Viral neurotropism, peripheral neuropathy and other morphological abnormalities in bovine ephemeral fever virus‐infected downer cattle

Abstract

The data confirmed neurotropism of BEFV in cattle and documented histomorphological abnormalities in peripheral nerves and brain which, together with spinal cord lesions, may contribute to chronic paralysis in BEFV-infected downer cattle.

Post‐viraemic detection of bovine ephemeral fever virus by use of autogenous lymphoid tissue‐derived bovine primary cell cultures

“…9 For the next 7 days, the steer remained paralysed and recumbent, warranting euthanasia, which was done by intravenous infusion of 60 mL of pentobarbitone sodium (Lethabarb Euthanasia Injection, Virbac, NSW, Aust) in accordance with the ethical guidelines (Charles Darwin University Animal Ethics Committee permit no. A confirmatory BEF diagnosis was made on the basis of a positive qRT-PCR result (cycle threshold (Ct) value ≤ 45.0 = positive; Ct value > 45.0 = negative) on jugular blood supported by characteristic clinical symptoms that included a fever (rectal temperature 39.2 C), recumbence, anorexia and serous oculonasal discharges.…”

“…Samples of peripheral blood collected over the course of the 1-week illness, fresh tissues and pericardial, thoracic, peritoneal and synovial fluids taken during necropsy examination were tested by qRT-PCR using a recently described protocol, 9 based on a previously standardised method. 10 Aseptically collected fresh spleen and haemal node samples for virus isolation were placed into sterile Gibco® Medium 199 (Life Technologies, NY, USA).…”

“…9 The immunoperoxidase assay for demonstrating BEFV antigens was based on a Dako EnVision + System-HRP kit (Dako Australia Pty Ltd, VIC, Aust) with a few modifications and used the mouse monoclonal antibody (mAb) DB5 as the primary antibody probe. In addition, 4-μm sections of the spleen, haemal node and other tissues were also tested.…”

“…8 On the basis of their observation, the authors of that report proposed that bone marrow was a potential site of virus replication even though a specific host cell type that could support such replication was never defined. 9 The largely intracytoplasmic viral antigens were seen in different cells, including but not limited to neutrophils, macrophages, spindle-shaped cells of perivascular location presumed to be pericytes and Schwann cells of peripheral nerve tissue. 9 The largely intracytoplasmic viral antigens were seen in different cells, including but not limited to neutrophils, macrophages, spindle-shaped cells of perivascular location presumed to be pericytes and Schwann cells of peripheral nerve tissue.…”

“…8 Most recently, we used immunohistochemistry (IHC) and quantitative reverse transcription-PCR (qRT-PCR) assays to detect BEFV antigens and RNA in postmortem tissue specimens collected from adult cattle several weeks after cessation of viraemia. 9 Although these findings have elucidated the tissue tropism of the virus in cattle, the specific cell types that support virus replication remain to be definitively identified. 9 Although these findings have elucidated the tissue tropism of the virus in cattle, the specific cell types that support virus replication remain to be definitively identified.…”