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Research article2001Peer reviewed

Effects of an experimental infection with Actinobacillus pleuropneumoniae on the interferon-alpha and interleukin-6 producing capacity of porcine peripheral blood mononuclear cells stimulated with bacteria, virus or plasmid DNA

Johansson, E; Fossum, C; Fuxler, L; Wallgren, P


The effect of a bacterial infection on interferon-alpha (IFN-alpha) and interleukin-6 (IL-6) production by porcine cells was studied in specific pathogen-free (SPF) pigs, infected intranasally with Actinobacillus pleuropneumoniae serotype 2. Three experimental groups of five pigs were used: infected non-treated pigs, infected pigs that were treated with enrofloxacin at disease onset, and non-infected, non-treated control pigs. Blood samples were collected from all pigs on the day of infection and on days 1, 4. 7, 13 and 17 post-infection. Sera were analysed for presence of antibodies to A. pleuropneumoniae and for the cytokines IL-6 and IFN-alpha. Ability to produce these cytokines was tested in vitro using whole blood cultures stimulated with inactivated virus (Aujeszky's disease virus infected porcine kidney cells (ADV/PK-15)), inactivated bacteria (A. pleuropneumoniae) or bacterial plasmid (pcDNA3). All cytokine inducers were used neat or pre-incubated with the transfectious agent lipofectin. IL-6 appeared in the serum of all infected nontreated animals but no IFN-alpha was found in the serum of any of the experimental pigs. Accordingly, the bacteria induced a substantial IL-6 but hardly any IFN-alpha production when tested in vitro. However, following incubation with lipofectin. the inactivated bacteria as well as pcDNA3 became efficient inducers of IFN-alpha in whole blood cultures. The increased TFN-alpha production, previously recorded in vitro during the acute phase of infection with A. pleuropneumoniae, was confirmed using lipofected plasmid DNA and it was indicated that leukocytes obtained from infected but apparently cured animals also exhibited an increased production of IFN-alpha. Thus, even mild/subclinical bacterial infections may affect cytokine production in pigs. (C) 2001 Elsevier Science B.V. All rights reserved.


Actinobacillus pleuropneumoniae; interferon-alpha; CpG-DNA; porcine; interleukin-6

Published in

Veterinary Microbiology
2001, Volume: 79, number: 2, pages: 171-182

      SLU Authors

    • Fossum, Caroline

      • Department of Veterinary Microbiology, Swedish University of Agricultural Sciences
      • Fuxler, Lisbeth

        • Department of Veterinary Microbiology, Swedish University of Agricultural Sciences

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