Bluetongue virus (Reoviridae; Orbivirus, BTV), which is usually transmitted by biting midges, affects wild and domestic ruminants worldwide, thereby causing an economically important disease. Recently, a putative new BTV strain was isolated from contaminated vaccine batches. In this study, we investigated the genomic and clinical characteristics of this isolate, provisionally designated BTV‐28. Phylogenetic analysis of BTV‐28 segment 2 (Seg‐2) showed that it is related to Seg‐2 from BTV serotypes 4, 10, 11, 17, 20 and 24, sharing 64%–66% identity in nucleotide sequences (nt) and 59%–62% in amino acid (aa) sequences of BTV VP2. BTV‐28 Seg‐6 is related to the newly reported XJ1407 BTV isolate, sharing 76.70% nt and 90.87% aa sequence identity. Seg‐5 was most closely related to a South African BTV‐4 strain, and all other segments showed close similarity to BTV‐26. Experimental infection by injection of 6‐month‐old ewes caused clinical signs in all injected animals, lasting from 2 to 3 days to several weeks post‐infection, including high body temperature, conjunctivitis, nasal discharge and rhinitis, facial oedema, oral hyperaemia, coronitis, cough, depression and tongue cyanosis. Naïve control animals, placed together with the infected sheep, displayed clinical signs and were positive for viral RNA, but their acute disease phase was shorter than that of BTV‐injected ewes. Control animals that were kept in a separated pen did not display any clinical signs and were negative for viral RNA presence throughout the experiment. Seroconversion was observed in the injected and in one of the two contact‐infected animals. These findings demonstrate that BTV‐28 infection of sheep can result in clinical manifestation, and the clinical signs detected in the contact animals suggest that it might be directly transmitted between the mammalian hosts.
In September 2015, a large outbreak caused by epizootic hemorrhagic disease virus (EHDV) was identified in Israeli dairy and beef farms. The main clinical signs were reduced milk production, weakness, drooling, lameness and recumbency, fever, slight erythema of nasal and oral mucosae, weight loss, and abortion. Dyspnea, cachexia, and death were observed less frequently. The clinical diagnosis was confirmed by ELISAs and EHDV-specific real-time reverse transcription PCR (RT-rtPCR), followed by conventional RT-PCR of the VP2 gene and sequence analysis. According to the sequence and phylogenetic analysis of theVP2 gene, the 2015 Israeli EHD outbreak was caused by EHDV-6, which was found not only in clinically ill cattle, but also in aborted fetuses.
Summary The insect‐transmitted Shuni virus (SHUV) belongs to the Simbu serogroup of orthobunyaviruses and it is known to induce abortions, stillbirths and severe congenital malformations in ruminants and may cause neurological signs in infected horses. Here, SHUV was detected in brain samples of two Israeli cattle, which suffered from severe neurological signs that led to the deaths of the animals. During histopathological examination of the first case, a 5‐month‐old calf, small perivascular cuffs, composed mainly of neutrophils with few lymphocytes were observed in the brain stem and cerebrum. Similar infiltrates were also found to a lesser extent in the cerebellar meninges leading to the diagnosis of acute‐subacute meningoencephalitis. The histological examination of the brainstem from the second case, a 16‐month‐old heifer, revealed perivascular infiltration composed of equal numbers of macrophages and neutrophils associated with cerebral and meningeal haemorrhages. In this case encephalitis was diagnosed. Viral RNA was extracted from brain samples of both cattle that suffered from severe neurological signs and was subsequently tested by a polymerase chain reaction PCR assay specific for Simbu serogroup viruses and found positive. The presence of SHUV was subsequently confirmed by the isolation of the virus from one sample and sequence analysis of both brain samples. The comparison of the complete sequences of the coding regions of all three genome segments from both cases revealed a close relationship to Shuni viruses detected in tissue samples of aborted or malformed calves or lambs born during the last years in Israel.
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