IL-18 potentiated whole blood IFN-γ assay can identify cell-mediated immune responses towards Lawsonia intracellularis in experimentally infected pigs.

Ulla Riber, Jeanne Toft Jakobsen, Henriette Cordes Hvass, Gregers Jungersen

    Research output: Contribution to conferenceConference abstract for conferenceResearch

    Abstract

    Lawsonia intracellularis is an obligate intracellular bacteria causing proliferative enteropathy (PE) in pigs. The infection causes diarrhoea, retarded growth and sudden death in pigs and is one of the most economically important diseases in the swine industry worldwide. The infection is one of the major causes of antibiotics usage in modern pig production. Diagnostic measurement of L. intracellularis infection includes detection of L. intracellularis in faecal samples by PCR, immuno-histopathology examination of intestine and measurement of Lawsonia-specific antibodies in serum. There are strong indications that cell-mediated immune responses (CMI) are important for the protection against infections with L. intracellularis and in mice models IFN-γ has been shown to play a key role in the host defence against experimental infections . In L. intracellularis infected pigs, IFN-γ is only sparsely investigated, but IFN-γ producing cells have been shown by ELISPOT in pigs experimentally infected with L. intracellularis . At National Veterinary Institute, experimental L. intracellularis infection studies have been performed and an IFN-γ assay was developed based on overnight incubation of heparin-stabilised whole blood with SDS-treated L. intracellularis (SDS-antigen) in the presence of IL-18. The produced IFN-γ was quantified by ELISA. Using this IL-18 potentiated IFN-γ assay, high levels of IFN-γ was measured from 2 weeks p.i. in pigs infected at 12 weeks of age, however, pigs infected at 5 weeks of age exhibited a much lower level of IFN-γ response. Thus, age seems to be an important parameter in measurement of IFN-γ in response to L. intracellularis infection. In the young pigs antibiotic treatment (from 3 weeks. p.i.) cleared the L. intracellularis infection. In contrast to the low response observed during the acute primary infection, these pigs mounted, after antibiotic treatment, a high antigen-specific IFN-γ response 7 weeks p.i., even when no signs of L. intracellularis infection were detected. Pigs receiving a primary L. intracellularis infection at 5 weeks of age followed by a challenge infection at 12 weeks of age showed increased or constant high levels of IFN-γ after challenge. These pigs were protected against Lawsonia re-infection in contrast to age matched challenge control pigs, which developed Lawsonia infection. Four-color flow cytometry was used to identify cells producing IFN-γ after co-incubation of PBMCs with SDS-antigen and IL-18. IFN-γ producing cells were mostly identified as CD4+, and especially CD4+CD8+ double positive T-cells also expressing CD25.
    Original languageEnglish
    Publication date2009
    Publication statusPublished - 2009
    EventElsingore Meeting : Prophylactic & Therapeutic Intervention in Host-Pathogen Interaction - Helsingør, Denmark
    Duration: 1 Jan 2009 → …
    Conference number: 8th

    Conference

    ConferenceElsingore Meeting : Prophylactic & Therapeutic Intervention in Host-Pathogen Interaction
    Number8th
    CityHelsingør, Denmark
    Period01/01/2009 → …

    Keywords

    • IFN-γ
    • Lawsonia intracellularis

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