Project description:Some members of the gamma herpesvirus genus Macavirus are maintained in nature as subclinical infections in well-adapted ungulate hosts. Transmission of these viruses to poorly adapted hosts, such as American bison and cattle, can result in the frequently fatal disease malignant catarrhal fever (MCF). Based on phylogenetic analysis, the MCF viruses (MCFV) cluster into two subgroups corresponding to the reservoir hosts' subfamilies: Alcelaphinae/Hippotraginae and Caprinae. Antibody cross-reactivity among MCFVs has been demonstrated using techniques such as enzyme linked immunosorbent and immunofluorescence assays. However, minimal information is available as to whether virus neutralizing antibodies generated against one MCFV cross react with other members of the genus. This study tested the neutralizing activity of serum and plasma from select MCFV-infected reservoir hosts against alcelaphine herpesvirus 1 (AlHV-1) and ovine herpesvirus 2 (OvHV-2). Neutralizing antibody activity against AlHV-1 was detected in samples from infected hosts in the Alcelaphinae and Hippotraginae subfamilies, but not from hosts in the Caprinae subfamily. OvHV-2 neutralizing activity was demonstrated in samples from goats (Caprinae) but not from wildebeest (Alcelaphinae). These results show that neutralizing antibody cross reactivity is present to MCFVs within a virus subgroup but not between subgroups. This information is important for diagnosing infection with MCFVs and in the development of vaccines against MCF.
Project description:Alcelaphine herpesvirus 1 (AlHV-1) is a ?-herpesvirus (?-HV) carried asymptomatically by wildebeest. Upon cross-species transmission, AlHV-1 induces an acute and fatal lymphoproliferative disease named malignant catarrhal fever (MCF) in many ruminants, including cattle and the rabbit model. Latency has been shown to be essential for MCF induction. However, the mechanisms causing the activation and proliferation of infected CD8+ T cells are unknown. Many ?-HVs express microRNAs (miRNAs). These small noncoding RNAs can suppress host or viral target genes involved in various pathways and are thought to facilitate viral infection and/or mediate activation and proliferation of infected lymphocytes. AlHV-1 genome has been predicted to encode a large number of miRNAs. However, their precise contribution in viral infection and pathogenesis in vivo remains unknown. Here, we have cloned small RNAs and sequenced 36 potential miRNAs expressed in a lymphoblastoid cell line propagated from a calf infected with AlHV-1 and developing MCF. Among the sequenced candidate miRNAs, 32 were expressed on the reverse strand of the genome in two main clusters. The expression of these 32 viral miRNAs was further validated using Northern blot and qRT-PCR in lymphoid organs of MCF-developing calves or rabbits. To determine the concerted contribution in MCF of 28 viral miRNAs clustered in the non-protein-coding region of the AlHV-1 genome, a recombinant virus was produced. The absence of these 28 miRNAs did not affect viral growth in vitro nor MCF induction in rabbits, demonstrating that AlHV-1 miRNAs clustered in the non-protein-coding genomic region are not essential for MCF induction. Small RNA sequencing from total RNA from AlHV-1-infected bovine lymphoblastoid cell line propagated with interleukin 2
Project description:Alcelaphine herpesvirus 1 (AlHV-1) is a γ-herpesvirus (γ-HV) carried asymptomatically by wildebeest. Upon cross-species transmission, AlHV-1 induces an acute and fatal lymphoproliferative disease named malignant catarrhal fever (MCF) in many ruminants, including cattle and the rabbit model. Latency has been shown to be essential for MCF induction. However, the mechanisms causing the activation and proliferation of infected CD8+ T cells are unknown. Many γ-HVs express microRNAs (miRNAs). These small noncoding RNAs can suppress host or viral target genes involved in various pathways and are thought to facilitate viral infection and/or mediate activation and proliferation of infected lymphocytes. AlHV-1 genome has been predicted to encode a large number of miRNAs. However, their precise contribution in viral infection and pathogenesis in vivo remains unknown. Here, we have cloned small RNAs and sequenced 36 potential miRNAs expressed in a lymphoblastoid cell line propagated from a calf infected with AlHV-1 and developing MCF. Among the sequenced candidate miRNAs, 32 were expressed on the reverse strand of the genome in two main clusters. The expression of these 32 viral miRNAs was further validated using Northern blot and qRT-PCR in lymphoid organs of MCF-developing calves or rabbits. To determine the concerted contribution in MCF of 28 viral miRNAs clustered in the non-protein-coding region of the AlHV-1 genome, a recombinant virus was produced. The absence of these 28 miRNAs did not affect viral growth in vitro nor MCF induction in rabbits, demonstrating that AlHV-1 miRNAs clustered in the non-protein-coding genomic region are not essential for MCF induction.
Project description:IntroductionMalignant catarrhal fever (MCF) is a rare, under-explored lethal viral infection of cattle with gammaherpesvirus aetiological agents. Most often, the disease occurs on farms where cattle and sheep are kept together. However, other trigger mechanisms and environmental factors contribute. This study investigates the causation of MCF.Material and methodsAn outbreak of MCF occurred in June - August 2017 in Kharchev village in Irkutsk Oblast, Russia. In this paper, we provide epidemiological (sanitary status of pastures, watering places, and premises) and weather data during the outbreak, and descriptions of the clinical signs and post-mortem changes in cattle. The virus was detected and isolated from pathological material samples and identified by molecular methods.ResultsExtreme weather conditions, mixed-herd cattle and sheep farming, and unsatisfactory feed quality contributed to the outbreak. A virus related to herpesvirus OvHV2 was isolated and typed (MCF/Irkutsk/2017). Phylogenetic analysis showed its close genetic relationship to isolates from cattle and sheep in Germany, USA, and the Netherlands.ConclusionSporadic outbreaks of MCF caused by biotic and abiotic factors together are typical for the Russian Federation, and the Irkutsk outbreak epitomised this. Temperature anomalies caused pasture depletion, resulting in feed and water deficiency for grazing animals and dehydration and acidosis. Heat stress in animals ultimately led to the occurrence of MCF in the herd.
Project description:This study is the first to partially quantify the potential economic benefits that a vaccine, effective at protecting cattle against malignant catarrhal fever (MCF), could accrue to pastoralists living in East Africa. The benefits would result from the removal of household resource and management costs that are traditionally incurred avoiding the disease. MCF, a fatal disease of cattle caused by a virus transmitted from wildebeest calves, has plagued Maasai communities in East Africa for generations. The threat of the disease forces the Maasai to move cattle to less productive grazing areas to avoid wildebeest during calving season when forage quality is critical. To assess the management and resource costs associated with moving, we used household survey data. To estimate the costs associated with changes in livestock body condition that result from being herded away from wildebeest calving grounds, we exploited an ongoing MCF vaccine field trial and we used a hedonic price regression, a statistical model that allows estimation of the marginal contribution of a good's attributes to its market price. We found that 90 percent of households move, on average, 82 percent of all cattle away from home to avoid MCF. In doing so, a herd's productive contributions to the household was reduced, with 64 percent of milk being unavailable for sale or consumption by the family members remaining at the boma (the children, women, and the elderly). In contrast cattle that remained on the wildebeest calving grounds during the calving season (and survived MCF) remained fully productive to the family and gained body condition compared to cattle that moved away. This gain was, however, short-lived. We estimated the market value of these condition gains and losses using hedonic regression. The value of a vaccine for MCF is the removal of the costs incurred in avoiding the disease.
Project description:A multiplex real-time PCR was developed using a single pair of primers and fluorescent probes specific for five malignant catarrhal fever viruses and an internal positive control. The assay was able to simultaneously detect and differentiate the viruses in clinical samples with high sensitivity (97.2%) and specificity (100%).
Project description:Alcelaphine gammaherpesvirus 1 (AlHV-1) is a member of the Gammaherpesvirinae subfamily and establishes asymptomatic latent infection in its natural host species, the wildebeest. Cross-species transmission to various ruminant species including cattle can occur, resulting in the induction of malignant catarrhal fever (MCF), a deadly peripheral T cell lymphoproliferative disease. Here, we experimentally infected calves to confirm that AlHV-1 latency-associated gene expression is essential for persistent infection of CD8+ T cells and MCF development. Then, deep sequencing of the T cell receptor repertoire revealed an oligoclonal expansion of peripheral CD8+ T cells during bovine MCF, associated with transcriptomic and epigenetic changes identified by (sc)RNA-seq and ATAC-seq analyses which indicated a mixed effector/memory and exhaustion phenotype of infected cells in vivo. Analysis of the viral genome transcription identified viral genomic regions being expressed in infected CD8+ T cells, such as the region predicted to encode the gene A10. A10 encodes a transmembrane signaling protein displaying multiple tyrosine residues, with predicted ITAM and SH3 motifs. We could demonstrate that impaired expression of A10 did not affect AlHV-1 replication in vitro but rendered AlHV-1 unable to induce MCF in the rabbit experimental model, and we showed that A10 is phosphorylated in T lymphocytes in vitro and affects T cell signaling. Finally, while AlHV-1 viruses expressing mutated forms of A10 devoid of ITAM and/or SH3 motifs could induce MCF, an A10 knock-in viral mutant unable to phosphorylate tyrosine residues resulted in the absence of MCF development. Overall, we identified AlHV-1-induced phenotypic changes in CD8+ T cells during MCF and demonstrated that A10 expression in infected CD8+ T lymphocytes results in the dysregulation of T cell signaling and MCF.
Project description:Alcelaphine gammaherpesvirus 1 (AlHV-1) is a member of the Gammaherpesvirinae subfamily and establishes asymptomatic latent infection in its natural host species, the wildebeest. Cross-species transmission to various ruminant species including cattle can occur, resulting in the induction of malignant catarrhal fever (MCF), a deadly peripheral T cell lymphoproliferative disease. Here, we experimentally infected calves to confirm that AlHV-1 latency-associated gene expression is essential for persistent infection of CD8+ T cells and MCF development. Then, deep sequencing of the T cell receptor repertoire revealed an oligoclonal expansion of peripheral CD8+ T cells during bovine MCF, associated with transcriptomic and epigenetic changes identified by (sc)RNA-seq and ATAC-seq analyses which indicated a mixed effector/memory and exhaustion phenotype of infected cells in vivo. Analysis of the viral genome transcription identified viral genomic regions being expressed in infected CD8+ T cells, such as the region predicted to encode the gene A10. A10 encodes a transmembrane signaling protein displaying multiple tyrosine residues, with predicted ITAM and SH3 motifs. We could demonstrate that impaired expression of A10 did not affect AlHV-1 replication in vitro but rendered AlHV-1 unable to induce MCF in the rabbit experimental model, and we showed that A10 is phosphorylated in T lymphocytes in vitro and affects T cell signaling. Finally, while AlHV-1 viruses expressing mutated forms of A10 devoid of ITAM and/or SH3 motifs could induce MCF, an A10 knock-in viral mutant unable to phosphorylate tyrosine residues resulted in the absence of MCF development. Overall, we identified AlHV-1-induced phenotypic changes in CD8+ T cells during MCF and demonstrated that A10 expression in infected CD8+ T lymphocytes results in the dysregulation of T cell signaling and MCF.
Project description:Alcelaphine gammaherpesvirus 1 (AlHV-1) is a member of the Gammaherpesvirinae subfamily and establishes asymptomatic latent infection in its natural host species, the wildebeest. Cross-species transmission to various ruminant species including cattle can occur, resulting in the induction of malignant catarrhal fever (MCF), a deadly peripheral T cell lymphoproliferative disease. Here, we experimentally infected calves to confirm that AlHV-1 latency-associated gene expression is essential for persistent infection of CD8+ T cells and MCF development. Then, deep sequencing of the T cell receptor repertoire revealed an oligoclonal expansion of peripheral CD8+ T cells during bovine MCF, associated with transcriptomic and epigenetic changes identified by (sc)RNA-seq and ATAC-seq analyses which indicated a mixed effector/memory and exhaustion phenotype of infected cells in vivo. Analysis of the viral genome transcription identified viral genomic regions being expressed in infected CD8+ T cells, such as the region predicted to encode the gene A10. A10 encodes a transmembrane signaling protein displaying multiple tyrosine residues, with predicted ITAM and SH3 motifs. We could demonstrate that impaired expression of A10 did not affect AlHV-1 replication in vitro but rendered AlHV-1 unable to induce MCF in the rabbit experimental model, and we showed that A10 is phosphorylated in T lymphocytes in vitro and affects T cell signaling. Finally, while AlHV-1 viruses expressing mutated forms of A10 devoid of ITAM and/or SH3 motifs could induce MCF, an A10 knock-in viral mutant unable to phosphorylate tyrosine residues resulted in the absence of MCF development. Overall, we identified AlHV-1-induced phenotypic changes in CD8+ T cells during MCF and demonstrated that A10 expression in infected CD8+ T lymphocytes results in the dysregulation of T cell signaling and MCF.
Project description:Malignant catarrhal fever (MCF) is a fatal lymphoproliferative disease affecting bovids, cervids and other ruminant species caused by viruses belonging to subfamily Gammaherpesvirinae, genus Macavirus. Among the 10 MCF viruses known to cause the disease, alcelaphine herpesvirus 1 (AlHV-1) and ovine herpesvirus 2 (OvHV-2) are the two most widely prevalent causative organisms. The AlHV-1 naturally infects wildebeest and causes wildebeest associated MCF (WA-MCF) in cattle in regions of African sub-continent. The OvHV-2 is prevalent in all varieties of domestic sheep as a sub-clinical infection and causes sheep associated MCF (SA-MCF) in susceptible ruminants in most regions of the world. In India, the detection of cases of SA-MCF in cattle and OvHV-2 infection in sheep during the last decade has established the presence of the virus in native sheep of the country. The present review presents up to date information on various aspects of SA-MCF and its causative agent OvHV-2 with special reference to Indian scenario.