Evaluation of protective effect of infectious hematopoietic necrosis (IHN) oral DNA vaccine wrapped with 4 different delivery vectors against IHN virus (IHNV) infection in rainbow trout (Oncorhynchus mykiss).

Infectious hematopoietic necrosis (IHN) is a kind of viral disease with high pathogenicity and high mortality caused by infectious hematopoietic necrosis virus (IHNV), which had an adverse effect on farmed salmonids. Previously, the research group has developed IHN inactivated vaccines and DNA vaccines for injection with good protection effect and long protection period. In this study, IHN DNA vaccine was wrapped in poly (lactic-co-glycolic acid) (PLGA, 75:25), chitosan (CS), sodium alginate (SA) and MONTANIDE™ GR01 and fed to rainbow trout (Oncorhynchus mykiss) fry (10 ± 2 g), followed by intraperitoneal injection challenge experiment (1000TCID50, 100 μL per fish) to explore the protective effect of DNA vaccine with four different delivery vectors against IHNV infection. The results showed that compared with CS, SA and PLGA, MONTANIDE™ GR01 is more suitable as a delivery vector of IHN DNA vaccine. In addition, high-dose IHN DNA vaccine mixed with MONTANIDE™ GR01 feeding to rainbow trout fry can effectively inhibit the proliferation of IHNV virus, induce the body's early immune response and improve the relative survival rate. In this study, a delivery vector of IHN DNA oral vaccine for rainbow trout was initially screened, which provided a basis for the development of subsequent oral vaccines.