University Leading Nation’s Largest Smallpox Vaccine Study

November 05, 2002

Volunteers in the Rochester area will have another opportunity to be vaccinated against smallpox, thanks to two new studies just beginning at the University of Rochester Medical Center.

Rochester doctors and nurses have been chosen to lead the largest study of smallpox vaccine to date, a nationwide study of approximately 900 patients that will be conducted at seven sites around the country, including Rochester. Approximately 200 people in the Rochester area who were vaccinated against the disease as children will receive a booster shot as part of the study. John Treanor, M.D., associate professor of medicine and director of the medical center’s Vaccine and Treatment Evaluation Unit, will lead the national study, coordinating doctors at all seven sites and guiding the effort to evaluate the results.

Last year, shortly after the Sept. 11 attack, 170 people were vaccinated against smallpox at the university, part of a larger nationwide study which determined that a diluted form of the vaccine could protect people as well as a full dose. The study was conducted because, even though smallpox has been eradicated in nature, officials are fearful that the agent could be used in a bioterrorism attack.

While the previous study looked at adults who had never been vaccinated – nearly everyone born after 1972 – this year’s study will focus on adults who were vaccinated as children, to see how a booster shot affects the protection they have against the disease.

Like last year’s study, participants will receive either a standard dose of vaccine, one-fifth the standard dose, or one-tenth the standard dose. Doctors and nurses will monitor their immune response and side effects to determine the most effective dose.

“It’s important to know which dose works best for this group of people,” says Treanor. “This is very similar to the study last year, except now we’re looking at people who did receive the vaccine as children. It’s crucial to protect this group as well.”

Doctors aren’t sure just how well such people are currently protected against the disease. While it’s known that some diseases, like tetanus, require repeated immunization, the need to administer repeated doses is less clear with smallpox. With the threat of bioterrorism, officials are exploring the issue more thoroughly.

In a second study that will involve 45 people in the Rochester area, doctors and scientists are teaming up to analyze exactly how the smallpox vaccine works in the body, a line of research that wasn’t possible when the vaccine was last widely used in the early 1970s. The study will include about 15 volunteers who have never received the vaccine; 15 who were vaccinated as part of last year’s study; and 15 who were vaccinated as children before 1972. Each participant will receive a single dose of the vaccine, and then doctors will check their immune response for six months.

Besides Treanor, scientists involved in this study are immunologists David Topham, Ph.D., and Tim Mosmann, Ph.D., of the David H. Smith Center for Vaccine Biology and Immunology; and molecular biologist Mark Sullivan, Ph.D., of the Center for Human Genetics and Molecular Pediatric Disease.

The scientists will look at initial immune responses as well as “immune memory,” or the way our body remembers an infectious invader and then stays geared up to recognize and fight that infection, oftentimes for the rest of our lives. Usually, with a common infection like the flu, it’s difficult for scientists to know exactly when or how often a person has been exposed.

But since smallpox has been eradicated in nature, scientists know that people have not been exposed naturally, and that any immune response must be a result of vaccination. As one of only a handful of sites where volunteers have been immunized in recent years, the Rochester region offers a unique opportunity for researchers like Mosmann and Topham to learn more.

“There are very, very few studies that describe the cellular immune response to smallpox,” says Topham. “The modern immunological techniques common in laboratories today simply didn’t exist 30 or 40 years ago, and so we really know very little about the body’s immune response to the virus. Now we know, for instance, that killer T cells are part of the body’s response to a viral infection, but 30 years ago we didn’t even know they existed.”

The study will extend research pioneered by Mosmann that is aimed at measuring the ability of individual killer T cells to destroy cells infected by the virus. While patients and doctors can tell generally whether a patient is getting sicker or getting better from an infection, inside the body it’s a cell-by-cell battleground as killer T cells and other immune cells fend off viral invaders like smallpox. Volunteers in the study will enable Mosmann and Topham to get a remarkably close-up look at the process of how well an individual T cell is able to find and kill a cell infected with smallpox.

In another portion of the latest study, Sullivan plans to use the blood of some volunteers to create a supply of antibodies that focus specifically on the vaccinia virus, the virus used in the vaccine. Such antibodies are the body’s way of flagging down a molecular invader for other cells to attack and destroy.

Creating the antibody supply from the blood of someone who has recently been immunized helps scientists hone in on the antibodies they need much faster than they otherwise could, and to amplify them to create a large supply, says Sullivan. Such a supply could be used to treat people who have severe side effects from being vaccinated, and it might even be useful as a treatment for smallpox, the scientists say.

Sullivan, a molecular biologist who has one of the largest libraries of human antibodies in the world, had proposed the project two years ago and found renewed interest after last year’s terrorist attack.

 Anyone interested in volunteering must be an adult in good health. Volunteers also cannot have eczema or a condition that weakens the immune system. Prospective participants are excluded if they have daily close contact with a woman who is pregnant or with children under one year of age. Women who are pregnant or breastfeeding are not eligible.

Anyone interested in participating in either study should call (585) 273-3990. Both studies are funded by the National Institute of Allergy and Infectious Disease.

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