Maternal Immunity and Immune Improvement of Koi Cyprinus rubrofuscus Larvae after DNA Vaccine against Hoi Herpesvirus

Vaccination is an efficient step in preventing disease caused by koi herpesvirus in koi fish (Cyprinus rubrofuscus). This study aimed to investigates the impact of maternal broodstock vaccination with ORF81 DNA vaccine on the transmission of maternal immunity to offspring against KHV. The ORF81 DNA vaccine has been shown to increase RPS, but its effect on maternal immunity in koi offspring after vaccination has not been evaluated. The study examined koi broodstocks vaccinated with the ORF81 DNA vaccine 45 and 60 days before spawning (45V and 60V) at a dose of 12.5 μg/100 g. Immunological parameters were assessed in broodstock, eggs, and larvae. Immune gene expression was also analyzed using the qPCR method. The results showed that lysozyme activity and antibody levels in eggs from vaccinated mothers were higher, though not significantly different. Meanwhile, lysozyme activity and antibody levels in mothers were significantly higher (p<0.05) compared to controls. Immunoglobulin-M gene (IgM) and recombination-activating gene 1 (RAG1), were significantly induced. The relative survival percentage increased significantly in larvae produced from broodstocks with 60V. These findings indicate that broodstocks treated with the ORF81 DNA vaccine can enhance the immune response of their offspring.