lunes, 19 de mayo de 2014
FDA Approves Campylobacter jejuni Vaccine for Human Trials
The vaccine is a conjugate containing polysaccharides from C. jejuni joined to a protein
Campylobacter is a major cause of bacterial diarrhea worldwide — estimated to be the cause of 4-15 percent of cases. It’s a problem in both developed and developing countries and is associated with unpasteurized dairy products, contaminated water, poultry and produce.
In the U.S., the Centers for Disease Control and Prevention estimates that campylobacteriosis affects more than 1.3 million people every year.
Although Campylobacter infections are generally mild but severe complications can include reactive arthritis and neurological disorders such as Guillain-Barré syndrome.
Campylobacter is one of a select group of pathogens that produces a polysaccharide capsule — or sugar coating on the surface, which is kind of a protective layer. So the vaccine is a conjugate containing polysaccharides from C. jejuni joined to a protein to enhance its immunogenicity. The idea is it can generate antibodies against the polysaccharide capsule to cause bacterial lysis.
There are a number of polysaccharides conjugate vaccines on the market today. Prevnar for pneumococcal pneumonia is one of the best-known examples. They have been very successful for pneumococcal infections, but Campylobacter is unusual for an enteric pathogen in that it also expresses the polysaccharide capsule. There are currently no licensed vaccines for Campylobacter, but NMRC has tested two others that it ultimately did not develop past Phase I.
This latest vaccine is currently in Phase I testing where it’s being tested for safety and immunogenicity. The previous ones passed in terms of safety, but they weren’t particularly immunogenic. If the current vaccine passes into Phase IIB we would immunize other volunteers to select the best dose and then challenge them with a strain of Campylobacter jejuni to see if it protects against diarrhea.
The military is interested in this vaccine because troops are a certain sub-class of travelers, but it could also be marketed to civilian travelers going to endemic areas.