Protection and antibody reactivity in lumpsucker (Cyclopterus lumpus L.) following vaccination against Pasteurella sp

• Published in: Fish & shellfish immunology Vol. 95; pp. 650 - 658
• Main Authors: Ellul, Rebecca Marie, Bulla, Jan, Brudal, Espen, Colquhoun, Duncan, Wergeland, Heidrun, Rønneseth, Anita
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.12.2019
• Subjects: Adaptive Immunity; Animals; Antibodies; Antibodies, Bacterial - blood; Antibodies, Bacterial - immunology; Bacterial Vaccines - administration & dosage; Bacterial Vaccines - immunology; Challenge; Fish Diseases - immunology; Fish Diseases - microbiology; Fish Diseases - prevention & control; Head Kidney - immunology; Head Kidney - microbiology; Immunology; Infection; Lumpsucker; Pasteurella; Pasteurella Infections - prevention & control; Pasteurella Infections - veterinary; Pasteurellosis; Pathology; Perciformes - immunology; Perciformes - microbiology; Vaccination; Infection; Pathology; Immunology; Vaccination; Antibodies; Lumpsucker; Pasteurellosis; Challenge
• ISSN: 1050-4648; 1095-9947
• DOI: 10.1016/j.fsi.2019.11.016

Two monovalent vaccines against pasteurellosis were developed and tested for efficacy using a previously established bath challenge model. High levels of specific antibodies were detected following vaccination. While the vaccine efficacy trial indicated that some level of protection was obtained, high mortality was still observed. qPCR analysis of head kidney tissues from surviving fish post challenge showed no difference in bacterial numbers in vaccinated and non-vaccinated fish. Clinical symptoms observed in moribund and diseased fish included white spots on the skin and around the eyes, frayed fins and redness around the mouth and fin bases. Despite production of specific antibodies, the protection against experimental challenge was relatively weak. A reason for this could potentially be that the specific antibodies produced are not alone enough to provide complete protection against pasteurellosis in lumpsuckers. Confocal and scanning electron microscopy of head kidney leucocytes exposed to Pasteurella sp. in vitro gave indications of the interactions between the pathogen and leucocytes. The results indicate that parts of the immune system other than humoral antibodies could be important for protection against pasteurellosis. Our combined results highlight the need for further work on host-pathogen interaction between Pasteurella sp. and lumpsuckers. •Specific antibodies were generated following vaccination using Pasteurella sp.•Testing vaccines by bath challenge showed no protection was observed.•Immunofluorescence and SEM indicated Pasteurella sp. may be found within leucocytes.•Serum antibody reactivity to Pasteurella sp. antigens on immunoblots is limited.