Borna virus. Coloured Transmission Electron Micro- graph of a Borna virus in a tissue culture. The virus causes the fatal Borna disease in horses and may be a cause of human psychiatric diseases such as clinical depression & schizophrenia. The virus has an outer membrane (envelope, blue). This encloses the genetic material (purple) which is comprised of Ribonucleic Acid (RNA). Borna infects a wide range of creatures, including humans. It infiltrates the nervous system, being particularly found in parts of the brain, such as the hippocam- pus and hypothalamus, which control emotions and desires. Drugs to treat Borna may cure psychiatric diseases. Magnification: x180,000 at 6x4.5cm size.