Bovine respiratory syncytial virus (BRSV) is a major respiratory pathogen in cattle and is relevant to the livestock industry worldwide. BRSV is most severe in young calves and is often associated with stressful management events. The disease is responsible for economic losses due to lower productivity, morbidity, mortality, and prevention and treatment costs. As members of the same genus, bovine and human RSV share a high degree of homology and are similar in terms of their genomes, transmission, clinical signs, and epidemiology. This overlap presents an opportunity for One Health approaches and translational studies, with dual benefits; however, there is still a relative lack of studies focused on BRSV, and the continued search for improved prophylaxis highlights the need for a deeper understanding of its immunological features. BRSV employs different host-immunity-escaping mechanisms that interfere with effective long-term memory responses to current vaccines and natural infections. This review presents an updated description of BRSV’s immunity processes, such as the PRRs and signaling pathways involved in BRSV infection, aspects of its pathogeny, and the evading mechanisms developed by the virus to thwart the immune response.

Bovine serum has been widely used as a universal supplement in culture media and other applications, including the manufacture of biological products and the production of synthetic meat. Currently, commercial bovine serum is tested for possible viral contaminants following regional guidelines. Regulatory agencies’ established tests focused on detecting selected animal origin viruses and are based on virus isolation, immunofluorescence, and hemadsorption assays. However, these tests may fail to detect new or emerging viruses in biological products. High-throughput sequencing is a powerful option since no prior knowledge of the viral targets is required. In the present study, we evaluate the virome of seven commercial batches of bovine serum from Mexico (one batch), New Zealand (two batches), and the United States (four batches) using a specific preparation and enrichment method for pooled samples and sequencing using an Illumina platform. A variety of circular replicase-encoding single-stranded (CRESS) DNA families (Genomoviridae, Circoviridae, and Smacoviridae) was identified. Additionally, CrAssphage, a recently discovered group of bacteriophage correlated with fecal contamination, was identified in 85% of the tested batches. Furthermore, sequences representing viral families with single-stranded DNA (Parvoviridae), double-stranded DNA (Polyomaviridae and Adenoviridae), single-stranded RNA (Flaviviridae, Picornaviridae, and Retroviridae), and double-stranded RNA (Reoviridae) were identified. These results support that high-throughput sequencing associated with viral enrichment is a robust tool and should be considered an additional layer of safety when testing pooled biologicals to detect viral contaminants overlooked by the current testing protocols.

Flavonoids, plant-derived compounds widely recognized for their antioxidant, anti-inflammatory, and anticancer properties, also exhibit significant antiviral effects against various animal viruses. This review highlights the promising antiviral mechanisms of flavonoids, which include disrupting viral replication, blocking cell entry, and modulating immune responses. Notably, flavonoids like quercetin, kaempferol, and genistein have been shown to effectively inhibit viruses of veterinary importance, such as African Swine Fever Virus (ASFV), Porcine Epidemic Diarrhea Virus (PEDV), and Infectious Bronchitis Virus (IBV), among others. Although most studies demonstrate efficacy in vitro, the limited in vivo research underscores the need to further explore flavonoids' antiviral potential in real-world applications. The immunomodulatory effects observed in some cases, where flavonoids regulate cytokine expression and reduce inflammation, suggest a dual action that could benefit both antiviral and anti-inflammatory responses. This body of research suggests that flavonoids could provide an option for managing animal viral infections. Yet, standardized methodologies and more in vivo studies are needed to validate these findings for veterinary use.

House flies (Musca domestica) are often present in swine farms worldwide. These flies utilize animal secretions and waste as a food source. House flies may harbor and transport microbes and pathogens acting as mechanical vectors for diseases. Senecavirus A (SVA) infection in pigs occurs via oronasal route, and animals shed high virus titers to the environment. Additionally, SVA possesses increased environmental resistance. Due to these reasons, we investigated the tenacity of SVA in house flies. Five groups of flies, each composed of ten females and ten males, were exposed to SVA, titer of 10^9.3 tissue culture infectious dose (TCID₅₀/mL). Groups of male and female flies were collected at 0, 6, 12, 24, and 48 h post-exposure. For comparison purposes, groups of flies were exposed to Swinepox virus (SwPV). Infectious SVA was identified in all tested groups. Successful isolation of SVA demonstrated the titers varied between 10^6.8 and 10^2.8 TCID₅₀/mL in female groups and varied from 10^5.85 to 10^3.8 TCID₅₀/mL in male groups. In contrast, infectious SwPV was only detected in the female group at 6 h. The significant SVA infectious titer for prolonged periods of time, up to 48 h, indicates a potential role of flies in SVA transmission.

Bovine viral diarrhea virus (BVDV) induces immunosuppression and thymus depletion in calves. This study explores the impact of prior BVDV-2 exposure on the subsequent immune response to influenza D virus (IDV). Twenty 3-week-old calves were divided into four groups. Calves in G1 and G3 were mock-treated on day 0, while calves in G2 and G4 received BVDV. Calves in G1 (mock) and G2 (BVDV) were necropsied on day 13 post-infection. IDV was inoculated on day 21 in G3 calves (mock + IDV) and G4 (BVDV + IDV) and necropsy was conducted on day 42. Pre-exposed BVDV calves exhibited prolonged and increased IDV shedding in nasal secretions. An approximate 50% reduction in the thymus was observed in acutely infected BVDV calves (G2) compared to controls (G1). On day 42, thymus depletion was observed in two calves in G4, while three had normal weight. BVDV-2-exposed calves had impaired CD8 T cell proliferation after IDV recall stimulation, and the α/β T cell impairment was particularly evident in those with persistent thymic atrophy. Conversely, no difference in antibody levels against IDV was noted. BVDV-induced thymus depletion varied from transient to persistent. Persistent thymus atrophy was correlated with weaker T cell proliferation, suggesting correlation between persistent thymus atrophy and impaired T cell immune response to subsequent infections.

The present study aimed to assess the CD4, CD8 and γδ blood levels for Curraleiro Pé-duro, as well as the specific IFN-γ response after BCG vaccination using flow cytometry. The specific immune response against BCG was also evaluated by tuberculin skin test, performed before and 45 days after the vaccination. For comparison purposes, the same parameters were investigated on Nellore calves, an exotic bovine with resistance previously demonstrated. Naturally, Curraleiro Pé-duro animals had greater levels of CD4, CD8 and γδ lymphocytes (p<0.05). In response to vaccine, Curraleiro Pé-duro showed greater ability to respond specifically to BCG, generating resistance profile (Th1), evidenced by greater number of antigen specific CD4+ cells producing IFN-γ (p<0.05) and also higher tuberculin skin test reaction (p<0.05). Additionally, vaccinated Curraleiro Pé-duro calves had higher CD4 cells numbers than both Nellore control (p<0.05) and vaccinated groups (p<0.05). Curraleiro Pé-duro calves' higher basal lymphocytes blood level and stronger response in both IFN-γ and tuberculin skin test parameters probably play a positive role on protection/resistance to Mycobacterium bovis