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Battling Super Bugs

Novel delivery system holds promise for first Chlamydia vaccine
  • UMass Amherst Microbiologist, Wilmore Webley

“We are tackling one of the major issues that confront Chlamydia vaccinologists right now which is the delivery system."
- Wilmore Webley

Microbiologist Wilmore Webley is unraveling one of the great mysteries in the world of vaccinology. His development of a novel delivery mechanism for vaccine antigens holds hope for a first-ever vaccine to prevent infection from the Chlamydia family of bacteria.

The scope of Webley’s work is far broader than one who thinks of Chlamydia as just a sexually transmitted infection might assume.  His investigations and that of others in the field have found a Chlamydia family member, Chlamydia pneumoniae, in atherosclerotic plaques, in the joints of patients with reactive arthritis, in the brains of Alzheimer’s patients, and in approximately 70% of pediatric asthmatics whose disease does not respond to conventional corticosteroid treatment.

Its communicability is far more widespread than sexual contact.

“You inhale it,” says Webley. “That’s basically how you get Chlamydia pneumoniae. It can be spread from hand to hand contact, through aerosols or respiratory secretions.” For these reasons, he says “by the time you’re twenty years old, fifty percent of us have evidence of exposure to Chlamydia pneumoniae.”

One reason for its presence in such varied conditions as arthritis and chronic respiratory disease is the bacteria's strength and resilience. “Chlamydia is an obligate intracellular pathogen; it lives inside of cells. It doesn’t need the protection of a biofilm like extracellular bacteria do. It is already protected,” says Webley. He describes the human cell as “one of the most hostile environments on the planet, so for a bug to feel comfortable enough to live within a human cell it must have really amazing capabilities.”

Chlamydia trachomatis, a cousin of C. pneumoniae is the leading cause of preventable blindness worldwide, especially in parts of Africa and Asia where it is endemic and can be transmitted by flies. In the U.S. and other developed countries C. trachomatis is also the most frequently reported bacterial sexually transmitted disease. Two reasons for its ubiquity is the lack of early detection (70-75% of people who are infected with C. trachomatis are asymptomatic initially), and the fact that there is no Chlamydia vaccine.

That may soon change. “We have the product,” Webley says.  “We literally just published on this at the end of last year. In fact, it was just listed in a review (in The Journal of Expert Reviews Vaccines) as one of the platforms with the greatest potential as a Chlamydia vaccine.”

The need for such a product is far reaching.  Chlamydia trachomatis is the number one cause of preventable blindness worldwide. In Asia and Africa, poor sanitation enables chlamydial infections that often result in conjunctivitis and other blindness-causing condition which require surgery. The afflicted don’t often have the funds for treatment.

“That is the reason we need the vaccine,” says Webley.

The reason a vaccine is so long in coming, Webley explains, is the lack of an effective delivery mechanism for vaccine antigens.  “We are tackling one of the major issues that confront Chlamydia vaccinologists right now which is the delivery system. How do you take those proteins that you want the immune system to make a response against and deliver them to the body in a safe way?”

Webley believes the answer lies in gas vesicles produced by salt loving microbes, Halobacteria salinarium.

 “We have already figured out which proteins on a bug like Chlamydia might be useful in making a vaccine,” says Webley. “The gas vesicles look like a football. So we’ve gone in and taken the genes that make up this football and spliced our proteins of interest into the skin of it, so when you look at this football, you not only see the proteins that make it up structurally, you also see our Chlamydia proteins displayed on its outer surface.” The fact that multiple proteins are being displayed at the same time results in the induction of a more robust immune response.

Regarding safety, Webley says Halobacteria live in salty foods like soy sauce or beef jerky, and the gas vesicles they produce are already being broken down and digested by the human body every day. “They cause no pathology to our body. The human immune system  sees all the proteins spliced onto the gas vesicles, and then breaks them down and eliminates them safely over time,” says Webley.

Testing, and applying the technology to other problems is next, says Webley. A move into the new Life Science Laboratories, the latest building to go up in the UMass Amherst life sciences precinct, will help facilitate that. The Life Science Laboratories are designed in a way to allow for a collaborative research environment so that the work of people like Webley will help to inform and expand the work of other researchers. This set up will allow for a more efficient sharing of new knowledge, a creation of synergy between disciplines, and shorten the time between which scientific breakthroughs become practical application for the human population at large. This is especially true of discoveries such as Webley’s that have very broad and immediate ramifications for research being done on other diseases or in other fields.

“The great thing about the new Life Science Laboratories is that we will be in a cluster of individuals from whom we’ll be able to learn new techniques, use new equipment, and create new knowledge from those collaborations. People like Yasu Morita who is a new faculty member in our department. In fact, we just wrote up a proposal together. He is also looking at being able to make a vaccine/preventative cure for TB, and this gas vesicle display I spoke about could also be able to display TB antigens, so that might be a very strong area of collaboration for both of us.”  In this way, Webley’s team is already accelerating the rate at which scientific breakthroughs may occur.

Ryan Morin