Infectious hematopoietic necrosis virus (IHNV) in fish and its consequences for fish farming: A comprehensive review

Viral diseases are a major concern in finfish aquaculture, leading to severe health problems. Infectious hematopoietic necrosis (IHN) is a highly transmissible systemic viral disease that primarily affects salmonids, causing significant mortality and economic losses to the salmonid farming industry. This review covers all major aspects of the virus, including its morphology and structure, replication cycle, geographical distribution, transmission, susceptibility and ultrastructural analysis. It also provides a comprehensive phylogenetic analysis of IHNV strains, specifically focusing on the G, N, M and NV genes, underscoring the importance of developing vaccines that are genetically aligned with circulating viral variants to improve immunization efficacy. In addition, this review addresses disease progression, prevalence, immunological responses, host range, clinical and histological appearance, diagnostic methods, control and management strategies, including current vaccine options. Molecular mechanisms of IHNV pathogenesis are discussed with particular emphasis on glycoprotein G as a key target for neutralizing antibodies and vaccine development. A detailed understanding of IHN and its prevention is essential for maintaining healthy aquaculture stocks, supporting sustainable production and meeting global demand for fish and fish-derived products.