“A single viral protein causes behavioural changes in mice similar to those experienced by people with mental illness, reveals a study by Japanese researchers.

The effects of the protein, produced by a common pathogen called the Borna disease virus (BDV), may help scientists understand how viruses could contribute to psychiatric disease in humans.” New Scientist

In humans, evidence of infection with BDV is found in a vastly higher proportion of severely mood-disordered individuals than healthy controls. A ‘hit’ by being infected with BDV at crucial stages of CNS development appears necessary for the behavioral consequences. BDV affects not the neurons themselves but their support cells, the glia, disruption of whose functions disturb normal neural connectivity. That being said, it is a stretch to say that the behavioral changes seen in the mice in this study, in which a gene for a BDV protein was inserted into the genome and expressed in the mice’s CNS, are an analogue of human mental illness. All that can be said is that they produce generic behavioral changes. They are not a model for any specific human psychiatric disease, which is perhaps fitting, because no one can yet figure out with which human psychiatric disease BDV is supposed to be associated.