Proteomic profiling of the serological response to a chemically-inactivated nodavirus vaccine in European sea bass Dicentrarchus labrax.

The analysis of animal responses to immunization is fundamental to vaccine development, enabling the evaluation of immune responses and the elucidation of key mechanisms underlying protective immunity. Such insights are essential for advancing vaccines through clinical trial stages and regulatory approval. Furthermore, understanding the molecular signatures of approved vaccines not only deepens our knowledge of their function but also guides the rational design and improvement of future vaccines. This study aims to elucidate alterations in protein abundance patterns in the sera of European sea bass, D. labrax, following immunization with a chemically-inactivated nodavirus vaccine. The shotgun proteome comparison revealed that in vaccinated animals, compared to controls, there is a modulation of the redox balance favouring reactive oxygen species (ROS), an intricate interaction between coagulation and the immune system resulting in the lower abundance of hematopoiesis-related FLT3, and indications of functional adaptive immunity demonstrated by the lower abundance of pentraxin fusion protein-like and the over-representation of myosins. To the best of our knowledge, this study represents the inaugural investigation of the immune response in fish using a proteomics approach, employing D. labrax as the host and nodavirus as the pathogen used for vaccination and challenge.