A recent study shows that activating a woman’s immune system during pregnancy interferes with the development of neural cells in the brains of her offspring in a way that damages the cells’ ability to transmit signals and communicate with other cells. Results of the research, performed by scientists at Davis Center for Neuroscience and Department of Neurology, may suggest how maternal viral infections increase the risk for having a child with schizophrenia or autism spectrum disorder (ASD).

Kimberley McAllister, professor in the Center for Neuroscience and senior author of the study, and her team performed the study on mice and rats. They compared the brains of offspring whose mothers were exposed to viruses with the brains of rodent offspring where the mother’s immune system had not been activated. Offspring whose mothers were exposed to viruses showed much higher brain levels of immune molecules known as the major histocompatibility complex I (MHCI) molecules.

The study, published in the Journal of Neuroscience, found these high MHCI levels impaired the ability of the neurons from the newborn mice’s brains to form synapses, tiny gaps between brain cells that allow these cells to communicate. Previous research suggests these altered connections in the brain, especially in the cerebral cortex, may cause ASD and schizophrenia.

“This is the first evidence that neurons in the developing brain of newborn offspring are altered by maternal immune activation,” McAllister said. “Until now, very little has been known about how maternal immune activation leads to autism spectrum disorder and schizophrenia-like pathophysiology and behaviors in the offspring.”

McAllister and her team then reduced MHCI to normal levels and found synapse density returned to normal. “These results indicate that maternal immune activation does indeed alter connectivity during prenatal development, causing a profound deficit in the ability of cortical neurons to form synapses that are caused by changes in levels of MHCI on the neurons,” she said.

This research could someday help scientists develop diagnostic tests and therapies to improve the lives of individuals with these neuro-developmental disorders such as autism spectrum disorder and schizophrenia.


  • "UC Davis researchers find how viral infection disrupts neural development in offspring, increasing risk of autism." UC Davis Health System. 19 Sept 2013. Web. 8 Oct 2013.
  • Elmer BM, Estes ML, Barrow SL, McAllister AK. "MHCI Requires MEF2 Transcription Factors to Negatively Regulate Synapse Density during Development and in Disease." J Neurosci. 2013 Aug 21;33(34):13791-804.