Live oral Shigella vaccine licensed to PATH

Nov 24 2008

The University of Maryland, Baltimore (UMB) has licensed a pediatric vaccine against Shigella bacteria to PATH, an international nonprofit group, to support clinical trials, with the goal of developing a vaccine suitable for children in resource-poor countries.

Each year, an estimated 1.1 million people die from Shigella infections, a major cause of diarrhea and dysentery, reports the World Health Organization (WHO). More than 60 percent of the deaths reported were children less than five years of age.

"The live oral Shigella vaccine created at the School of Medicine's Center for Vaccine Development is the culmination of more than a decade of dedication to serving the chronically underserved, and this partnership is critical to achieving a better world for those populations," says Libby Hart-Wells, PhD, an executive director at UMB's Office of Research and Development.

The Center for Vaccine Development, headed by Myron Levine, MD, DTPH, has earned an international reputation for creating and testing vaccines against cholera, typhoid, malaria and other infectious diseases, including smallpox, West Nile virus, and avian flu.

Levine says, "The good news is that PATH deals with manufacturers in developing countries and that could assure that it would have a source of a vaccine producer for the developing world."

PATH collaborates with public and private sector partners to provide appropriate health technologies and vital strategies to improve global health and well-being. PATH is based in Seattle.

Richard Walker, PhD, director of PATH's Enteric Vaccine Initiative, calls the UMB Shigella vaccine candidate promising. He adds, "PATH is committed to accelerating the development of safe, effective, and affordable vaccines against the leading causes of diarrheal disease including shigellosis and making them available to children in the world's poorest countries as quickly as possible."

Levine also hopes that, when the Shigella project moves to late clinical trials, a large pharmaceutical company will finalize a version of the vaccine to help protect the 580,000 cases of shigellosis each year among travelers and military personnel (according to WHO). "That also may still come to pass. We are very early in the process," Levine adds.

Shigella species are transmitted by ingestion of contaminated food or water, or by person-to-person contact, the most common source of transmission. The bacteria invade the lower intestines and spread from cell-to-cell.

In the developing world, treatment of shigellosis is in a state of crisis because of the bacteria's growing resistance to antibiotics. "The [different] Shigella bacteria, which cause disease in many parts of the world, are commonly resistant to multiple antibiotics, and, in some places, we are down to only one antibiotic to treat the disease," says Levine. He says the vaccine to prevent shigellosis could have a dramatic impact "if the vaccine truly works, if we have a manufacturer, and if the GAVI accepts it," referring to the powerful immunization advancement group, GAVI Alliance in Geneva.

The UMB vaccine candidate is a multivalent vaccine designed to ultimately target five disease-causing strains of the bacteria. The Center for Vaccine Development team, which developed the vaccine also included Eileen Barry, PhD, associate professor; Karen Kotloff, MD, professor; Marcelo Sztein, MD, professor; Marcela Pasetti, PhD, associate professor; and Jakub Simon, MD, assistant professor.