RESUMO
Introduction: Bovine leukaemia virus (BLV) is a Deltaretrovirus responsible for enzootic bovine leukosis, the most common neoplastic disease of cattle. It deregulates the immune system, favouring secondary infections and changes in the blood and lymphatic tissues. Blood homeostasis depends on functional haematopoietic stem cells (HSCs). Bone marrow is populated by these cells, which express CD34+ and CD35+ surface antigens and produce and release cytokines involved in the maintenance of haematopoiesis. The aim of the study was determination of the profile of cytokine production by CD34+ stem cells of cattle naturally infected with BLV. Material and Methods: The HSCs were generated from the blood and lymphoid organs of cows infected with BLV and healthy control cows with immunomagnetic separation and anti-CD34+ monoclonal antibodies. Isolated CD34+ cells were cultivated for two weeks with interleukin (IL)-4 and granulocyte-macrophage colony-stimulating factor. The levels of IL-6, IL-10, IL-12p40, IL-12p70, interferon gamma (IFN-γ) and tumour necrosis factor alpha (TNF-α) were determined in culture fluid by flow cytometry. Results: The expression of IL-6, IL-12p70 and TNF-α in blood HSCs was higher in BLV+ cows than in the control animals. In bone marrow HSCs of infected cows, IL-12, TNF-α and IFN-γ were more concentrated, but in these cows' spleen HSCs only expression of IL-10 was elevated. In HSCs isolated from the lymph nodes of leukaemic cows, only TNF-α secretion was lower than in control cows, the other cytokines being more potently secreted. Conclusion: Infection with BLV caused statistically significant differences in cytokine expression by HSC CD34+ cells.
RESUMO
Introduction: Bovine leukaemia virus (BLV) is the retroviral causative agent of enzootic bovine leukosis, the most common neoplastic disease of cattle and a serious problem worldwide. Its diagnosis is commonly by tests for antibodies recognising the p24 capsid protein and structural glycoprotein (gp) 51. With flow cytometry recently having come to veterinary immunology, applications for it may now include BLV. The study determined BLV gp51 expression in blood and milk lymphocytes of naturally infected cows by flow cytometry. Material and Methods: Nineteen Polish Black and White Lowland breed cows aged 4-9 years and naturally infected with BLV and ten uninfected counterparts had blood and milk sampled and cultured. The immunological status of the animals was confirmed with ELISA and PCR. Dual-colour flow cytometry analysis was performed with specific monoclonal antibodies for lymphocyte cluster of differentiation (CD) markers and gp51 viral envelope protein and conjugates labelled with fluorescein isothiocyanate or phycoerythrin. Bovine leukaemia virus gp51 was confirmed in lymphocytes by immunofluorescence with anti-gp51 monoclonal antibodies. Results: The gp51 antigen was detected in blood and milk lymphocytes of infected cows, but the percentage of cells expressing it in milk was much lower than in blood. A depleted number of CD4+ lymphocytes, an augmented number of CD8+ lymphocytes, a lower ratio of CD4+ to CD8+ and a proliferation of CD19+ immunoglobulin M+ cells were also found. Conclusion: These proliferated cells were immature, gave no sign of a tendency to differentiation and were characterised by prolonged vitality.
RESUMO
Mycoplasma bovis is a primary infectious agent of many disorders in cattle including bovine respiratory disease. No commercial vaccines against M. bovis are available in Europe. The immune response of calves to three saponin-based adjuvants combined with a field Polish M. bovis strain was evaluated. Four groups of six calves each were injected subcutaneously with the M. bovis strain combined with either saponin, saponin + Emulsigen®, saponin + Emulsigen® + alphatocopherol acetate, or with phosphate-buffered saline as control group. Blood and nasal swab samples were collected up to day 84 post injection. All formulations effectively stimulated the humoral and the cellular immune response of the calves, but the course of the response depended on the adjuvant formulation. These immunological data provide additional information supporting the findings of previous M. bovis saponin and Emulsigen® vaccine challenge studies to facilitate the development of successful M. bovis vaccines.
