Visna virus, (also known as Visna-Maedi virus, Maedi-Visna virus or 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. Life-long, persistent infections in sheep occur in the lungs, lymph nodes, spleen, joints, central nervous system, and mammary glands;...
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Visna virus, (also known as Visna-Maedi virus, Maedi-Visna virus or 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. Life-long, persistent infections in sheep occur in the lungs, lymph nodes, spleen, joints, central nervous system, and mammary glands; The condition is sometimes known as "ovine progressive pneumonia", particularly in the United States, or "Montana Sheep Disease". White blood cells of the monocyte/macrophage lineage are the main target of Visna virus.
First described in 1954 by Bjorn Sigurdsson in Iceland, Maedi-Visna virus was the first lentivirus to be isolated and characterized, accomplished in 1957 by Sigurdsson. "Maedi", Icelandic for dyspnoea, and "visna", Icelandic for "wasting" or "shrinking" of the spinal cord, refer to endemic sheep herd conditions that were only...
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