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Sheep-associated malignant catarrhal fever (SA-MCF) is a severe, frequently fatal, lymphoproliferative disease that affects a wide variety of ruminants and is caused by ovine gammaherpesvirus 2 (OvHV-2), a member of the MCF virus (MCFV) complex. The typical clinical manifestations of SA-MCF are well known and easily recognized by veterinarians, resulting in clinical diagnosis of MCF when characteristic clinical signs are present. This article describes the findings observed in cattle infected with OvHV-2 but without typical clinical manifestations of SA-MCF. Three calves with episodes of diarrhea before death and a yearling that died suddenly were investigated. Gross alterations were not suggestive of SA-MCF. Histopathology revealed a combination of proliferating vascular lesions (PVLs) and necrotizing vasculitis in three animals (two calves and the yearling); with PVLs being identified only at the carotid rete mirabile of two calves infected with OvHV-2. Additional significant histopathologic lesions included atrophic enteritis, portal lymphocytic hepatitis, interstitial pneumonia, suppurative bacterial bronchopneumonia, and pulmonary hemorrhage. An immunohistochemical assay designed to identify only antigens of MCFV revealed, positive, intralesional, intracytoplasmic immunoreactivity within epithelial cells of multiple tissues of all animals with PVLs. PCR assays amplified OvHV-2 DNA from multiple tissues of the animals that contained MCFV proteins, confirming the MCFV identified as OvHV-2. Additionally, bovine coronavirus (BCoV) nucleic acids were amplified from tissues of all animals, including the animal not infected by OvHV-2. Collectively, these findings confirmed the participation of OvHV-2 in the development of the disease patterns observed in these animals that were concomitantly infected by BCoV and provide additional confirmation that cattle can be subclinically infected with OvHV-2. Consequently, the real occurrence of OvHV-2-related disease may be more elevated than reported, since asymptomatic or subclinically infected animals are not likely to be investigated for OvHV-2. Furthermore, PVLs should be included as possible histologic indicators of OvHV-2-related diseases in ruminants.

All descriptions of infectious diseases affecting otters were published in the Northern Hemisphere, with no occurrence identified in neotropical otters ( Lontra longicaudis ). Consequently, a retrospective histopathological study using archival tissue samples from six free-living neotropical otters was done to investigate the possible occurrence of disease patterns associated with common viral infectious disease agents of the domestic dogs. Immunohistochemical (IHC) assays were designed to identify intralesional tissue antigens of canine distemper virus (CDV), and canine adenovirus-1 (CAdV-1) and canine adenovirus-2 (CAdV-2). The most frequent histopathological patterns diagnosed were interstitial pneumonia (83.33%; 6/5) and hepatocellular vacuolar degeneration (50%; 3/6). IHC identified intralesional intracytoplasmic immunoreactivity to CDV antigens in all otters evaluated, with positive immunolabeling occurring within epithelial cells of the lungs, stomach, kidneys, and liver, and skin. Intracytoplasmic CAdV-2 antigens were identified within epithelial cells of the peribronchial glands in four otters with interstitial pneumonia. These findings resulted in singular and simultaneous infections in these neotropical otters, represented the first report of concomitant infections by CDV and CAdV-2 in free-living neotropical otters from the Southern Hemisphere, and suggested that this mammalian species is susceptible to infections by viral disease agents common to the domestic dogs and may develop similar histopathologic disease patterns.

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.

This study investigated the occurrence of selected pathogens of bovine respiratory disease in fetal pulmonary tissue of cattle and associated these with patterns of disease. Fetal pulmonary (n = 37) tissues were evaluated by histopathology; immunohistochemical assays identified intralesional antigens of bovine alphaherpesvirus 1 (BoAHV1), bovine viral diarrhea virus (BVDV), bovine parainfluenza virus 3 (BPIV-3), bovine respiratory syncytial virus (BRSV), and Mycoplasma bovis. Molecular assays were performed to amplify reproductive disease pathogens and bovine gammaherpesvirus 6 (BoGHV6) from 12 lungs. The 2 patterns of pulmonary diseases were interstitial pneumonia (12/37) and suppurative bronchopneumonia (1/37). The frequency of the intralesional antigens identified was BRSV (16.2%; 6/37), BVDV (13.5%; 5/37), BoAHV1 (8.1%; 3/37), M. bovis (5.4%; 2/37), and BPIV-3 (2.7%; 1/37). Interstitial pneumonia was associated with BRSV (n = 3), BoAHV1 (n = 3), and BVDV (n = 2); suppurative bronchopneumonia contained a Gram-positive bacterium and BVDV and BRSV. Reproductive pathogens detected included Leptospira spp., (n = 3), BVDV, Neospora caninum, and Brucella abortus (n = 2). BoGHV6 DNA was identified in the lungs of two fetuses with interstitial pneumonia. These findings suggest that these fetuses were infected transplacentally by several pathogens. The role of some of these pathogens herein identified must be further elucidated in the possible participation of fetal disease.

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.