Immune responses to influenza D virus in calves previously infected with bovine viral diarrhea virus 2

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.Veterinary PathobiologyDean of Veterinary Medicin

Viability of Veterinary-Relevant Viruses in Decomposing Tissues over a 90-Day Period Using an In-Vitro System

Depopulation is frequently employed during outbreaks of high-impact animal diseases. Security breaches in sites managing mortality may jeopardize pathogen control efforts as infected carcasses can serve as an infection source. This study evaluated the viability and nucleic acid detection of veterinary-relevant viruses or their surrogates in decomposing tissues. The used viruses were: Senecavirus A1 (SVA), feline calicivirus (FCV), bovine viral diarrhea virus (BVDV), porcine epidemic diarrhea virus (PEDV), bovine alphaherpesvirus 1 (BoHV-1), and swinepox virus (SwPV). Viruses were spiked in three decomposing tissues (swine bone marrow and spleen, and bovine bone marrow) and maintained for 90 days. Samples were kept under two temperature conditions resembling the average soil temperature in central Oklahoma, US, during the winter and summer (5.5 °C and 29.4 °C). At 5.5 °C, SVA and FCV remained viable over the 90 days of the study, followed by BVDV (75 days), BoHV-1 and SwPV (60 days), and PEDV (10 days). At 29.4 °C, SVA remained viable for 45 days, followed by BVDV and BoHV-1 (14 days). SwPV was viable for 10 days, whereas FCV and PEDV were viable for 5 days. Overall, viral nucleic acid detection was not significantly altered during the study. These findings support decision-making and risk management in sites overseeing animal mortality

Clinical and virological characteristics of calves experimentally infected with a Brazilian isolate of bovine viral diarrhea virus type 1a

ABSTRACT: To study the pathogenicity of the Brazilian bovine viral diarrhea virus (BVDV) type 1a 241.10 isolate, four calves were intranasally inoculated with a viral suspension containing 107.2 TCID50 mL-1. One calf was left uninoculated and kept in contact with the other calves to investigate viral transmissibility. After inoculation, the animals were monitored daily for clinical signs of infection. The presence of the virus in the blood and nasal secretions was confirmed by virus isolation in cell culture. White blood cells were quantified prior to and every 3 days after infection, and the presence of antibodies was checked every 7 days, starting at day 0 until day 42 post-inoculation (pi). After infection, nasal and ocular serous secretions were observed between days 1 and 5 pi, along with a mild cough from days 2 to 4 pi; however, no severe clinical signs were present. Body temperature was slightly elevated between days 4 and 6 pi. The control calf did not develop any of the signs observed in the infected animals. Cell culture-mediated virus isolation confirmed viremia between days 4 and 8 pi and the presence of the virus in the nasal secretions between days 1 and 10 pi. All infected animals showed a decrease in white blood cell count. Antibodies could be detected from day 14 pi, and these levels remained high until day 35 pi. The control calf had no viremia, viral presence in nasal secretions, or positive serology, indicating the absence of viral transmission. Thus, isolate BVDV 1a 241.10 has low pathogenicity and transmissibility but retains immunosuppressive capacity