"Visna virus (also known as visna-maedi virus, maedi-visna virus and ovine lentivirus) from the genus lentivirinae and subfamily Orthoretrovirinae, is a \"prototype\" retrovirus that causes encephalitis and chronic pneumonitis in sheep. It is known as visna when found in the brain, and maedi when infecting the lungs."@en . . "violet"@en . . .