Navy Researchers and Collaborators Testing a Vaccine for Traveler's Diarrhea

By Doris Ryan, Naval Medical Research Center Public Affairs

SILVER SPRING, Md. (NNS) -- A vaccine to protect against Campylobacter jejuni was recently approved for human clinical trials by the Food and Drug Administration.

Researchers at the Naval Medical Research Center (NMRC) began an FDA approved phase 1 clinical trial for a C. jejuni vaccine at the Walter Reed Army Research Institute Clinical Trials Center in April. C. jejuni is a global health problem and is a leading cause of diarrhea in deployed military personnel and international travelers.

Dr. Patricia Guerry, a senior scientist at NMRC, was one of the first molecular microbiologists to address the health concerns of Campylobacter in the 1980s, a decade after it was first discovered and recognized as a cause of human diseases. Teaming up with Dr. Mario Monteiro, from the University of Guelph in Ontario, Canada, Guerry oversaw the design and development of a prototype C. jejuni vaccine.

"Work on conjugate vaccines against C. jejuni started in 2004 and the initial studies were done in parallel with other vaccine approaches," said Guerry. "These initial promising studies demonstrated immunogenicity in mice. A prototype vaccine is being used in this clinical trial with the primary aim of evaluating the safety of this vaccine and immune responses."

This phase 1 study will enroll up to 48 healthy volunteers to determine safety and dosing levels. Cmdr. Robert Gormley is leading the study.

"We are vaccinating up to 48 volunteers with an injection to the upper arm," Gormley said. "Since this is a dose escalation study, we are vaccinating sixteen volunteers with a low dose before subsequently vaccinating an additional two groups of sixteen each at higher doses. It is hoped that at the end of the study, the results will allow the research team to take the vaccine into a phase 2 study where volunteers will be vaccinated to see if it protects against Campylobacter in a human challenge study."

He added that the emerging epidemiology and understanding of campylobacter-attributed burden in military personnel, travelers and global populations combined with the promising development of the Campylobacter vaccine may lead to wider interest in the development of a vaccine against this disease.

Diarrhea has historically been a substantial cause of morbidity for deployed U.S. military personnel and continues to the present day.

The NMRC Enteric Diseases Department's research program is centered on the development of effective countermeasures to prevent or abate bacterial diarrhea, with most efforts aimed at vaccine research and development. NMRC researchers have identified many surface structures of the bacteria, found how it invades human cells, and characterized many aspects of the immune response. This work continues with the use of comparative genomics, expression arrays, and studies to try to better understand the protective immune response, all of which will enable researchers to develop an effective vaccine.