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 susceptible mammalian hosts worldwide. OvGHV2 may produce typical clinical manifestations of SA-MCF or subclinical infections. Additionally, OvGHV2 is associated with cutaneous lesions in ruminants, with few documented reports of this unusual manifestation worldwide. This paper presents the pathological, immunohistochemical (IHC), and molecular findings observed in outbreaks of OvGHV2-related skin infections in dairy cattle from Southern Brazil. Cutaneous scrapings (n = 35) and biopsies (n = 6) were obtained from dairy cows derived from three farms. All cows (n = 35) developed widespread, ulcerative to scaly and erythematous skin lesions, and had no contact with sheep or goats. The biopsies were evaluated for histopathological diagnosis and then used in IHC analyses designed to detect malignant catarrhal fever virus (MCFV) antigens and to evaluate the inflammatory response. All scrapings and biopsies were used in PCR assays to amplify OvGHV2. Additionally, all biopsies were used in PCR assays to detect bovine gammaherpesvirus 6 (BoGHV6), bovine alphaherpesvirus 1 (BoAHV1), and poxvirus. Histopathology revealed chronic folliculitis in all biopsies. IHC detected intralesional, intracytoplasmic MCFV antigens in most (83.3%; 5/6) of the cutaneous lesions with folliculitis. These skin lesions showed a strong T-cell response, macrophage clusters, and caspase-positive follicular keratinocytes. OvGHV2 DNA was detected in 66.7% (4/6) of the cutaneous biopsies that contained MCFV antigens and in 8.6% (3/35) of the cutaneous scrapings. The DNA of BoGHV6, BoAHV1, and Poxvirus was not amplified from any of the cutaneous biopsies. These findings demonstrated that OvGHV2 was associated with the cutaneous lesions in dairy cows at these farms and represent the first description of OvGHV2-related skin disease in ruminants from Brazil and the entire Latin America. A review of previous cases of skin lesions associated with infections by OvGHV2 revealed that most cases had a histological diagnosis of folliculitis, suggesting that folliculitis may be associated with OvGHV2-related skin infections. Additionally, this investigation contrasts all previous reports of OvGHV2-related skin disease in ruminants, since the infected cows herein identified were not reared concomitantly or within proximity of the asymptomatic reservoir host. Furthermore, the possible form of OvGHV2 dissemination to the susceptible cows during this study is discussed.

Neonatal diarrhea remains a significant threat to piglet health, resulting in substantial economic losses worldwide. Among the viral pathogens associated with this condition, rotavirus (RV) has been extensively reported in Brazil; however, lineage-level classification of circulating strains remains limited. This study aimed to characterize G and P genotypes of porcine RV field strains associated with diarrhea in piglets in Southern Brazil. A total of 10 fecal samples were collected by field veterinarian from diarrheic suckling piglets aged 1 to 14 days and analyzed by RT-PCR for the detection of RV species A, B, C, and H. RV species A (RVA) was detected in 90% (9/10) of the samples, while no other RV species were identified. Genotyping based on the VP7 and VP4 genes revealed a single G3P[6] genotype combination in all RVA-positive samples. Nucleotide (nt) and deduced amino acid (aa) sequence analysis revealed high genetic similarity among strains, with values of up to 99.3% for nt and 98.0% for aa of the VP7 gene and 100% for the VP4 gene (nt and aa). Phylogenetic analysis indicated that the VP7 sequences clustered with Brazilian G3 strains, forming a distinct group consistent with a novel lineage (putative G3-XII), whereas VP4 sequences supported a new sublineage (putative P[6]-Ig). These findings demonstrate low genetic variability of RVA field strains in this neonatal diarrhea outbreak, suggesting the circulation of a single viral population. They also emphasize the importance of continuous molecular surveillance to gain a deeper understanding of viral evolution and transmission dynamics in swine populations.