Malignant Catarrhal Fever in Cattle in the Irkutsk Region

Clinical, pathological, and molecular aspects of malignant catarrhal fever in Russia: a case report

Malignant catarrhal fever (MCF) is a highly fatal viral disease caused by ovine gammaherpesvirus-2 (OvHV-2) that primarily affects cattle around the world. Sheep act as asymptomatic carriers, silently perpetuating the virus. Despite its global presence, MCF remains poorly understood in Russia due to limited surveillance, voluntary disease reporting, and its exclusion from routine differential diagnoses. This study aimed to investigate a suspected case of MCF in a Yakut-breed cow on a private farm in Pskov Oblast, Russia, bordering Estonia. The cow resided in a mixed sheep and cattle herd with direct sheep contact. Clinical examination and histological analysis revealed characteristic MCF lesions. Phylogenetic analysis of the cow's OvHV-2 revealed a mosaic structure. The polymerase01, gene clustered with strains from the Netherlands and Germany, while the tegument gene grouped with isolates from India and Egypt. This highlights the global nature of OvHV-2 genetic diversity. Overall, this study provides the first documented case of MCF in Russia and underscores the sporadic nature of the disease in cattle. The identification of novel pathological changes and the unique viral genetic makeup necessitate further investigation of MCF in Russia.

Viral contamination in cell culture: analyzing the impact of Epstein Barr virus and Ovine Herpesvirus 2

Cell culture techniques are increasingly favored over animal models due to rising costs, time constraints, and ethical concerns regarding animal use. These techniques serve critical roles in disease modeling, drug screening, drug discovery, and toxicity analysis. Notably, cell cultures facilitate primary virus isolation, infectivity assays, biochemical studies, and vaccine production. However, viral contamination in cell cultures poses significant challenges, particularly due to the necessity for complex and sophisticated detection methods. Among the prevalent viruses, Epstein Barr virus (EBV) is ubiquitous across human populations, infecting approximately 98% of individuals. Despite its prevalence, the detection of EBV is often not considered a safety priority, as its detection methods are well-established, including PCR assays that can identify both active and latent forms of the virus. Conversely, ovine herpesvirus 2 (OvHV-2), a relative of EBV, presents a critical concern due to its ability to infect a wide range of organs and species, including over 33 animal species and nearly all domestic sheep. This makes the detection of OvHV-2 crucial for the safety of cell cultures across various species. The literature reveals a gap in the comprehensive understanding of both EBV and OvHv-2 detection in cell culture systems, highlighting an urgent need for developing robust detection methodologies specific to EBV and OvHv-2 to ensure bioprocess safety.

First Molecular Evidence and Genetic Characterization of Ovine Herpesvirus 2 in Multiple Animal Species in India

Ovine herpesvirus 2 (OvHV-2) is the causative agent of sheep-associated malignant catarrhal fever (SA-MCF), a highly fatal disease syndrome that predominantly affects susceptible hosts of the order Artiodactyla. In this study, an in-depth clinico-molecular investigation of SA-MCF disease in a morbid 50-days-old cattle calf (Bos taurus indicus) and asymptomatic infection in the in-contact reservoir hosts, sheep (Ovis aries), and goat (Capra hircus) housed on a farm located in the Southern India is reported. An OIE recommended SA-MCF type-specific PCR confirmed the etiological agent as OvHV-2. The genetic characterization and phylogenetic analyses based on the glycoprotein B (gB) gene indicate that three genetic variants of OvHV-2 had infected the animal cluster of this study. As the OvHV-2 infection eventually lead to the death of the cattle calf, and the fact that its gB sequence carried four unique amino acid substitutions (N169S, L594P, I645V, and V730A), an investigation of these substitutions impact on its stability and molecular flexibility was carried out. The mapping of these amino acid substitutions on the three-dimensional structure of gB coupled with supplementary investigations showed that these substitutions conveyed the molecular flexibility to the gB, at the cost of its stability. Future studies would be to investigate whether these gB substitutions have any impact on membrane fusion activity using a virus-free cell-to-cell membrane fusion assay. The study also highlights the importance of adopting stringent biosecurity measures where mixed animal farming is a common practice.