2013, embargoed until 1 p.m. US ET) — A study published today in the journal Nature reports that a viral predator of the cholera bacteria has stolen the functional immune system of bacteria and is using it against its bacterial host. The study provides the first evidence that this type of virus, the bacteriophage ("phage" for short), can acquire a wholly functional and adaptive immune system.

The phage used the stolen immune system to disable – and thus overcome – the cholera bacteria's defense system against phages. Therefore, the phage can kill the cholera bacteria and multiply to produce more phage offspring, which can then kill more cholera bacteria. The study has dramatic implications for phage therapy, which is the use of phages to treat bacterial diseases. Developing phage therapy is particularly important because some bacteria, called superbugs, are resistant to most or all current antibiotics.

Until now, scientists thought phages existed only as primitive particles of DNA or RNA and therefore lacked the sophistication of an adaptive immune system, which is a system that can respond rapidly to a nearly infinite variety of new challenges. Phages are viruses that prey exclusively on bacteria and each phage is parasitically mated to a specific type of bacteria. This study focused on a phage that attacks Vibrio cholerae, the bacterium responsible for cholera epidemics in humans.

Howard Hughes Medical Institute investigator Andrew Camilli, Ph.D., of Tufts University School of Medicine led the research team responsible for the surprising discovery.

First author Kimberley D. Seed, Ph.D., a postdoctoral fellow in Camilli's lab, was analyzing DNA sequences of phages taken from stool samples from patients with cholera in Bangladesh when she identified genes for a functional immune system previously found only in some bacteria (and most Archaea, a separate domain of single-celled microorganisms).

To verify the findings, the researchers used phage lacking the adaptive immune system to infect a new strain of cholera bacteria that is naturally resistant to the phage. The phage were unable to adapt to and kill the cholera strain. They next infected the same strain of cholera bacteria with phage harboring the immune system, and observed that the phage rapidly adapted and thus gained the ability to kill the cholera bacteria. This work demonstrates that the immune system harbored by the phage is fully functional and adaptive.

"Virtually all bacteria can be infected by phages. About half of the world's known bacteria have this adaptive immune system, called CRISPR/Cas, which is used primarily to provide immunity against phages. Although this immune system was commandeered by the phage, its origin remains unknown because the cholera bacterium itself currently lacks this system. What is really remarkable is that the immune system is being used by the phage to adapt to and overcome the defense systems of the cholera bacteria. Finding a CRISPR/Cas system in a phage shows that there is gene flow between the phage and bacteria even for something as large and complex as the genes for an adaptive immune system," said Seed.

"The study lends credence to the controversial idea that viruses are living creatures, and bolsters the possibility of using phage therapy to treat bacterial infections, especially those that are resistant to antibiotic treatment," said Camilli, professor of Molecular Biology & Microbiology at Tufts University School of Medicine and member of the Molecular Microbiology program faculty at the Sackler School of Graduate Biomedical Sciences at Tufts University.

Camilli's previous research established that phages are highly prevalent in stool samples from patients with cholera, implying that phage therapy is happening naturally and could be made more effective. In addition, a study published by Camilli in 2008 determined that phage therapy works in a mouse model of cholera intestinal infection.

The team is currently working on a study to understand precisely how the phage immune system disables the defense systems of the cholera bacteria. This new knowledge will be important for understanding whether the phage's immune system could overcome newly acquired or evolved phage defense systems of the cholera bacteria, and thus has implications for designing an effective and stable phage therapy to combat cholera.

###Additional authors are David W. Lazinski, Ph.D., senior research associate in the Camilli lab at Tufts University School of Medicine, and Stephen B. Calderwood, M.D., Morton N. Swartz, M.D. academy professor of medicine at Harvard Medical School, and chief, division of infectious disease and vice-chair, department of medicine at Massachusetts General Hospital.

Research reported in this publication was supported by the National Institute of Allergies and Infectious Diseases of the National Institutes of Health under award numbers R01AI55058, R01AI045746, and R01AI058935.

Seed, K.D., Lazinski, D.W., Calderwood, S.B., and Camilli, A. (2013). A bacteriophage encodes its own CRISPR/Cas adaptive response to evade host innate immunity. Nature, vol 494, issue 7438, pp 489 DOI: 10.1038/nature11927

About Tufts University School of Medicine and the Sackler School of Graduate Biomedical Sciences Tufts University School of Medicine and the Sackler School of Graduate Biomedical Sciences at Tufts University are international leaders in innovative medical education and advanced research. The School of Medicine and the Sackler School are renowned for excellence in education in general medicine, biomedical sciences, special combined degree programs in business, health management, public health, bioengineering and international relations, as well as basic and clinical research at the cellular and molecular level. Ranked among the top in the nation, the School of Medicine is affiliated with six major teaching hospitals and more than 30 health care facilities. Tufts University School of Medicine and the Sackler School undertake research that is consistently rated among the highest in the nation for its effect on the advancement of medical science.

If you are a member of the media interested in learning more about this topic, or speaking with a faculty member at the Tufts University School of Medicine or another Tufts health sciences researcher, please contact Siobhan Gallagher at 617-636-6586 or siobhan.gallagher@tufts.edu.

ELSE PRESS RELEASES FROM THIS DATE:

Songbirds' brains coordinate singing with intricate timing

2013-02-28

As a bird sings, some neurons in its brain prepare to make the next sounds while others are synchronized with the current notes—a coordination of physical actions and brain activity that is needed to produce complex movements, new research at the University of Chicago shows. In an article in the current issue of Nature, neuroscientist Daniel Margoliash and colleagues show, for the first time, how the brain is organized to govern skilled performance—a finding that may lead to new ways of understanding human speech production. The new study shows that birds' physical ...

The NHL drafts the wrong players due to birthday bias

2013-02-28

ALLENDALE, Mich. — A hockey player's birthday strongly biases how professional teams assess his talent, according to a new study by Grand Valley State University researchers. The findings were published in the online journal PLOS ONE at http://dx.plos.org/10.1371/journal.pone.0057753. The research, led by Robert Deaner, associate professor of psychology at Grand Valley State, shows that, on average, National Hockey League (NHL) draftees born between July and December are much more likely than those born in the first three months of the year to have successful careers. ...

Lipid researcher, 98, reports on the dietary causes of heart disease

2013-02-28

CHAMPAIGN, Ill. — A 98-year-old researcher argues that, contrary to decades of clinical assumptions and advice to patients, dietary cholesterol is good for your heart – unless that cholesterol is unnaturally oxidized (by frying foods in reused oil, eating lots of polyunsaturated fats, or smoking). The researcher, Fred Kummerow, an emeritus professor of comparative biosciences at the University of Illinois, has spent more than six decades studying the dietary factors that contribute to heart disease. In a new paper in the American Journal of Cardiovascular Disease, he ...

Sitting less and moving about more could be more important than vigorous exercise to reduce your risk of type 2 diabetes

2013-02-28

New research led at the University of Leicester reveals that individuals at high risk of developing type 2 diabetes would benefit from being told to sit less and move around more often- rather than simply exercising regularly. The experts suggest that reducing sitting time by 90 minutes in total per day could lead to important health benefits. Currently, at risk patients are advised to engage in moderate-to-vigorous physical activity (MVPA) for at least 150 mins per week. But the new study published in Diabetologia (The journal of the European Association for the Study ...

Canadian adult obesity at historic high

2013-02-28

Obesity rates across Canada are reaching alarming levels and continue to climb, according to a new University of British Columbia study. Published today in the Canadian Journal of Public Health, the study provides the first comprehensive look at adult obesity rates across Canada since 1998, complete with "obesity maps." "Being obese or overweight significantly increases the risk of chronic illnesses, such as heart disease, diabetes, and some cancers," says study lead author, Prof. Carolyn Gotay in UBC's School of Population and Public Health. "Our analysis shows that ...

How much will I be charged?

2013-02-28

It's a basic, reasonable question: How much will this cost me? For patients in the emergency room, the answer all too often is a mystery. Emergency departments play a critical role in health care, yet consumers typically know little about how medical charges are determined and often underestimate their financial responsibility -- then are shocked when the hospital bill arrives. A new study led by UC San Francisco highlights the problem by identifying giant price swings in patient charges for the 10 most common outpatient conditions in emergency rooms across the country. Out-of-pocket ...

How much protection is enough?

2013-02-28

Protection of marine areas from fishing increases density and biomass of fish and invertebrates (such as lobster and scallops) finds a systematic review published in BioMed Central's open access journal Environmental Evidence. The success of a protected area was also dependent on its size and on how it was managed, however even partial protection provides significant ecological benefits. Marine ecosystems worldwide are suffering from a loss of biodiversity due to destruction of food chains and habitats. Increasingly areas are being set aside to protect sensitive environments ...

First signs of heart disease seen in newborns of overweight/obese mums

2013-02-28

The walls of the body's major artery - the aorta - are already thickened in babies born to mums who are overweight or obese, finds a small study published online in the Fetal and Neonatal Edition of Archives of Disease of Childhood. Importantly, this arterial thickening, which is a sign of heart disease, is independent of the child's weight at birth - a known risk factor for later heart disease and stroke. And it may explain how overweight/obese mums could boost their children's subsequent risk of cardiovascular disease, suggest the authors, who point out that more ...

Every degree fall in winter air temperature equals 1 percent drop in ambulance response time

2013-02-28

[Ambulance call-outs and response times in Birmingham and the impact of extreme weather and climate change Online First doi 10.1136/emermed-2012-201817] Every one degree fall in outside air temperature during the winter corresponds to a drop in ambulance response time of more than 1 per cent, reveals research published online in Emergency Medicine Journal. Increased demand and treacherous road conditions during the winter months combine to stretch ambulance services in England, which have a target of reaching 75% of immediately life-threatening (category A) calls within ...

Discovery opens door to multipronged attack against skin common cancer, Stanford study shows

2013-02-28

STANFORD, Calif. — Hailed as a major step forward in the effort to develop targeted cancer therapies, a recently approved drug for the most common type of skin cancer has been a mixed blessing for patients. Although the initial response is usually dramatic, the tumors often recur as the cancer becomes resistant to treatment. Now researchers at the Stanford University School of Medicine have identified a second way to block the activity of the signaling cascade, called the Hedgehog pathway, that is abnormally active in these cancers. The researchers hope the new approach ...

World’s leading science competition identifies 19 breakthrough solutions around the globe with greatest potential to tackle the planetary crisis

Meta-analysis finds Transcendental Meditation reduces post-traumatic stress disorder (PTSD) symptoms across populations and cultures

AACR: Five MD Anderson researchers honored with 2025 Scientific Achievement Awards

How not to form a state: Research reveals how imbalanced social-ecological acceleration led to collapse in early medieval Europe

DDT residues persist in trout in some Canadian lakes 70 years after insecticide treatment, often at levels ten times that recommended as safe for the wildlife which consumes the fish

New study shows viruses can have immune systems

ELSE PRESS RELEASES FROM THIS DATE:

LAST 30 PRESS RELEASES: