Small ruminant lentivirus-induced arthritis: clinicopathologic findings in sheep infected by a highly replicative SRLV B2 genotype.
We describe the clinicopathologic features of an arthritis outbreak in sheep induced by small ruminant lentivirus (SRLV), linked to the presence of a new SRLV isolate phylogenetically assigned to caprine arthritis encephalitis virus-like subgroup B2. Thirteen SRLV seropositive Rasa Aragonesa adult ewes were selected from 5 SRLV highly infected flocks (mean seroprevalence, 90.7%) for presenting uni- or bilateral chronic arthritis in the carpal joint. A complete study was performed, including symptomatology, histopathology, immunocytochemistry, immunohistochemistry, in situ hybridization, and microbiology. The carpus was the joint almost exclusively affected, with 10 sheep (76%) showing a moderate increase in carpal joint size (diameter range, 18-20 cm; normal range, 15-16 cm) without signs of locomotion problems and with 3 ewes (23%) showing severe inflammation with marked increase in diameter (21-24 cm), pain at palpation, and abnormal standing position. Grossly, chronic proliferative arthritis was observed in affected joints characterized by an increased thickness of the synovial capsule and synovial membrane proliferation. Microscopically, synovial membrane inflammation and proliferation and hyperplasia of synoviocytes were observed. More positive cases of SLRV infection were detected by immunocytochemistry of articular fluid than of bronchoalveolar lavage fluid. Immunohistochemistry and in situ hybridization also detected positive cells in the subsynovial connective tissue, lung, mediastinal lymph node, mammary gland, and mammary lymph node. All animals were negative for the presence of Mycoplasma or other bacteria in the articular space. The present outbreak likely represents an adaptation of a caprine virus to sheep. Our results underline the importance of the arthritis induced by SRLV in sheep, a clinical form that might be underestimated.
Department of Anatomy, Embryology and Genetics, University of Zaragoza, Zaragoza, Spain Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain.
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Pérez
Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain.
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Biescas
Institute of Agrobiotechnology, CSIC-Public University of Navarra-Government of Navarra, Navarra, Spain.
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Reina
Institute of Agrobiotechnology, CSIC-Public University of Navarra-Government of Navarra, Navarra, Spain.
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Glaria
Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain Carnes Oviaragón SCL, Zaragoza, Spain.
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Marín
Carnes Oviaragón SCL, Zaragoza, Spain.
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A
Marquina
Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain.
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E
Salazar
Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain.
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Álvarez
Institute of Agrobiotechnology, CSIC-Public University of Navarra-Government of Navarra, Navarra, Spain.
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de Andrés
Carnes Oviaragón SCL, Zaragoza, Spain.
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Fantova
Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain.
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Badiola
Institute of Agrobiotechnology, CSIC-Public University of Navarra-Government of Navarra, Navarra, Spain.
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Amorena
Department of Animal Pathology, University of Zaragoza, Zaragoza, Spain Lluis.Lujan@unizar.es.
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Luján
D000818:Animals; D001168:Arthritis / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D016088:Arthritis-Encephalitis Virus, Caprine / Q000235:genetics / Q000502:physiology; D005838:Genotype; D016086:Lentivirus / Q000235:genetics / Q000502:physiology*; D016180:Lentivirus Infections / Q000473:pathology / Q000662:veterinary* / Q000821:virology; D010802:Phylogeny; D016036:Seroepidemiologic Studies; D012756:Sheep; D012757:Sheep Diseases / Q000473:pathology* / Q000821:virology; D013045:Species Specificity; D013583:Synovial Membrane / Q000821:virology
Visna-Maedi virus; arthritis; caprine arthritis encephalitis virus; joint; lentivirus; ovine progressive pneumonia; sheep; small ruminant lentivirus