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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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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.

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.

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.

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. [ABSTRACT FROM AUTHOR]

Simple Summary: Bovine gammaherpesvirus 6 (BoGHV6), previously known as bovine lymphotropic virus, is a member of the Macavirus genus, subfamily Gammaherpesvirinae. The role of BoGHV6 in the development of disease in ruminants is controversial. This report identified BoGHV6 in the lungs of a cow with interstitial pneumonia, while other agents associated with the development of pulmonary disease in cattle were not detected by molecular testing. These initial findings suggest that this viral pathogen may be a potential cause of pulmonary disease in cattle. Bovine gammaherpesvirus 6 (BoGHV6), previously known as bovine lymphotropic virus, is a member of the Macavirus genus, subfamily Gammaherpesvirinae. Other members of the genus Macavirus include viruses that produce malignant catarrhal fever (MCF) in mammalian hosts, collectively referred to as the MCF virus (MCFV) complex, and the porcine lymphotropic herpesvirus (PLHV). However, the current role of BoGHV6 in the development of diseases and/or disease syndromes remains uncertain and controversial. This paper investigated the participation of BoGHV6 in the development of pulmonary disease in a cow with interstitial pneumonia by histopathology and molecular testing. Tissue antigens of common viral agents of respiratory diseases and Mycoplasma bovis were not identified by immunohistochemistry. Additionally, molecular assays designed to amplify common bacterial and viral pathogens of pulmonary disease did not amplify the nucleic acids of these agents. However, a pan-PCR assay amplified the DNA of the herpesvirus polymerase gene, while the specific BoGHV6 nested-PCR assay amplified the partial fragment of the BoGHV6 polymerase gene derived from the pulmonary tissue with interstitial pneumonia. Phylogenetic analysis revealed that the BoGHV6 strain herein identified had 99.8% nucleotide (nt) sequence identity with reference strains of BoGHV6, but only 72.2–73.5% and 67.9–68.6% nt identity with reference strains of MCFV and PLHV, respectively. Consequently, these results suggest that BoGHV6 was associated with the pulmonary disease observed in this cow. [ABSTRACT FROM AUTHOR]

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 caspasedependent 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. [ABSTRACT FROM AUTHOR]

High prevalence (46 %) of a gammaherpesvirus was confirmed by molecular detection in the lungs of hunted Pyrenean chamois. The partial glycoprotein B sequence up to the DNA polymerase gene showed 96.6 % nucleotide sequence identity to the Rupicapra rupicapra gammaherpesvirus 1 and 81.5 % to ovine herpesvirus 2. This novel sequence clusters within sequences derived from the malignant catarrhal fever group of viruses, and the corresponding virus is tentatively named Rupicapra pyrenaica gammaherpesvirus 1 (RpHV-1). No specific histological lesions were associated with RpHV-1, nor were any detrimental effects on host health. The epidemiological, phylogenetic and histopathological results suggest that Pyrenean chamois is the natural host of RpHV-1. [ABSTRACT FROM AUTHOR]

Bovine gammaherpesvirus 6 (BoGHV6), formerly known as bovine lymphotropic virus, is a member of the Macavirus genus, subfamily Gammaherpesvirinae , family Herpesviridae , that was initially associated with proliferative diseases in cattle. While the Macavirus genus contains agents, including alcelaphine gammaherpesvirus 1 (AlGHV1), ovine gammaherpesvirus 2 (OvGHV2), and caprine gammaherpesvirus-2 (CpGHV2), known to cause malignant catarrhal fever (MCF), and are collectively referred to as MCF virus (MCFV) group of organisms, diseases and/or clinical syndromes have not been associated with BoGHV6 and porcine lymphotropic herpesvirus (PLHV). This report investigated the occurrence of BoGHV6 in tissues of aborted dairy fetuses known to be infected by Histophilus somni to identify possible disease patterns associated with infection by this Macavirus. A nested-PCR (nPCR) assay was used to amplify the BoGHV6 polymerase gene from multiple tissues of 13 fetuses and the cow of one of these which were derived from seven dairy herds located in three geographical regions of Brazil. Direct sequencing confirmed the results of the nPCR assays. Additionally, all fetal tissues were previously investigated for the presence of H. somni, Listeria monocytogenes, Neospora caninum, Brucella abortus, Leptospira spp., bovine alphaherpesvirus 1, and bovine viral diarrhea virus (BVDV) by PCR and/or RT-PCR assays. The nPCR assay amplified BoGHV6 DNA from fetuses of most dairy herds (85.7%; 6/7) investigated, resulting in the amplification of BoGHV6 from 76.9% (10/13) of all fetuses evaluated from two geographical and important cattle-producing regions of Brazil. Furthermore, only BoGHV6 was identified in the spleen (n = 3), myocardium, and kidney (n = 2) of five fetuses, and BoGHV6 was the only agent associated with myocarditis in one of these. Nevertheless, dual, triple, and quadruple infections (including BVDV, B. abortus , and N. caninum) were identified in fetuses that were concomitantly infected by H. somni. Phylogenetic analysis revealed that the strain herein identified has 100% nucleotide (nt) sequence identity with wild type strains of BoGHV6 circulating in ruminants from Brazil and 99.8% nt identity with the reference strain of BoGHV6 but was 72.2–73.3% and 67.4–68.2% different from members of the MCFV group and PLHV, respectively. These results demonstrated that 76.9% of the fetuses evaluated were infected by BoGHV6, most likely via vertical infection resulting in transplacental transmission. Considering that most fetuses were concomitantly infected by BoGHV6 and H. somni the real impact of this viral infection cannot be efficiently determined. However, since BoGHV6 was the only pathogen identified in the myocardium of one fetus with myocarditis by histopathology, the possible participation of this Macavirus in the etiopathogenesis of the myocardial disease observed in this fetus cannot be ignored or discarded. However, the mere amplification of BoGHV6 DNA from the myocardium is not enough to establish a definite association between cause and effect, since in situ evaluations and experimental studies would be needed to confirm this agent in the etiopathogenesis of fetal diseases and/or abortions in cattle. Consequently, additional studies are needed to determine the exact role, if any, of BoGHV6 in the development of fetal disease, and possibly fetal mortality. • BoGHV6 was identified in multiple tissues of aborted fetuses concomitantly infected by Histophilus somni. • Only BoGHV6 was identified in several organs of aborted fetuses. • Myocarditis was identified in a fetus that was infected only by BoGHV6. • BoGHV6 can be transmitted vertically via transplacental infection. • BoGHV6 should be considered a putative agent of fetal infection in cattle. [ABSTRACT FROM AUTHOR]

• Recognition of a new malignant catarrhal fever virus in big horn sheep. • The MCF virus carried by big horn sheep is closely related but distinct from OvHV-2. • We suggest referring to the MCF virus carried by bighorn sheep as ovine herpesvirus 3 (OvHV-3). The genus Macavirus of the subfamily Gammaherpesvirinae comprises two genetically distinct lineages of lymphotropic viruses. One of these lineages includes viruses that can cause malignant catarrhal fever (MCF), which are known as MCF viruses (MCFV). All MCFVs are genetically and antigenically related but carried by different hosts. In this study, we report the recognition of new MCFV carried by bighorn sheep. The virus was first identified in a bighorn sheep from Banff National Park, Alberta, Canada. Analysis of a conserved region of the viral DNA polymerase gene of the virus carried by this bighorn sheep showed 85.88% nucleotide identity to the MCFV carried by domestic sheep, ovine herpesvirus 2 (OvHV-2). Further investigation of bighorn samples obtained from animals in the US and Canada showed 98.87–100% identity to the DNA polymerase sequence of the first bighorn in the study. Phylogenetic analysis indicated that the MCFV carried by bighorn sheep is closely related but distinct from OvHV-2. Epidemiological and virulence features of the newly recognized MCFV are still unknown and warrant further investigation. Considering the current nomenclature for MCFVs, we suggest a tentative designation of ovine herpesvirus-3 (OvHV-3) for this newly identified bighorn sheep MCFV. [ABSTRACT FROM AUTHOR]