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/ß 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.

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.

Evaluation of Ultraviolet Type C Radiation in Inactivating Relevant Veterinary Viruses on Experimentally Contaminated Surfaces.

Many swine farms employ UVC treatment in employees' personal belongings and small tools entering farms as part of the biosecurity protocol to decrease the risk of pathogen introduction into the operation. However, the UVC efficacy in some veterinary viruses is not fully evaluated. This study evaluated the efficacy of ultraviolet type C (UVC) radiation in inactivating seven relevant veterinary viruses: Swine Poxvirus (SwPV), Porcine Reproductive and Respiratory Syndrome Virus (PRRSV), Porcine Epidemic Diarrhea Virus (PEDV), Swine Influenza Virus (SIV), Bovine Viral Diarrhea Virus (BVDV), Porcine Parvovirus (PPV), and Senecavirus A (SVA). The experimentally contaminated materials included polystyrene and filter paper. The samples were exposed to UVC for 5 min (total dose of 360 mJ/cm2). The UVC treatment caused a decrease over 4 log10 in SwPV titer on the polystyrene surface, whereas it consistently reduced about 5 log10 in PPV and SVA samples. No viable virus was recovered from PRRSV, PEDV, SIV, and BVDV samples. In filter paper, conversely, the efficacy was reduced. This study provides essential information on the inactivation effectiveness of a specific dose of UVC on important veterinary viruses, further supporting the rational application and strategic guidance for UVC radiation use to disinfect materials.

Prolonged Viability of Senecavirus A in Exposed House Flies (Musca domestica).

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 109.3 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 106.8 and 102.8 TCID50/mL in female groups and varied from 105.85 to 103.8 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.

Cellular immune response of Curraleiro Pé-duro and Nellore calves following Mycobacterium bovis-BCG vaccination / Resposta imune celular de bezerros Curraleiro Pé-duro e Nelore após vacinação com Mycobacterium bovis-BCG

The present study aimed to assess the CD4, CD8 and Gamma delta T cells 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 Gamma delta 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.

O presente estudo teve como objetivo avaliar níveis sanguíneos de células CD4, CD8 e células T gama-delta no sangue periférico de bezerros Curraleiro Pé-Duro, bem como a produção específica de IFN-γ por essas células em resposta à vacinação com BCG, através de citometria de fluxo. A resposta imune específica contra BCG também foi avaliada por teste tuberculínico, realizado antes e 45 dias após a vacinação. Para fins de comparação, os mesmos parâmetros foram investigados em bezerros da raça Nelore, uma raça bovina exótica com resistência demonstrado anteriormente. Naturalmente, animais da raça Curraleiro Pé-Duro apresentaram maiores níveis de CD4, CD8 e linfócitos gama-delta. Em resposta a vacina, Curraleiro Pé-duro mostrou maior capacidade de responder especificamente ao BCG, gerando perfil de resistência (Th1), evidenciado pelo maior número de células CD4+ específicas produtoras de IFN-γ e maior reação cutânea a por tuberculina. Os maiores níveis basais de linfócitos, maior produção de IFN-γ e reação cutânea à prova tuberculínica provavelmente desempenham um papel positivo na proteção/resistência ao Mycobacterium tuberculosis.