The Pathology of Malignant Catarrhal Fever, With an Emphasis on Ovine Herpesvirus 2

Abstract

The enigmatic pathogenesis of malignant catarrhal fever (MCF) involves dysregulated immune responses in susceptible ruminant species. Economically important outbreaks of MCF are due to 2 of the 10 viruses currently comprising the malignant catarrhal fever virus group: ovine herpesvirus 2 (OvHV-2) and alcelaphine herpesvirus 1 (AlHV-1). Attempts to develop effective vaccines for this group of viruses in the 1970s were sufficiently discouraging that they were temporarily abandoned. This review focuses on recent efforts to understand the pathogenesis of MCF, particularly the sheep-associated form of the disease, with the goal of developing rational control methods, including vaccination. The past 2 decades have seen several advances, including recognition of new members of the MCF virus group, better diagnostic assays, induction of disease by a natural route (aerosol), and clearer understanding of OvHV-2's shedding patterns by domestic sheep. A consistent theme in experimental studies of OvHV-2 in susceptible species is that there are 2 peaks of OvHV-2 gene expression: a preclinical peak involving the respiratory tract and a second in multiple organ systems leading to clinical disease. Latent and lytic gene expression may coexist in tissues during clinical stages in symptomatic animals.Keywords bison, cattle, malignant catarrhal fever, ovine herpesvirus 2, sheep, virus, alcelaphine herpesvirus 1, vasculitisIn 1997, we were approached by a bison producer who lost multiple adult animals to malignant catarrhal fever (MCF). 132As is often the case, the producer's questions were pragmatic and dealt with the likely source of infection, how the outbreak might be stopped, and whether effective treatment or vaccination was possible. At that time, our group had worked on MCF for several years, relying in part on case material from natural outbreaks of MCF in domestic cattle. 92,93 Diagnosticians and researchers were the beneficiaries of new diagnostic assays to confirm infection in live animals. 4,70 Unfortunately, the news for the producer was bad. The source of infection was probably domestic sheep, but the distance over which transmission was likely to occur was unknown. The producer reported that no sheep were in the immediate vicinity of her herd. Little was known about how sheep shed the virus or the duration of shedding. Since MCF was of modest interest to the cattle industry, funding for basic studies was constrained. No effective treatment existed. In the wake of that owner's outbreak, it quickly became clear that MCF was of appreciable importance to the commercial bison industry in the United States and Canada. 7,94 The long history and intriguing nature of MCF (Table 1) were small solace to the Colorado producer in the absence of practical solutions from MCF researchers. A total of 27 bison died as a result of the outbreak. Three bison remaining in the herd were butchered. Efforts to raise bison on the property were temporarily abandoned.This review summarizes recent progress in our understanding of sheep-...

Potential Pathogenetic Role of Bovine Herpesvirus 4 in Two Dairy Cows with Dermatitis-Pyrexia-Hemorrhagic Syndrome

“…Although the pathogenesis of vasculitis remains unsolved, it is usually assumed that a small fraction of infected lymphocytes induces the proliferation and deregulation of uninfected cells with a nonspecific cytotoxic effect (19). In the present cases, both electron microscopy and viral culture of skin samples were negative, consistent with previous observations in cases of cutaneous MCF, in which viral particle detection and viral antigen expression in skin samples may be limited (19).…”

“…Although the pathogenesis of vasculitis remains unsolved, it is usually assumed that a small fraction of infected lymphocytes induces the proliferation and deregulation of uninfected cells with a nonspecific cytotoxic effect (19). In the present cases, both electron microscopy and viral culture of skin samples were negative, consistent with previous observations in cases of cutaneous MCF, in which viral particle detection and viral antigen expression in skin samples may be limited (19). Furthermore, BoHV-4 has been isolated from cattle with a variety of inflammatory lesions, such as mammary pustular dermatitis, metritis, pneumonia, diarrhea, respiratory infections, interdigital dermatitis, and vaginitis (20)(21)(22)(23).…”

Herpesviral infections of farm and companion animals

“…Śmiertelność wynosi od 50% do 70%, zakażone zwierzęta zwykle padają w ciągu 48 godzin od wystąpienia pierwszych objawów (69,95). U świń wirus może powodować zapalenie opon mózgowo-rdzeniowych, a także wywoływać ronienia (66).…”

Ovine Herpesvirus 2 Glycoproteins B, H, and L Are Sufficient for, and Viral Glycoprotein Ov8 Can Enhance, Cell-Cell Membrane Fusion

“…vasculitis (2). In vivo, the virus has tropism for at least two cell types, CD8 ϩ T cells and epithelial cells, specifically alveolar type II epithelial cells in sheep lungs (3,4).…”