Each year, millions of people contract serious diarrheal illnesses typically from contaminated food and water. Among the biggest causes of diarrheal diseases are the bacteria Shigella and enterotoxigenic Escherichia coli (ETEC), and researchers at the University of Maryland School of Medicine are testing a vaccine designed to offer protection against these serious pathogens.

Wilbur Chen, MD, MS, associate professor of medicine, is principal investigator, and Eileen Barry, PhD, professor of medicine, is co-principal investigator for this research, which is being funded by a $4.5 million agreement with Emergent BioSolutions, a global life sciences company focused on addressing public health threats, including travel health diseases.

Chen and Barry will conduct early clinical trials of a combined Shigella-ETEC vaccine called “CVD 1208S-122,” a vaccine comprised of a weakened live strain of Shigella expressing protective antigens from ETEC that was developed at UMSOM’s Center for Vaccine Development and Global Health (CVD).

Their research will test the safety, tolerability and potential protection of oral doses of the prototype Shigella-ETEC vaccine. The trials will include testing how the immune system in healthy adults responds to varying doses of the vaccine. The goal is to determine the safety and best dosing of the vaccine, which could ultimately protect millions of people around the world who are at most risk to diarrheal diseases.

“Our goal here is to develop a vaccine that can be delivered broadly to those who are most susceptible to the risks of these diseases,” said Chen. “This is something that can help serve the most vulnerable populations in low resource settings in sub-Sahara Africa and South Asia, where the disease burden is highest.”

Development of the vaccine has been years in the making. Ultimately, it will be comprised of several weakened strains of Shigella, expressing a wide array of ETEC antigens, enabling the body’s immune system to generate antibodies and cellular protection against these diarrheal pathogens. Researchers at CVD, including Barry, have been constructing optimized vaccine components and analyzing their performance in preclinical studies to develop the best form of protection. Development of additional vaccine components will be supported by this partnership with Emergent.

Development of this vaccine was based on epidemiologic studies that identified the most important strains and antigens associated with disease and included extensive genome analysis and pre-clinical testing,” said Barry. According to the World Health Organization (WHO), Shigella and ETEC are two of the leading causes of diarrhea worldwide. It is estimated that these two bacteria alone are responsible for more than 15 percent of the approximately 500,000 deaths among children under the age of 5.

“One of the ways Emergent furthers its mission – to protect and enhance life – is to invest in scientific research and development by organizations that are aligned with our focus on improving public health,” said Kelly Lyn Warfield, PhD, vice president of vaccines research and development at Emergent BioSolutions. “As a leader in emerging infectious diseases and travel health vaccines, we are pleased to partner with USOM to advance a potential vaccine to protect against Shigella and ETEC, two leading causes of diarrhea worldwide.”

In addition to the risk of child mortality, CVD research has shown that repeated infections and episodes of diarrheal diseases can lead to stunted growth in young children and impaired physical and cognitive development. Individuals typically contract Shigella and ETEC infection by ingesting contaminated food and water, but these illnesses can also be contracted through close direct contact with others who are infected.

“We know that diarrheal diseases are a leading cause of mortality for children. This research at the Center for Vaccine Development and Global Health is a critical step in helping to protect the most vulnerable children world-wide. Our expertise in clinical trials will help set the stage toward final delivery of an important vaccine that could impact millions,” said Kathleen Neuzil, MD, MPH, the Myron M. Levine Professor in Vaccinology, professor of medicine and pediatrics, and director of the CVD.

Diarrheal diseases can typically be treated through rehydration therapy and with antibiotics for travelers to countries and regions where there is a high prevalence. However, many who are exposed to these pathogens -- children under the age of five and others in low resource settings -- do not always have access to these treatments. A vaccine, when finally tested and approved, could offer broad protection.

“Diarrheal diseases are one of the biggest challenges in global health. Our researchers at the University of Maryland School of Medicine have developed critical tools to protect children and others in settings where there is high risk. This work not only tackles some of the most challenging diseases, but it will ultimately impact millions of people around the world,” said E. Albert Reece, MD, PhD, MBA, executive vice president for medical affairs at UM Baltimore, and the John Z. and Akiko K. Bowers Distinguished Professor and Dean of the University of Maryland School of Medicine.

Source: University of Maryland School of Medicine