6 research outputs found

    Comparison of ovine herpesvirus 2 genomes isolated from domestic sheep (Ovis aries) and a clinically affected cow (Bos bovis)

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    The rhadinovirus Ovine herpesvirus 2 (OvHV-2) is the causative agent of sheep-associated malignant catarrhal fever. OvHV-2 primarily affects ruminants and has a worldwide distribution. In this study, a composite sequence of OvHV-2 genomic DNA isolated from nasal secretions of sheep experiencing virus-shedding episodes was determined and compared with the sequence of OvHV-2 DNA isolated from a lymphoblastoid cell line derived from a clinically affected cow. The study confirmed the OvHV-2 sequence information determined for the cell line-isolated DNA and showed no apparently significant changes in the OvHV-2 genome during passage through a clinically susceptible species with subsequent maintenance in vitro. Amino acid identity between the predicted open reading frames (ORFs) of the two genomes was 94–100 %, except for ORF73, which had an identity of 83 %. Polymorphism in ORF73 was due primarily to variability in the G/E-rich repetitive central region of the ORF

    Characterization of ovine herpesvirus 2-induced malignant catarrhal fever in rabbits

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    Malignant catarrhal fever (MCF) is a frequently fatal lymphoproliferative disease syndrome primarily of ruminant species, caused by gammaherpesviruses in the genus Macavirus. Ovine herpesvirus 2 (OvHV-2), carried by sheep, causes sheep-associated MCF worldwide, while Alcelaphine herpesvirus 1 (AlHV-1), carried by wildebeest, causes wildebeest-associated MCF, mainly in Africa. Diseases in rabbits can be induced by both viruses, which are clinically and pathologically similar; however, recent studies revealed different expression of viral genes associated with latency or lytic replication during clinical disease between the two viruses. In this study, we further characterized experimentally induced MCF in rabbits by nebulization with OvHV-2 from sheep nasal secretions to elucidate the course of viral replication, along with in vivo incorporation of 5-Bromo-2’-Deoxyuridine (BrdU), to evaluate lymphoproliferation. All six rabbits nebulized with OvHV-2 developed MCF between 24 and 29 days post infection. OvHV-2 DNA levels in peripheral blood leukocytes (PBL) remained undetectable during the incubation period and increased dramatically a few days before onset of clinical signs. During the clinical stage, we found that predominantly lytic gene expression was detected in PBL and tissues, and both T and B cells were proliferating. The data showed that the viral gene expression profile and lymphoproliferation in rabbits with OvHV-2 induced MCF were different from that in rabbits with AlHV-1 induced MCF, suggesting that OvHV-2 and AlHV-1 may play a different role in MCF pathogenesis
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