Corporate Banner
Satellite Banner
Biologics & Bioprocessing
Scientific Community
 
Become a Member | Sign in
Home>News>This Article
  News
Return

A Key Step Toward a Safer Strep Vaccine

Published: Friday, June 13, 2014
Last Updated: Friday, June 13, 2014
Bookmark and Share
Gene discovery identifies molecular pathway to potential preventive treatment.

An international team of scientists, led by researchers at the University of California, San Diego School of Medicine, have identified the genes encoding a molecule that famously defines Group A Streptococcus (strep), a pathogenic bacterial species responsible for more than 700 million infections worldwide each year.

The findings, published online in the June 11 issue of Cell Host & Microbe, shed new light on how strep bacteria resists the human immune system and provides a new strategy for developing a safe and broadly effective vaccine against strep throat, necrotizing fasciitis (flesh-eating disease) and rheumatic heart disease.

“Most people experience one or more painful strep throat infections as a child or young adult,” said senior author Victor Nizet, MD, professor of pediatrics and pharmacy. “Developing a broadly effective and safe strep vaccine could prevent this suffering and reduce lost time and productivity at school and work, estimated to cost $2 billion annually.”

Efforts to develop such a vaccine have been significantly hindered by complexities in how the human immune system reacts to the bacterial pathogen. Specifically, some patients with strep infections produce antibodies that cross-react with their own heart valve tissue, leading to rheumatic fever and heart damage. Though rare in the United States, rheumatic fever remains common in some developing countries and causes significant disability and death.

The Cell Host & Microbe study suggests a way to circumvent the damaging autoimmune response triggered by strep. Specifically, the researchers noted that the cell wall of strep is composed primarily of a single molecule known as the group A carbohydrate (or GAC) which, in turn, is built from repeating units of the bacterial sugar rhamnose and the human-like sugar N-acetylglucosamine (GlcNAc).

Previous research has indicated that GlcNAc sugars present in GAC may be responsible for triggering production of heart-damaging antibodies in some patients. Nizet said the latest findings corroborate this model, and suggest that eliminating the pathogen’s ability to add GlcNAc sugars to GAC could be the basis for a safe vaccine.

“In this study, we discovered the strep genes responsible for the biosynthesis and assembly of GAC, the very molecule that defines the pathogen in clinical diagnosis,” said first author Nina van Sorge, PharmD, PhD, a former postdoctoral fellow at UC San Diego who now leads her own laboratory at Utrecht University Medical Center in the Netherlands. “This discovery allowed us to generate mutant bacterial strains and study the contribution of GAC to strep disease.”

The researchers found that a mutant strep strain lacking the human-like GlcNAc sugar on the GAC molecule exhibited normal bacterial growth and expressed key proteins known to be associated with strep virulence, but was easily killed when exposed to human white blood cells or serum. The mutant strep bacteria also lost the ability to produce severe disease in animal infection models.

“Our studies showed that the GlcNAc sugar of GAC is a critical virulence factor allowing strep to spread in the blood and tissues,” van Sorge said. “This is likely important for the rare, but deadly, complications of strep infection such as pneumonia, necrotizing fasciitis and toxic shock syndrome.”

The researchers also identified a way to remove the problematic GlcNAc sugar so that a mutant form of the bacteria with only rhamnose-containing GAC could be purified and tested as a vaccine antigen.

“We showed that antibodies produced against mutant GAC antigen helped human white blood cells kill the pathogen and protected mice from lethal strep infection,” said Jason Cole, PhD, a visiting project scientist from the University of Queensland, Australia, and co-lead author of the paper. “Because GAC is present in all strep strains, this may represent a safer antigen for inclusion in a universal strep vaccine.”

Researchers plan to assess the new modified antigen against other candidates in advanced strep throat vaccine tests in nonhuman primates beginning later this year in Atlanta, Georgia, funded by the National Health and Medical Research Council of Australia.

“It is satisfying to find that a fundamental observation regarding the genetics and biochemistry of the pathogen can have implications not only for strep disease pathogenesis, but also for vaccine design,” Nizet said.


Further Information
Access to this exclusive content is for Technology Networks Premium members only.

Join Technology Networks Premium for free access to:

  • Exclusive articles
  • Presentations from international conferences
  • Over 2,500+ scientific posters on ePosters
  • More than 3,700+ scientific videos on LabTube
  • 35 community eNewsletters


Sign In



Forgotten your details? Click Here
If you are not a member you can join here

*Please note: By logging into TechnologyNetworks.com you agree to accept the use of cookies. To find out more about the cookies we use and how to delete them, see our privacy policy.

Related Content

Novel Drug Targeting Leukemia Cells Enters Clinical Trial
Phase 1 human clinical trial to assess the safety and efficacy of a new monoclonal antibody for CLL patients.
Friday, September 19, 2014
Hormone Plays Surprise Role in Fighting Skin Infections
Previously associated with calcium homeostasis, hormone now found to hold critical role in boosting AMP expression.
Friday, May 25, 2012
Scientific News
Immunotherapy Agent Benefits Patients with Drug-Resistant Multiple Myeloma in First Human Trial
Daratumumab proved generally safe in patients, even at the highest doses.
Inciting an Immune Attack On Cancer Cells
A new minimally invasive vaccine that combines cancer cells and immune-enhancing factors could be used clinically to launch a destructive attack on tumors.
Less May Be More in Slowing Cholera Epidemics
Mathematical model shows more cases may be prevented and more lives saved when using one dose of cholera vaccine instead of recommended two doses.
NIH Launches Human RSV Study
Study aims to understand infection in healthy adults to aid development of RSV medicines, vaccines.
Flu Remedies Help Combat E. coli Bacteria
Physiologists from the University of Zurich have now discovered why the intestinal bacterium Escherichia coli (E. coli) multiplies heavily and has an inflammatory effect.
'Fountain of Youth' Protein Points to Possible Human Health Benefit
Patients with higher blood levels of growth factor have lower risk of cardiovascular problems.
Lemon Juice and Human Norovirus
Citric acid may prevent the highly contagious norovirus from infecting humans, scientists discovered from the German Cancer Research Center.
Study Backs Flu Vaccinations for Elderly
Brown University researchers found vaccines well matched to the year’s flu strain significantly reduce deaths and hospitalizations compared to when the match is poor, suggesting that vaccination indeed makes a difference.
Inciting an Immune Attack on Cancer Cells
A new minimally invasive vaccine that combines cancer cells and immune-enhancing factors could be used clinically to launch a destructive attack on tumors.
Protein Found to Play a Key Role in Blocking Pathogen Survival
Calprotectin fends off microbial invaders by limiting access to iron, an important nutrient.
SELECTBIO

Skyscraper Banner
Go to LabTube
Go to eposters
 
Access to the latest scientific news
Exclusive articles
Upload and share your posters on ePosters
Latest presentations and webinars
View a library of 1,800+ scientific and medical posters
2,500+ scientific and medical posters
A library of 2,500+ scientific videos on LabTube
3,700+ scientific videos
Close
Premium CrownJOIN TECHNOLOGY NETWORKS PREMIUM FREE!