Vaccination with a Lawsonia intracellularis subunit water in oil emulsion vaccine mitigated some disease parameters but failed to affect shedding.

Lawsonia intracellularis is the causative agent of ileitis in swine that manifests as slower weight gain, mild or hemorrhagic diarrhea and/or death in severe cases. As an economically important swine pathogen, development of effective vaccines is important to the swine industry. In developing a subunit vaccine with three recombinant antigens - FliC, GroEL and YopN - we wanted to identify a formulation that would produce robust immune responses that reduce disease parameters associated with Lawsonia intracellularis infection. We formulated these three antigens with four adjuvants: Montanide ISA 660 VG, Montanide Gel 02 PR, Montanide IMS 1313 VG NST, and Montanide ISA 61 VG in an immunogenicity study. Groups vaccinated with formulations including Montanide ISA 660 VG or Montanide ISA 61 VG had significantly more robust immune responses than groups vaccinated with formulations including Montanide Gel 02 PR or Montanide IMS 1313 VG NST. In the challenge study, animals vaccinated with these antigens and Montanide ISA 61 VG had reduced lesion scores, reduced lesion lengths, and increased average daily gain, but no reduction in shedding relative to the control animals. This work shows that this vaccine formulation should be considered for future study in a field and performance trial.
Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Heather Wilson reports financial support was provided by Collaborative Research Agreement. Kezia Fourie reports financial support was provided by Collaborative Research Agreement. Siew Hon Ng reports financial support was provided by Collaborative Research Agreement. Haoming Liu reports financial support was provided by Collaborative Research Agreement. Zahed Khatooni reports financial support was provided by Collaborative Research Agreement. Emil Berberov reports financial support was provided by Collaborative Research Agreement. All authors listed within the Declaration received salary support and support for the materials and supplies for the work through the Collaborative Research Agreement and no personal benefits. We have no relationships or activities to declare. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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