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A new conjugate vaccine containing the capsule polysaccharides from two strains of Campylobacter jejuni, a major cause of bacterial diarrhea worldwide, provided protection against infection in mice and monkeys and may ultimately have human implications. The researchers from the University of Guelph, Ontario, Canada, the Naval Medical Research Center, Silver Spring, Maryland and the Naval Medical Research Center Detachment, Lima, Peru report their findings in the March 2009 issue of the journal Infection and Immunity.
C. jejuni infection is the leading cause of diarrheal disease in the U.S. as well as some developing countries and is also associated with reactive arthritis, irritable bowel syndrome, and Guillain Barre syndrome (GBS) which occurs when the body's immune system attacks part of the peripheral nervous system. Due to several hurdles in the research process, mainly the association of C. jejuni with GBS and that C. jejuni has proven to be unresponsive to studies on molecular pathogenesis, no licensed vaccines are currently available.
The capsule polysaccharide (CPS) of C. jejuni is one of the few virulence factors that have been identified. Due to the success of CPS conjugate vaccines against other mucosal pathogens the researchers in this study used CPSs from two strains of C. jejuni (81-176 and CG8486) to develop a vaccine and tested its effectiveness in mice and monkeys challenged with C. jejuni infection. Following subcutaneous vaccination mice demonstrated significant immune response and reduction in disease. The CPS 81-176 vaccine elicited 100 percent protection against diarrhea in the New World monkey, Aotus nancymaae.
"The C. jejuni CPS conjugate vaccines synthesized in this study were immunogenic in mice and reduced the diseases following intranasal challenge with the homologous strain of C. jejuni," say the researchers. "We also show here that the 81-176 CPS conjugate vaccine is immunogenic and 100 percent protective against diarrheal disease in New World monkeys."
Reference: M.A. Monteiro, S. Baqar, E.R. Hall, Y. Chen, C.K. Porter, D.E. Bentzel, L. Applebee, P. Guerry. 2009. Capsule polysaccharide conjugate vaccine against diarrheal disease caused by Campylobacter jejuni. Infection and Immunity, 77. 3: 1128-1136.