Ovine progressive pneumonia See Visna maedi virus

Ovine pulmonary adenocarcinoma virus (OPAV) A species in the genus Betaretrovirus. Infects mainly domestic sheep worldwide except for Australasia. Causes a contagious, slow progressive lung disease which pathologically appears as an adenomatosis. There are multiple pulmonary adenocarcinomas which sometimes metastasize. There are similarities to human bronchoalveolar cell carcinomas. The disease develops slowly and is most common in the third year of life. Animal signs are respiratory distress, loss of appetite and coughing. Lambs less than 6 months may die in a few days, but in older sheep the disease is chronic, lasting months to years. Secondary infections, e.g. Pasteurella, are frequent complications. In the terminal stages there is copious secretion of tracheobronchial fluid. The virus has not been cultivated in cell culture; it can be transmitted to goats but is not endemic in that species. The disease can be transmitted by a cell-free filtrate or tumor extracts containing reverse transcriptase activity associated with particles which have a buoyant density typical of Retroviridae, and have been called jaagsiekte retrovirus (JSRV). The viral nucleic acid is distinct from that of maedi virus, and has been found endogenously in the genome of sheep, present as 15-20 copies per cell. Recent evidence suggests that the disease is transmitted specifically by an exogenous form of the virus that can be found in the tumors and lung secretions, and is probably not due to the endogenous virus-related sequences. The disease has been eradicated from Iceland by a slaughter policy. No vaccine is available. Synonyms: jaagsiekte virus; Lungers virus; sheep pulmonary adenomatosis virus.

Martin WB et al (1976) Nature 281, 183 Palmarini M et al (1996) J Virol 70, 1618 Palmarini M et al (2000) J Virol 74, 5776 Sharp JM et al (1986) Vet Rec 119, 245

ovine respiratory syncytial virus Isolates of respiratory syncytial virus have been made from sheep which appear to be distinct from the human or bovine viruses, but little is known of the clinical characteristics or significance of natural infection with this virus.

owl hepatosplenitis herpesvirus Synonym for strigid herpesvirus 1.

owl monkey herpesvirus Synonym for cebine herpesvirus 1 and 2.

owl's eye intranuclear inclusions Characteristic large inclusion bodies seen in the nucleus of cells infected with cytomegaloviruses.

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