Abstract
Anguillid herpesvirus (AngHV) is the causative agent of ‘mucus sloughing and hemorrhagic septicemia disease’ in eels. Egg yolk immunoglobulin (IgY) has been reported to serve as oral administration of antibodies against bacterial and viral pathogens. In this study, an inactivated vaccine of AngHV was developed to immunise the laying hens, thereby facilitating the production of anti‐AngHV IgY. The yolks were subsequently collected and processed into a dry yolk powder, and IgY was extracted from the yolk powder. The anti‐AngHV efficacy of the IgY was assessed through both in vitro and in vivo assays. In vitro analyses showed that the purified IgY was capable of neutralizing AngHV in an antibody concentration‐dependent manner. In the in vivo experiment, the incorporation of 6‰ yolk powder into the diet of eels exhibited no negative impact on growth performance, intestinal tissue morphology, intestinal microbiota, and metabolic profiles. However, the incidence of morbidity in AngHV‐infected eels decreased from 100% to 71%, while mortality rates declined from 57.14% to 28.57%. Additionally, the concentration of AngHV in the skin mucus was significantly reduced. This study provides the evidence that the anti‐AngHV IgY can effectively confer protection to eels against AngHV infection, thereby establishing a foundation for the development of anti‐AngHV therapy products using the yolk powder.