Scientists have long suspected that an enigmatic pathogen called the Borna virus plays a role in some neuropsychiatric disorders. Now, they have for the first time isolated the virus from a schizophrenic patient's brain. But some researchers caution that the finding may not be real.
The Borna Disease Virus (BDV) causes neurological disorders in horses, sheep, and other animals in Central Europe. Traces of the virus have also been found in livestock elsewhere, strangely without any signs of the disease. In the early 1980s, scientists found that patients suffering from schizophrenia and manic depression were up to 10 times more likely to have antibodies to the virus than healthy people, suggesting that infection might contribute to those diseases. Later, the virus's genetic material turned up in patients, and in 1996, a German team isolated live virus from psychiatric patients' blood cells. But so far, it had never been found where it might cause psychiatric problems: in the brain.
When a team of Japanese scientists, in collaboration with Juan Carlos de la Torre of the Scripps Research Institute in La Jolla, California, performed an autopsy on a schizophrenic patient who had tested positive for Borna antibodies, they initially found both viral RNA and viral proteins in certain areas of his brain, but no live virus. After they injected a small amount of minced brain tissue into the brains of gerbils, however--which are very prone to BDV infection--the virus started multiplying, and they could isolate and culture live virus from the animals' brains.
Liv Bode, a virologist at the Robert Koch Institut in Berlin whose team was the first to isolate the virus from patients, welcomes the findings as a "solid piece of work that fits the picture and lends further support to the existence of human [strains of] BDV."
Others aren't so sure. Last December, Peter Stäheli and his team at the University of Freiburg, Germany, reported that most of the human isolates found so far were most closely related to the strains used in the labs that had found them--suggesting the findings had been artifacts, caused by contamination. The same could have happened here, says Stäheli.
Researchers still have no idea how Borna would cause disease. But if it does, that would have huge consequences for our understanding of mental illness, says Norbert Nowotny of the University of Veterinary Sciences in Vienna. To settle the debate, he says, "we need an independent confirmation of all these isolates."