Scientists have discovered that activating a chemical called IL-17a in pregnant mice alters brain structures in the developing fetus, and causes symptoms in baby mice similar to those of humans diagnosed with autism spectrum disorder (ASD).

When scientists blocked the cells that produce the chemical, either by shutting down the IL-17a gene or treating the pregnant mice with antibodies, normal brain structure was restored in the baby mice.

Previous studies had suggested a link between viral infections during pregnancy and the development of autism, and the researchers hope their study will lead to treating or curing the disorder.

According to the National Autism Foundation, autism affects 1 in 68 children and is a bio-neurological developmental disability. There is no cure.

The new study focused on T-cells, or T-lymphocytes, immune cells that are activated by invading viruses to fight them off. A subcategory of helper T-cells called Th17 cells, produces interleukin 17 (IL-17), a protein that increases the body's response to infections.

Scientists know that when the body produces too many T-lymphocytes, autoimmune diseases such as asthma can be triggered, but the new study found that IL-17a can also create behavioral abnormalities.

"Blocking the function of Th17 cells and IL-17a in the maternal womb by using antibodies and other genetic techniques completely restored normal behavior and brain structure in the affected offspring," said study co-author Jun R. Huh, Ph.D., of the University of Massachusetts Medical School.

"The study also showed that a therapeutic treatment with antibodies blocking IL-17a corrected certain behavioral abnormalities, suggesting Th17 cells, as well as the specific proteins they produce, may be candidate therapeutic targets in efforts to prevent autism in the children of susceptible mothers."

"To our knowledge, this is the first study to identify a specific population of immune cells that may have a direct role in causing behaviors linked to autism," said immunologist and study co-author Dan Littman, M.D., Ph.D. of NYU Langone Medical Center.

The study is published in the journal Science.