Priming European Sea Bass Female Broodstock Improves the Antimicrobial Immunity of Their Offspring

SIMPLE SUMMARY: Immunity is a key factor in the development of fish embryos, as they are exposed to multiple pathogens. In vertebrates, the maternal transfer of immunity influences the acquisition of immunocompetence. In this work, we demonstrate that in fish, broodstock female priming close to the spawning season improves the development of the innate immune system of their progeny. This occurs via the enhancement of several innate activities and the upregulation of the transcriptional levels of different antimicrobial peptides. Moreover, we provide evidence of the existence of the maternal transfer of immune proteins related to antimicrobial responses in European sea bass. This work also demonstrates that the use of a CP-NNV-expressing vector for priming females is safe, as the plasmid was not detected in their progeny. ABSTRACT: Acquiring immunocompetence is essential in the development of fish embryos, as they are exposed to environmental pathogens even before they are fertilized. Despite the importance of the antimicrobial function as the first line of defense against foreign microorganisms, little knowledge is available about its role in larval development. In vertebrates, transgenerational immune priming influences the acquisition of immunocompetence of specimens, regulating the selective allocation of nongenetic resources to their progeny and modulating their development. In this work, we primed teleost European sea bass broodstock females with a viral protein expression vector in order to evaluate the innate immunity development of their offspring. Several antimicrobial functions, the pattern of expression of gene coding for different antimicrobial peptides (AMPs), and their protein levels, were evaluated in eggs and larvae during development. Our data determined the presence of antimicrobial proteins of maternal origin in eggs, and that female vaccination increases antimicrobial activities and the transcription and synthesis of AMPs during larval development.