Virological and pathological findings in Bluetongue virus serotype 8 infected sheep

Abstract

Twenty-seven sheep of the four most common Swiss breeds and the English breed Poll Dorset were experimentally infected with a northern European field strain of bluetongue virus serotype 8 (BTV-8). Animals of all breeds eveloped clinical signs, viremia and pathological lesions, demonstrating that BTV-8 is fully capable of replicating and inducing bluetongue disease (BT) in the investigated sheep. Necropsy performed between 10 and 16 days post-infectionem (d.p.i.) revealed BT-typical hemorrhages, effusions, edema, erosions and activation of lymphatic tissues. Hemorrhages on the base of the Arteria pulmonalis and the left Musculus papillaris subauricularis were requently present. Histology confirmed the macroscopical findings. Using a score system, clinical manifestation and pathology were found to be significantly related. Furthermore, clinical signs and fever were shown to be indicative for the concurrent presence of high amounts of viral ribonucleic acid (RNA) in blood. Spleen, lung, lymph nodes and tonsils from all animals were analyzed regarding viral RNA loads and infectivity using real-time reverse transcriptase PCR (rRT-PCR) and virus isolation in cell culture, respectively. The highest amount of viral RNA was detected in spleen and lung and rRT-PCR revealed to be amore sensitive method for virus detection compared to virus isolation. KeywordsBluetongue virus serotype 8, sheep breed, clinicopathological picture, histology, virus detection, score system

Experimental oral infection of bluetongue virus serotype 8 in type I interferon receptor-deficient mice

“…The results showed that oral and intravenous infection of BTV-8 produce the same tissue lesions in IFNAR (2/2) mice (Calvo-Pinilla et al, 2009a), regardless of the mode of infection. In addition, these microscopic lesions are similar to those observed in the natural host (Maclachlan et al, 2009;Worwa et al, 2010). To confirm that BTV-8 replicates in these tissues, immunohistochemistry with a hyperimmune serum from a BTV-8-infected cow was performed as described by Sanchez-Cordon et al (2010).…”

“…No infectious virus was detected in the other tissues analysed. The same viral tropism has been observed in IFNAR (2/2) mice infected intravenously with BTV (Calvo-Pinilla et al, 2009a) and in naturally BTVinfected calves and sheep where high titres of BTV are present in lung, precapsular and mesenteric lymph nodes, thymus and spleen, which are secondary sites of BTV replication (Barratt-Boyes & MacLachlan, 1994, 1995Hemati et al, 2009;MacLachlan et al, 1990;SanchezCordon et al, 2010;Worwa et al, 2010).…”

“…BTV-8-infected cells were not found in these tissues (data not shown). These data suggest that, after oral infection, the infected cells migrate to the lymphoid tissues that have been described as the secondary sites of BTV replication (Barratt-Boyes & MacLachlan, 1994, 1995Hemati et al, 2009;MacLachlan et al, 1990;Sanchez-Cordon et al, 2010;Worwa et al, 2010).…”

Bluetongue Virus in wild ruminants in Europe: Concerns and facts, with a brief reference to bluetongue in cervids in Greece during the 2014 outbreak

“…Typical post-mortem pathological findings include oedema and haemorrhages in mesenteric lymph nodes, pulmonary oedema, pleural and pericardial effusions. Additionally, multiple spots of haemorrhages in the pulmonary artery, as well as limited necrosis of myocardium are the histopathological findings most frequently seen Worwa et al, 2010;MacLachlan, 2011).…”

The combination of abundance and infection rates of Culicoides sonorensis estimates risk of subsequent bluetongue virus infection of sentinel cattle on California dairy farms

“…Sentinel animals were seronegative and virus-free at the beginning of the study. Serum and whole blood were collected weekly from each animal to assay for BTV-specific antibodies and viral nucleic acid, using group-reactive competitive enzyme-linked immunosorbent assay (cELISA; VMRD Inc., Pullman, WA) and RT-qPCR, as previously described (Ortega et al, 2010;Mayo et al, 2010;Worwa et al, 2010;Mayo et al, 2011).…”