Changes in peripheral blood leucocyte counts and subpopulations after experimental infection with BVDV and/or Mannheimia haemolytica.
ABSTRACT Leucocyte counts and subpopulations were studied in peripheral blood from calves experimentally infected in the respiratory tract with either bovine virus diarrhoea virus (BVDV) or Mannheimia haemolytica (Mh), or with a combination of both agents (BVDV/Mh). A non-inoculated control group was included. Peripheral blood samples were obtained for total leucocyte counts, and for neutrophil, lymphocyte and monocyte counts. The numbers of blood lymphocytes expressing the surface antigens CD4, CD8, WC1, B and IL-2R were analysed using flow cytometry. The results showed that BVDV inoculation induced a significant decrease in total leucocyte counts and in neutrophil and lymphocyte numbers, while Mh inoculation induced significant increases in total leucocyte counts and neutrophils, while the lymphocyte count decreased. In the BVDV/Mh group, the total leucocyte count and the lymphocyte numbers decreased significantly. In this group, the lymphocyte numbers remained on a very low level throughout the rest of the study. The numbers of CD4+, CD8+ and WC1+ lymphocytes decreased significantly compared with before inoculations mainly in the BVDV and BVDV/Mh groups. The drops were most pronounced in the BVDV/Mh group. The numbers of B+ lymphocytes and IL-2R+ cells did not change significantly.
- SourceAvailable from: Pedro Jose Sanchez-Cordon[Show abstract] [Hide abstract]
ABSTRACT: Acute infections with bovine viral diarrhoea virus (BVDV), a major pathogen of cattle, are often asymptomatic or produce only mild clinical symptoms. However, they may play an important role in the bovine respiratory disease complex by exerting a marked immunosuppressive effect, as a result of the death of the immunocompetent cell populations involved in controlling innate and adaptive immune responses, together with a marked reduction of both cytokine expression and co-stimulatory molecule synthesis. Although experimental research and field studies have shown that acute BVDV infection enhances susceptibility to secondary infection, the precise mechanism involved in BVDV-induced immunosuppression remains unclear. The present study is aimed at measuring a range of blood parameters in a single group of fourteen calves infected with non-cytopathic BVDV-1. Focus has been put on those related to the cell-mediated immune response just as leucocyte populations and lymphocyte subpopulations, serum concentrations of cytokines (IL-1β, TNF-α, IFN-γ, IL-12, IL-4 and IL-10) and acute phase proteins [haptoglobin, serum amyloid A (SAA), fibrinogen and albumin], as well as BVDV-specific antibodies and viremia. After non-cytopathic BVDV-1 infection, clinical signs intensity was never more than moderate coinciding with the presence of viremia and leucocyte and lymphocyte depletion. An early increase in TNF-α, IFN-γ and IL-12 levels in contrast to IL-1β was observed in line with a raise in haptoglobin and SAA levels on the latest days of the study. As regards IL-4 levels, no evidence was found of any changes. However, a slight increase in IL-10 was observed, matching up the TNF-α decline during the acute phase response. These findings would help to increase our knowledge of the immune mechanisms involved in acute infection with non-cytopathic BVDV-1 strains, suggesting the existence of a clear tendency towards a type 1 immune response, thereby enhancing resistance against viral infections.Transboundary and Emerging Diseases 09/2012; · 2.10 Impact Factor
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ABSTRACT: Atypical bovine pestiviruses related to bovine viral diarrhoea virus (BVDV) have recently been detected in cattle from South America, Asia and Europe. The purpose of this study was to compare the clinical and virological aspects of dual infection with BVDV-1 (Horton 916) and an Asian atypical bovine pestivirus (Th/04_KhonKaen) in naïve calves, in comparison to single infections. Milder clinical signs were observed in the animals infected with single Th/04_KhonKaen strain. Leukocytopenia and lymphocytopenia were observed in all infected groups at a similar level which correlated with the onset of viraemia. Co-infection with both viruses led to prolonged fever in comparison to single strain inoculated groups and simultaneous replication of concurrent viruses in blood and in the upper respiratory tract. Following the infections all the calves seroconverted against homologous strains. Atypical pestiviruses pose a serious threat to livestock health and BVDV eradication, since they may have the potential to be widely spread in cattle populations without being detected and differentiated from other BVDV infections.Comparative immunology, microbiology and infectious diseases 04/2012; 35(4):381-90. · 2.99 Impact Factor