This study aims to determine the serological profile of high-yielding dairy cows for four main viruses (bovine alphaherpesvirus 1 (BoAHV1), bovine viral diarrhea virus (BVDV), bovine parainfluenza virus 3 (BPIV3), and bovine respiratory syncytial virus (BRSV)) related to bovine respiratory disease (BRD) in cattle herds worldwide. In this survey, 497 blood serum samples were collected from non-vaccinated dairy cows without clinical respiratory signs in 39 herds in the central-eastern mesoregion of Paraná State, South Brazil. The presence of neutralizing antibodies was determined by virus neutralization (VN) tests. VN antibodies against BoAHV1, BVDV, BPIV3, and BRSV were detected in 355 (71.4%), 280 (56.3%), 481 (96.8%), and 315 (63.4%) serum samples, respectively. The frequencies of seropositive herds for BoAHV1, BVDV, BPIV3, and BRSV were 79.5 (n = 31), 82.0 (n = 32), 100 (n = 39), and 84.6% (n = 33), respectively. The frequencies of seropositive cows varied according to the type of herd management and the number of cows in the herd. The detection of VN antibodies in unvaccinated dairy cattle herds demonstrated the endemic circulation of the four viruses in the herds evaluated. For BRD prevention, it is recommended to implement a vaccination program for cows that provides passive immunity in calves and active immunity in cows.

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.

Introduction: Sheep associated-malignant catarrhal fever is a frequently fatal, lymphoproliferative, and vascular disease caused by ovine gammaherpesvirus 2 (OvGHV2), a member of the malignant catarrhal fever virus (MCFV) complex. OvGHV2-related epidemics normally have reduced morbidity with elevated lethality. Methodology: This study investigated the causes of elevated morbidity, mortality, and lethality in cattle maintained on Brachiaria grass pastures and with neurological and enteric disease syndromes from nine farms in Paraná, Southern Brazil. Results: The principal histopathological findings included necrotizing lymphocytic vasculitis, proliferative vascular lesions, and toxic cholangiohepatitis. An immunohistochemical (IHC) assay utilizing the 15A monoclonal antibody (15A-MAb), which is specific for MCFV, revealed positive intracytoplasmic immunoreactivity within the epithelial cells of the lungs, intestine, liver, and kidneys in most animals, confirming infections by MCFV. PCR detected singular infections by OvGHV2 (n = 3) and bovine gammaherpesvirus 6 BoGHV6 (n = 3) in cattle with positive intracytoplasmic immunoreactivity by the 15A-MAb IHC assay. In one animal with positive immunoreactivity to the 15A-MAb IHC assay, neither Macavirus was identified through molecular testing. Conclusions: These findings suggested that these two Macavirus were associated with the positive IHC findings. Additionally, the non-detection of OvGHV2 and BoGHV6 in the organs of one animal, despite typical vascular lesions and with positive IHC results, suggests that another Macavirus may be involved. Moreover, the identification of BoGHV6 DNA in cattle not infected by OvGHV2 but containing MCFV antigens, indicates cross-reactivity of BoGHV6 with the 15A-MAb assay. The possibe role of Bracharia on the occurrence of these infections is discussed.