ORIGINAL RESEARCH article
Front. Immunol.
Sec. Comparative Immunology
Volume 16 - 2025 | doi: 10.3389/fimmu.2025.1579541
Protective IgM-mediated immunity against Vibrio anguillarum in Atlantic cod with evolutionary losses of mhc class II and cd4
Provisionally accepted
Finn-Eirik Johansen1*
Alexandra Jonsson1
Adrián Lopez Porras1
Simen Foyn Nørstebø2Naomi Croft Guslund1
Rune Henning Sørum2
Shuo-Wang Qiao1- 1University of Oslo, Oslo, Norway
- 2Norwegian University of Life Sciences, As, Akershus, Norway
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The unique adaptive immune system of the Atlantic cod (Gadus morhua), with genetic loss of the mhc class II and cd4, poses questions about the protective role of specific antibodies in this species. We investigate the IgM response against Vibrio anguillarum, a common pathogen in aquaculture. Juvenile Atlantic cod were bath-immunized with formalin-fixed V. anguillarum serotype O2a. Vaccinated cod were fully protected against lethal vibriosis when challenged by immersion with serotype O2a and partially protected against challenge by serotype O2b. Serum IgM from immunized cod reacted specifically with V. anguillarum O2a in ELISA, with some crossreactivity towards the O2b serotype. Bath-immunized cod were also protected against intracelomic challenge with V. anguillarum O2a, supporting induction of systemic immunity by bath vaccination.Passive transfer experiments were conducted to evaluate the protective efficacy of IgM. Naive cod that received total serum or purified IgM from immunized donors were protected against lethal vibriosis; whereas, naive cod that received naive serum were not protected. Western blotting revealed that these protective antibodies recognized a proteinase K sensitive antigen rather than lipopolysaccharides (LPS). These insights enhance our understanding of cod immunity and provide guidance for developing future vaccination strategies in aquaculture.
Keywords: Atlantic cod, vibrio anguillarum, IgM antibodies, antibody response, Adaptive Immunity, Aquaculture immunology
Received: 19 Feb 2025; Accepted: 12 May 2025.
Copyright: © 2025 Johansen, Jonsson, Lopez Porras, Foyn Nørstebø, Guslund, Sørum and Qiao. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Finn-Eirik Johansen, University of Oslo, Oslo, Norway
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