Two Different Macaviruses, ovine herpesvirus-2 and caprine herpesvirus-2, behave differently in water buffaloes than in cattle or in their respective reservoir species

Serological Detection of Ovine Gammaherpesvirus 2 Antibodies in Dairy Farms from Southern Brazil

Sheep-associated malignant catarrhal fever (SA-MCF) is a severe lymphoproliferative vascular disease of cattle that is caused by ovine gammaherpesvirus 2 (OvGHV2), which is a Macavirus within the Gammaherpesvirinae subfamily. SA-MCF occurs worldwide in several mammalian hosts. Alternatively, alcelaphine gammaherpesvirus 1 (AlGHV1) is a Macavirus that causes wildebeest-associated malignant catarrhal fever (MCF), which principally occurs in cattle from Africa. Previous serological assays to evaluate the presence of MCF in mammals used a competitive inhibition enzyme-linked immunosorbent assay (CI-ELISA). This CI-ELISA is based on the 15A antigenic epitope that is common to all Macavirus associated with the development of MCF in their respective hosts. This study evaluated an indirect MCF-specific ELISA assay based on the AlGHV1 C500 strain to detect antibodies against OvGHV2 in 43 closed dairy cattle farms from Southern Brazil. These farms are located in a region where subclinical infections by OvGHV2 have been detected in free-ranging wild boars (Sus scrofa). Sheep or goats were not reared at these farms or within the proximity of these farms. Risk factors associated with seropositivity to OvGHV2 were evaluated, while the possible participation of subclinically infected wild boars in the dissemination of OvGHV2 was estimated using spatial analysis. Sera from 29 dairy cows from 16 farms demonstrated sample/positive (S/P) values considered positive with this MCF-specific ELISA (cutoff S/P, 0.063). The S/P values for the positive dairy cows varied between 0.0633 and 0.2510 (mean, 0.0998; standard deviation, 0.0476). At least one cow was seropositive in 16/43 (37.2%) of these farms, with seropositivity identified in 29/367 (7.9%) of dairy cows maintained at these farms. Additionally, dairy cows raised within the intensive system had a more than threefold higher chance of being seropositive to OvGHV2 relative to those reared within the semi-intensive system. Furthermore, the spatial evaluation revealed that cows on dairy farms within a 50 km radius of the home range of subclinically infected wild boars had an increased risk of being seropositive to this assay. These findings demonstrated that the AlGHV1 C500-specific MCF ELISA can be efficiently used to monitor the occurrence of OvGHV2 in cattle. In addition, the occurrence of subclinically infected free-ranging wild boars within a radius of 50 km from susceptible cattle may be a possible risk factor for the occurrence of OvGHV2-related infections in these animals from Southern Brazil. These initial results are fundamental to understanding the epidemiology of OvGHV2-associated infections and clinical SA-MCF in mammals in Brazil.

Transplacental Infections Associated with Macavirus in Aborted Bovine Fetuses

The Macavirus genus, Gammaherpesvirinae subfamily, Herpesviridae family, contains ovine gammaherpesvirus 2 (OvGHV2), the cause of sheep-associated malignant catarrhal fever (SA-MCF). Members of the Macavirus genus associated with the development of malignant catarrhal fever (MCF) in their respective hosts share the 15A antigenic epitope, are conserved within the DNA polymerase gene and are collectively referred to as the malignant catarrhal fever virus (MCFV) complex. The ability of MCFV and/or OvGHV2 to produce abortions in ruminants is currently unknown, with little documentation of infections by these agents in bovine fetuses. This report presents the findings observed due to the detection of OvGHV2 DNA and MCFV tissue antigens in aborted bovine fetuses from southern Brazil. Four aborted bovine fetuses from three farms, located in a geographical region of Paraná State with elevated immunohistochemical (IHC) prevalence of MCFV tissue antigens, with gestational ages varying between 78 to 208 days were investigated. Significant gross and histopathological alterations were not observed in any of these fetuses. An IHC assay using the 15A-monoclonal antibody (15A-MAb), which is based on the 15A antigenic epitope of Macavirus, identified MCFV tissue antigens in multiple organs from two fetuses (#1 and #4); however, positive immunoreactivity to the 15A-MAb IHC assay was not detected in Fetus #2 and #3. Molecular testing amplified OvGHV2 DNA only from the myocardium and lungs of Fetus #1 that had positive intracytoplasmic immunoreactivity to the 15A-MAb IHC assay in these tissues. Furthermore, infections by Leptospira spp. were confirmed by molecular assays in fetuses #1, #3, and #4, while PCR detected Neospora caninum in the myocardium of Fetus #2. Additionally, molecular assays to identify well-known fetopathy agents of cattle, including bovine viral diarrhea virus, bovine alphaherpesvirus 1, Histophilus somni, and Listeria monocytogenes, did not amplify the nucleic acids of these pathogens. PCR assays to identify bovine gammaherpesvirus 6 (BoGHV6), another Macavirus known to infect cattle in Brazil, were unsuccessful. These findings confirmed that the 15A-MAb IHC assay can be efficiently used to detect MCFV antigens in organs of aborted bovine fetuses. The identification of MCFV antigens with the simultaneous detection of OvGHV2 DNA confirmed that Fetus #1 was infected by OvGHV2 and added to the few descriptions of this infection in aborted fetuses of ruminants worldwide. Moreover, the IHC detection of MCFV in multiple organs of Fetus #4, without the molecular detection of OvGHV2 or BoGHV6, may suggest that this fetus was infected by a Macavirus that was not previously diagnosed in cattle herds from Brazil. These findings strongly suggest that OvGHV2 and MCFV can produce transplacental infections in cattle.

Subclinical Ovine Gammaherpesvirus 2-Related Infections in Free-Ranging Wild Boars (Sus scrofa) from Southern Brazil

Ovine gammaherpesvirus 2 (OvGHV2), is a Macavirus and the cause of sheep-associated malignant catarrhal fever (SA-MCF), in which sheep are the asymptomatic reservoir hosts. Susceptible mammalian populations infected by OvGHV2 may develop clinical SA-MCF or subclinical infections. All members of the Macavirus genus known to be associated with MCF are collectively referred to as the MCF virus (MCFV) complex. This report describes the occurrence of subclinical OvGHV2-related infections in free-ranging wild boars (Sus scrofa) from southern Brazil. Specific body organs (n = 14) and biological samples (nasal and oral swabs; n = 17) were collected from 24 asymptomatic wild boars from a conservation unit located within the Central-eastern mesoregion of Paraná State. Organs were processed to observe histopathological patterns suggestive of diseases of domestic animals; only pulmonary samples were used in an immunohistochemical assay designed to detect MCFV tissue antigens. Furthermore, all samples were submitted to molecular assays designed to detect the OvGHV2 tegument protein gene. Viral-induced pneumonia was diagnosed in two wild boars; one of these contained OvGHV2 DNA, with MCFV antigens identified in the other. Additionally, MCFV tissue antigens were detected within pulmonary epithelial cells of the lungs with and without pulmonary disease. Collectively, OvGHV2 was detected in 37.5% (9/24) of all wild boars, with detection occurring in the organs of 57.1% (8/14) wild boars and the oral cavity of one animal. These results demonstrated that these wild boars were subclinically infected by OvGHV2, and that infection produced typical pulmonary alterations. In addition, the detection of OvGHV2 within the oral cavity of one wild boar may suggest that this animal may be a potential disseminator of this pathogen to susceptible animal populations, including livestock and wildlife, acting as a possible bridge host for OvGHV2. Furthermore, infection by OvGHV2 probably occurred due to incidental contact with asymptomatic sheep maintained within the surrounding rural areas and not within the conservation units.

Quantification of ovine gammaherpesvirus 2 in clinical cases of cattle with sheep-associated malignant catarrhal fever

Ovine gammaherpesvirus 2 (OvGHV2) produces sheep-associated malignant catarrhal fever (SA-MCF), a frequently lethal, lymphoproliferative disease that is characterized by widespread vascular lesions. Most studies that evaluated the viral load in tissues of animals with SA-MCF were done in the Northern Hemisphere, with scant information from the Southern part of the globe. This study investigated the viral load of OvGHV2 in the tissues of cattle and an underdeveloped fetus with SA-MCF from three distinct biomes of Brazil. All animals had clinical and histopathological manifestations consistent with SA-MCF. Molecular testing identified the OvGHV2 tegument protein and glycoprotein B genes in the tissues of all animals and the fetus. Viral quantification based on the DNA polymerase gene detected elevated loads of OvGHV2 in tissues with histopathological evidence of SA-MCF and organs with unknown histological data, except for the tissues of the fetus, where the viral load was comparatively reduced. The viral loads detected in multiple organs of cattle from this study with SA-MCF are consistent with those identified in different animal species from the USA and Europe. The detection of a low viral load of OvGHV2 in fetal tissue confirmed transplacental dissemination since elevated viral loads were detected in multiple tissues of the cow with SA-MCF. Furthermore, the elevated viral loads detected in the pulmonary tissues of cattle with interstitial pneumonia indicate that OvGHV2 is an inductor of pulmonary disease in cattle.

Characterization of ovine gammaherpesvirus 2 in a goat by nanoplate digital PCR and other diagnostic methods

The Macavirus, ovine gammaherpesvirus 2 (OvGHV2), is the cause of sheep-associated malignant catarrhal fever (SA-MCF). Although SA-MCF occurs in a wide range of mammalian hosts, there are few descriptions of this disease and/or infection in goats. This report describes the findings observed in a goat that was infected by OvGHV2 and adds to the rare description of this infection in this animal species. A 6.5-year-old, female, Anglo Nubian goat, with a neurological syndrome, that was euthanized after severe esophageal obstruction was investigated to determine the cause of the brain disease. Histopathology revealed cerebral cortical edema, hemorrhagic rhombencephalitis, severe hepatic necrosis, and atrophic enteritis. An immunohistochemical (IHC) assay identified intracytoplasmic antigens of a malignant catarrhal fever virus (MCFV) within epithelial cells of the intestine, liver, lungs, and kidneys. A semi-nested PCR assay amplified the partial fragment of the OvGHV2 tegument protein gene from the intestine, confirming that the MCFV identified by IHC was OvGHV2. A qPCR assay that targeted the OvGHV2 polymerase gene revealed an elevated quantification cycle (Cq), while nanoplate-based digital PCR (dPCR) detected low viral copy load within the OvGHV2 DNA. Furthermore, the nucleic acids of several disease pathogens associated with diseases in ruminants were not amplified. However, the exact cause of the neurological syndrome remained obscure since nucleic acids of neurological disease pathogens such as bovine viral diarrhea virus, bovine alphaherpesvirus 1 and 5, Histophilus somni, and OvGHV2 were not detected from the brain. Collectively, the results of the Cq and dPCR confirmed that this goat was infected with a low viral load of OvGHV2, which probably was insufficient to induce the typical histopathological alterations and subsequent clinical manifestations associated with SA-MCF and/or infections by OvGHV2. Therefore, elevated viral loads of OvGHV2 would have been required for the development of histological lesions and/or clinical manifestations of SA-MCF in this goat. Furthermore, the dPCR methodology can be used for the efficient detection and quantification of OvGHV2 DNA in animals with or without clinical and/or histopathological evidence of SA-MCF. Additionally, since previous cases of OvGHV2 infections in goats did not have the typical clinical manifestations of SA-MCF, one wonders if this Macavirus can induce SA-MCF in goats.

Evidence for a Novel Gammaherpesvirus as the Putative Agent of Malignant Catarrhal Fever Disease in Roan Antelopes (Hippotragus equinus)

Upon the sudden death of two captive roan antelopes (Hippotragus equinus) that had suffered from clinical signs reminiscent of malignant catarrhal fever (MCF) in a German zoo, next generation sequencing of organ samples provided evidence of the presence of a novel gammaherpesvirus species. It shares 82.40% nucleotide identity with its so far closest relative Alcelaphine herpesvirus 1 (AlHV-1) at the polymerase gene level. The main histopathological finding consisted of lympho-histiocytic vasculitis of the pituitary rete mirabile. The MCF-like clinical presentation and pathology, combined with the detection of a nucleotide sequence related to that of AlHV-1, indicates a spillover event of a novel member of the genus Macavirus of the Gammaherpesvirinae, probably from a contact species within the zoo. We propose the name Alcelaphine herpesvirus 3 (AlHV-3) for this newly identified virus.

Gammaherpesvirus Infections in Cattle in Europe

The genus Macavirus, subfamily Gammaherpesvirinae, comprises ungulate viruses that infect domestic and wild ruminants and swine. They cause asymptomatic latent infections in reservoir hosts and malignant catarrhal fever in susceptible species. Lung, spleen, bronchial lymph node, and tongue were collected from 448 cattle (348 necropsied, 100 slaughtered) in Switzerland, United Kingdom, Finland, Belgium, and Germany to determine their infection with bovine herpesvirus-6 (BoHV-6) and gammaherpesviruses of other ruminants, i.e., ovine herpesvirus-1 and -2, caprine herpesvirus-2, and bison lymphotropic herpesvirus, using quantitative PCR. Only BoHV-6 was detected, with an overall frequency of 32%, ranging between 22% and 42% in the different countries. Infection was detected across all ages, from one day after birth, and was positively correlated with age. There was no evidence of an association with specific disease processes. In positive animals, BoHV-6 was detected in all organs with high frequency, consistently in the lungs or spleen. Viral loads varied substantially. In BoHV-6-positive gravid cows, organs of fetuses tested negative for infection, indicating that the virus is not vertically transmitted. Our results confirm previous data indicating that BoHV-6 is a commensal of domestic cattle not associated with disease processes and confirm that infections with other macaviruses are rare and sporadic.

Viral infections shared between water buffaloes and small ruminants in Switzerland

Importation of exotic animals that may harbor infectious agents poses risks for native species with potentially severe impacts on animal health and animal production. Although the Asian water buffalo (Bubalus bubalis) population in Europe is steadily increasing, its susceptibility to viral infections and its role for interspecies transmission is largely unknown. To identify viral infections that are shared between exotic water buffaloes and native small ruminants, we collected blood samples from 3 Swiss farms on which water buffaloes were kept either without, or together with, sheep or goats. These samples were analyzed by next-generation sequencing (NGS) as well as by selected conventional tests, including PCR, ELISA, and in some cases a virus neutralization test. By NGS, a novel virus of the genus Gemykrogvirus (GyKV; Genomoviridae) was first detected in the buffaloes on one farm, and subsequently confirmed by PCR, and was also detected in the co-housed sheep. In contrast, this virus was not detected in buffaloes on the farms without sheep. Moreover, conventional methods identified a number of viral infections that were not shared between the exotic and the native animals, and provided evidence for potential roles of water buffaloes in the epidemiology of ruminant pestiviruses, especially bovine viral diarrhea virus, bluetongue virus, and possibly bovine alphaherpesvirus 2. Our results clearly indicate that water buffaloes are susceptible to interspecies viral transmission and may act as intermediate hosts, or even as reservoirs, for these viruses.

Molecular detection and characterization of ovine herpesvirus-2 using heminested PCR in Pakistan

Background

Malignant catarrhal fever (MCF) is a highly fatal lymphoproliferative disease of cattle, deer, bison, water buffalo, and pigs caused by the gamma-herpesviruses alcelaphine herpesvirus-1 (AlHV-1) and ovine herpesvirus-2 (OvHV-2).

Objectives

This study aimed to determine the prevalence of OvHV-2 in sheep, goats, cattle, and buffalo in Rawalpindi and Islamabad, Pakistan, by applying molecular and phylogenetic methods.

Methods

Blood samples were aspirated from sheep (n = 54), goat (n = 50), cattle (n = 46) and buffalo (n= 50) at a slaughterhouse and several farms. The samples were subjected to heminested polymerase chain reaction (PCR), followed by sequencing and phylogenetic analysis of the OvHV-2 POL gene and the OvHV-2 ORF75 tegument protein gene.

Results

The highest percentage of MCF positive samples was in sheep (13%), whereas goat, cattle, and buffalo had lower positive percentages, 11%, 9%, and 6.5%, respectively. Four OvHV-2-positive PCR products obtained from sheep samples were sequenced. The sequences obtained were submitted to the NCBI GenBank database (MK852173 for the POL gene; MK840962, MK852171, and MK852172 for the ORF75 tegument protein gene). Phylogenetic analysis revealed a close similarity of study sequences with those of worldwide samples.

Conclusions

This study is the first cross-sectional study on the prevalence and molecular detection of OvHV-2 in apparently healthy cattle and buffalo that could be carrying OvHV-2 acquired from OvHV-2-positive sheep and goats. The results indicate that OvHV-2 is circulating in Pakistan. Further studies are needed to characterize OvHV-2 and elucidate further its prevalence.

Rapid and simple colorimetric loop-mediated isothermal amplification (LAMP) assay for the detection of Bovine alphaherpesvirus 1

As the causative agent of Infectious Bovine Rhinotracheitis (IBR) and Infectious Pustular Vulvovaginitis/Balanoposthitis (IPV/IPB), Bovine alphaherpesvirus 1 (BoHV-1) is responsible for high economic losses in the cattle industry worldwide. This study aimed to establish a fast, colorimetric loop-mediated isothermal amplification (LAMP) assay for the detection of viral DNA. Phenol red is used as pH-sensitive readout, relying on a distinct color change from pink to yellow in case of a positive reaction. LAMP reactions with different primers were compared and a newly designed set targeting the gene encoding the tegument protein V67 provided best results, enabling readout within 8-30 min. LAMP showed less cross-reactions with other ruminant alphaherpesviruses than qPCR but was 10-fold less sensitive. However, LAMP still detected down to 14 copies. The test performance was evaluated using 26 well-characterized nasal swabs from cattle with respiratory disease. All samples were correctly identified when using column-extracted DNA. Using a simple DNA precipitation method, only two weak-positive samples turned indeterminate. Combining this DNA precipitation with a makeshift water bath heated by a gastronomic immersion heater allowed successful application of the colorimetric LAMP assay under resource-limited conditions. This technique can therefore help in managing IBR/IPV outbreaks where sophisticated laboratory equipment is unavailable.

Sheep-Associated Malignant Catarrhal Fever: Role of Latent Virus and Macrophages in Vasculitis

Malignant catarrhal fever (MCF) is a sporadic, generally fatal disease caused by gammaherpesviruses in susceptible dead-end hosts. A key pathological process is systemic vasculitis in which productively infected cytotoxic T cells play a major role. Nonetheless, the pathogenesis of MCF vasculitis is not yet clear. We hypothesized that it develops due to an interaction between virus-infected cells and immune cells, and we undertook a retrospective in situ study on the rete mirabile arteries of confirmed ovine gammaherpesvirus-2 (OvHV-2)-associated MCF cases in cattle, buffalo, and bison. Our results suggest that the arteritis develops from an adventitial infiltration of inflammatory cells from the vasa vasorum, and recruitment of leukocytes from the arterial lumen that leads to a superimposed infiltration of the intima and media that can result in chronic changes including neointimal proliferation. We found macrophages and T cells to be the dominant infiltrating cells, and both could proliferate locally. Using RNA in situ hybridization and immunohistology, we showed that the process is accompanied by widespread viral infection, not only in infiltrating leukocytes but also in vascular endothelial cells, medial smooth muscle cells, and adventitial fibroblasts. Our results suggest that OvHV-2-infected T cells, monocytes, and locally proliferating macrophages contribute to the vasculitis in MCF. The initial trigger or insult that leads to leukocyte recruitment and activation is not yet known, but there is evidence that latently infected, activated endothelial cells play a role in this. Activated macrophages might then release the necessary pro-inflammatory mediators and, eventually, induce the characteristic vascular changes.

Cerebral Ovine Herpesvirus 2 Infection of Cattle Is Associated With a Variable Neuropathological Phenotype

Cross-species infection with ovine herpesvirus 2 (OvHV-2) in cattle causes malignant catarrhal fever (MCF). MCF may involve the central nervous system (CNS) with necrotizing arteritis and/or vasculitis described to be unique to MCF and discriminatory compared to other viral CNS infections. However, a systematic histopathological characterization of the neural form of MCF in cattle is lacking. We examined medulla oblongata (n = 9) or the entire brain (n = 9) of 18 cattle in which OvHV-2 was identified by quantitative polymerase chain reaction (qPCR), in order to pinpoint potential variations in neuropathology. In 2/18 animals (11%) no lesions were identified, while 16/18 cattle (89%) had brain lesions of varying severity. Presence and quantities of OvHV-2 nucleic acid were determined by in situ hybridization and qPCR, respectively, and were related to the severity of lesions. Fifteen of 18 animals (83%) showed vasculitis, which was mainly of the lymphohistiocytic type, while pathognomonic necrotizing arteritis was only rarely present. Neuroparenchymal lesions included gliosis and/or neuronal changes in 7/16 brains with lesions (44%). The number of CD3+ lymphocytes was highest in animals with simultaneous vascular and neuroparenchymal lesions and high viral genome load. In one animal, OvHV-2 was exclusively observed in CD3+ lymphocytes but not in neurons or microglia. In conclusion, the neuropathological phenotype of bovine MCF in the brain was variable. In some cases, lesions mimicked neurotropic viral encephalitis, while pathognomonic necrotizing arteritis was not a consistent feature of neural MCF. Therefore, molecular detection of OvHV-2 is warranted in the presence of nonsuppurative encephalitis and in the absence of necrotizing arteritis.

Ovine Herpesvirus 2 Encodes a Previously Unrecognized Protein, pOv8.25, That Targets Mitochondria and Triggers Apoptotic Cell Death

Ovine herpesvirus 2 (OvHV-2) circulates among sheep without causing disease. However, upon transmission to cattle, the same virus instigates a frequently lethal disease, malignant catarrhal fever (MCF). While the cause of death and pathogenesis of tissue lesions are still poorly understood, MCF is characterized by the accumulation of lymphocytes in various tissues, associated with vasculitis and cell death. As infectious virus is hardly present in these lesions, the cause of cell death cannot be explained simply by viral replication. The significance of our research is in identifying and characterizing a previously overlooked gene of OvHV-2 (Ov8.25), which is highly expressed in animals with MCF. Its encoded protein targets mitochondria, causing apoptosis and necrosis, thus contributing to an understanding of the source and nature of cell death. As the corresponding genetic locus is also active in the context of MCF due to a different macavirus, we may have detected a common denominator of the disease phenotype.

Malignant catarrhal fever (MCF) is a rare but frequently lethal disease of certain cloven-hoofed animals. At least 10 different viruses, all members of the Macavirus genus in the subfamily Gammaherpesvirinae, are known as causative agents of MCF. Among these, ovine herpesvirus 2 (OvHV-2) is the most frequent and economically most important MCF agent. Phenotypically, MCF is characterized by severe lymphocytic arteritis-periarteritis, which leads to the accumulation of activated lymphocytes accompanied by apoptosis and necrosis in a broad range of tissues. However, a viral factor that might be responsible for tissue damage has not yet been identified. We have studied a seemingly intergenic locus on the OvHV-2 genome, which was previously shown to be transcriptionally highly active in MCF-affected tissue. We identified by 5′ and 3′ rapid amplification of cDNA ends (RACE) a conserved, double-spliced transcript that encoded a 9.9-kDa hydrophobic protein. The newly detected gene, Ov8.25, and its splicing pattern were conserved among OvHV-2 strains of different origins. Upon transient expression of synthetic variants of this gene in various cell types, including bovine lymphocytes, the protein (pOv8.25) was shown to target mitochondria, followed by caspase-dependent apoptosis and necrosis. Notably, a deletion mutant of the same protein lost these abilities. Finally, we detected pOv8.25 in brain-infiltrating lymphocytes of cattle with MCF. Thus, the cell death-causing properties of pOv8.25 in affected cells may be involved in the emergence of typical MCF-associated apoptosis and necrosis. Thus, we have identified a novel OvHV-2 protein, which might contribute to the phenotype of MCF-related lesions.

IMPORTANCE Ovine herpesvirus 2 (OvHV-2) circulates among sheep without causing disease. However, upon transmission to cattle, the same virus instigates a frequently lethal disease, malignant catarrhal fever (MCF). While the cause of death and pathogenesis of tissue lesions are still poorly understood, MCF is characterized by the accumulation of lymphocytes in various tissues, associated with vasculitis and cell death. As infectious virus is hardly present in these lesions, the cause of cell death cannot be explained simply by viral replication. The significance of our research is in identifying and characterizing a previously overlooked gene of OvHV-2 (Ov8.25), which is highly expressed in animals with MCF. Its encoded protein targets mitochondria, causing apoptosis and necrosis, thus contributing to an understanding of the source and nature of cell death. As the corresponding genetic locus is also active in the context of MCF due to a different macavirus, we may have detected a common denominator of the disease phenotype.

An Update on the Known Host Range of the Brazilian Vaccinia Virus: An Outbreak in Buffalo Calves

Even nearly forty years after the eradication of smallpox, members of the Poxviridae family continue to be the focus of an increasing number of studies. Among these studies, prominently stands vaccinia virus, an orthopoxvirus that is associated with bovine vaccinia outbreaks. Although more frequently associated with infections in cattle and humans, the host range of vaccinia virus is not restricted only to these hosts. There are several instances of molecular and serological evidence of circulation of vaccinia virus among wildlife species. In addition, viral isolation has confirmed a broad spectrum of vaccinia virus hosts. In this report, we provide a brief update on the host range of Brazilian vaccinia virus, and present a case description of an outbreak in domestic buffalo calves from Northeastern Brazil that corroborates previous serological and molecular studies. Furthermore, in the present study, vaccinia virus has been isolated for the first time in buffaloes, and referred to as vaccinia virus Pernambuco (VACV-PE). Phylogenetic reconstruction was based on A56R clustered VACV-PE with vaccinia virus isolates belonging to group 1 Brazilian vaccinia virus. Furthermore, the vaccinia virus genome was detected in the milk of a lactating cow, which thereby revealed a pathway for future studies on the possible impact of vaccinia virus on buffalo milk and milk products. Taken together, these results provide the first description of clinical disease caused by vaccinia virus in buffaloes in South America. They also raise new questions about the chain of transmission of this virus.

How Host Specific Are Herpesviruses? Lessons from Herpesviruses Infecting Wild and Endangered Mammals

Herpesviruses are ubiquitous and can cause disease in all classes of vertebrates but also in animals of lower taxa, including molluscs. It is generally accepted that herpesviruses are primarily species specific, although a species can be infected by different herpesviruses. Species specificity is thought to result from host-virus coevolutionary processes over the long term. Even with this general concept in mind, investigators have recognized interspecies transmission of several members of the Herpesviridae family, often with fatal outcomes in non-definitive hosts-that is, animals that have no or only a limited role in virus transmission. We here summarize herpesvirus infections in wild mammals that in many cases are endangered, in both natural and captive settings. Some infections result from herpesviruses that are endemic in the species that is primarily affected, and some result from herpesviruses that cause fatal disease after infection of non-definitive hosts. We discuss the challenges of such infections in several endangered species in the absence of efficient immunization or therapeutic options.

Neuropathological survey reveals underestimation of the prevalence of neuroinfectious diseases in cattle in Switzerland

Neuroinfectious diseases in livestock represent a severe threat to animal health, but their prevalence is not well documented and the etiology of disease often remains unidentified. The aims of this study were to generate baseline data on the prevalence of neuroinfectious diseases in cattle in Switzerland by neuropathological survey, and to identify disease-associated pathogens. The survey was performed over a 1-year period using a representative number of brainstem samples (n=1816) from fallen cattle. In total, 4% (n=73) of the animals had significant lesions, the most frequent types of which were indicative of viral (n=27) and bacterial (n=31) etiologies. Follow-up diagnostics by immunohistochemistry, PCR protocols and next-generation sequencing identified infection with Listeria monocytogenes (n=6), ovine herpesvirus 2 (n=7), bovine astrovirus CH13 (n=2), bovine herpesvirus 6 (n=6), bovine retrovirus CH15 (n=2), posavirus 1 (n=2), and porcine astroviruses (n=2). A retrospective questionnaire-based investigation indicated that animals' owners observed clinical signs of neurological disease in about one-third of cases with lesions, which was estimated to correspond to approximately 85 cases per year in the adult fallen cattle population in Switzerland. This estimate stands in sharp contrast to the number of cases reported to the authorities and reveals a gap in disease surveillance. Systematic neuropathological examination and follow-up molecular testing of neurologically diseased cattle could significantly enhance the efficiency of disease detection for the purposes of estimating the prevalence of endemic diseases, identifying new or re-emerging pathogens, and providing "early warnings" of disease outbreaks.

Malignant catarrhal fever: recent update

Malignant catarrhal fever (MCF) is a serious, usually fatal disease affecting many species of ungulates of the subfamily Bovinae and family Cervidae including pigs and caused by a herpesvirus under the genus Macavirus in the subfamily Gammaherpesvirinae. Ten Macaviruses have been identified to date and 6 were found to be associated with clinical MCF. Alcelaphine herpesvirus 1 (AlHV-1), which causes inapparent infection in wildebeest and ovine herpesvirus 2 (OvHV-2), which is associated with subclinical infections in sheep are the two most important herpes viruses that cause clinical wildebeest associated MCF (WA-MCF) and sheep-associated MCF (SA-MCF), respectively. The disease is characterized by accumulation of lymphocytes (predominantly CD8+ T cells) in a variety of organs, often associated with tissue necrosis. AIHV-1 can be recovered from animals, while OvHV-2 has never been recovered from affected animals, only OvHV-2 specific DNA is detected in cultured lymphoblastoid cells from infected animals. Diagnosis is normally achieved by observing the clinical signs, characteristic histopathological changes, ELISA and detection of viral DNA in the infected animals. Detection of viral DNA by PCR is becoming the method of choice for diagnosing the SA-MCF. Currently, there is no effective disease control measure. Attenuated AlHV-1 virus vaccine has been developed with varying degree of success for control of WAMCF in Africa. Separation of reservoir host from susceptible host or raising of OvHV-2 free sheep is the only solution for control of SA-MCF. In India, our group first confirmed SA-MCF in Kashmir. The present article updates current epidemiology, diagnosis, prevention and control of MCF with special reference to India.

Genetic characterization of ovine herpesvirus 2 strains involved in water buffaloes malignant catarrhal fever outbreaks in Southern Italy

Ovine herpesvirus 2 (OvHV-2) was responsible for two outbreaks of malignant catarrhal fever (MCF) on two water buffalo farms in Southern Italy. In this study, the presence of this virus in the nasal swabs from sick animals as well as in the organs of dead buffaloes was ascertained by a Real-time PCR assay. Positive samples also underwent a relative quantitative analysis of the viral DNA in them. All the dead animals had the highest relative viral quantities, while buffaloes recovering from the virus had intermediate quantities, and asymptomatic OvHV-2-positive sheep had the lowest relative quantities (as compared with the calibrator). The strains involved in the MCF outbreaks underwent genetic characterization by sequencing segments of their ORF50, ORF75 and Ov9.5 genes. The results showed that the outbreaks were caused by two specific genetic variants of OvHV-2, and that these variants exhibit nucleotide differences at the loci analysed. Sheep living in the surrounding farms, as well as sheep kept with buffaloes, were also investigated as possible transmitters of the virus. In this regard, local strategies for the control of MCF should consider separating reservoir species from susceptible animals.

Exploring the virome of cattle with non-suppurative encephalitis of unknown etiology by metagenomics

Non-suppurative encephalitis is one of the most frequent pathological diagnosis in cattle with neurological disease, but there is a gap in the knowledge on disease-associated pathogens. In order to identify viruses that are associated with non-suppurative encephalitis in cattle, we used a viral metagenomics approach on a sample set of 16 neurologically-diseased cows. We detected six virus candidates: parainfluenza virus 5 (PIV-5), bovine astrovirus CH13/NeuroS1 (BoAstV-CH13/NeuroS1), bovine polyomavirus 2 (BPyV-2 SF), ovine herpesvirus 2 (OvHV-2), bovine herpesvirus 6 (BHV-6) and a novel bovine betaretrovirus termed BoRV-CH15. In a case-control study using PCR, BoAstV-CH13 (p=0.046), BoPV-2 SF (p=0.005) and BoHV-6 (p=4.3E-05) were statistically associated with the disease. These data expand our knowledge on encephalitis-associated pathogens in cattle and point to the value of NGS in resolving complex infection scenarios in a clinical disease setting.