Advancements in Vaccinology Against Infectious Hematopoietic Necrosis Virus (IHNV): From Traditional Methods to Next-Generation Strategies

Background: Infectious hematopoietic necrosis virus (IHNV), a rhabdovirus classified within the genus Novirhabdovirus, continues to be one of the most detrimental pathogens impacting salmonid aquaculture on a global scale. Notable for inducing high mortality rates among fry and fingerlings, IHNV represents a substantial threat to the economic stability of the aquaculture industry. This review offers an in-depth analysis of the contemporary advancements in IHNV vaccine development. Methods: We assess the efficacy and immunological mechanisms of traditional vaccine platforms, including inactivated and live-attenuated vaccines, while emphasizing the groundbreaking success of DNA vaccines, particularly those encoding the viral glycoprotein (G). Although nucleic acid-based therapies provide high levels of protection, they face logistical challenges related to delivery and regulatory obstacles associated with Genetically Modified Organisms (GMOs). Additionally, we examine emerging “next-generation” platforms, such as viral vector vaccines, subunit proteins produced in yeast or plant systems, and RNA-based technologies. We critically analyze technical bottlenecks, including the lack of efficient mucosal delivery systems and the limited understanding of long-term cellular memory in teleosts. Results: We propose future research directions that emphasize the development of multivalent formulations and the incorporation of molecular adjuvants to augment mucosal immunity. Conclusions: This synthesis seeks to integrate fundamental viral pathogenesis with applied immunology to develop a strategic framework for the sustainable, long-term management of IHNV in global salmonid populations.