A team of scientists from the United States and Canada has created a first-ever carbohydrate-based vaccine against Clostridium bolteae, gut bacterium common in autistic children.

Clostridium bolteae was discovered in 2003. It is known to play a role in gastrointestinal disorders, and it often shows up in higher numbers in the gastrointestinal tracts of autistic children than in those of healthy kids. More than 90 per cent of children with autism spectrum disorders suffer from chronic, severe gastrointestinal symptoms. Of those, about 75 per cent suffer from diarrhea.

“Little is known about the factors that predispose autistic children to C. bolteae. Although most infections are handled by some antibiotics, a vaccine would improve current treatment,” said Dr Mario Monteiroa of the University of Guelph, Canada, senior author of a paper published in the journal Vaccine.

“This is the first vaccine designed to control constipation and diarrhea potentially caused by C. bolteae and perhaps control autism-related symptoms associated with this microbe.”

Autism cases have increased almost sixfold over the past 20 years, and scientists don’t know why. Although many experts point to environmental factors, others have focused on the human gut. Some researchers believe toxins and/or metabolites produced by gut bacteria, including C. bolteae, may be associated with symptoms and severity of autism, especially regressive autism.

The new anti-C. bolteae vaccine targets the specific complex polysaccharides, or carbohydrates, on the surface of the bug.

“The vaccine effectively raised C. bolteae-specific antibodies in rabbits. Doctors could also use the vaccine-induced antibodies to quickly detect the bug in a clinical setting,” Dr Monteiro said.

“The vaccine might take more than 10 years to work through preclinical and human trials, and it may take even longer before a drug is ready for market. But this is a significant first step in the design of a multivalent vaccine against several autism-related gut bacteria.”

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Bibliographic information: Brittany Pequegnat et al. A vaccine and diagnostic target for Clostridium bolteae, an autism-associated bacterium. Vaccine, published online April 18, 2013; doi: 10.1016/j.vaccine.2013.04.018