Immune response of freshwater fish, guppy, Poicelia reticulata and gouramy, Trichogaster trichopterus to recombinant coat protein of Epinephelus tauvina nervous necrosis virus

Immune response of guppy, Poicelia reticulata and gouramy, Trichogaster tricopterus towards recombinant coat protein of nervous necrosis virus was evaluated by immersion and injection immunization, respectively, and the response was compared with that against the formalin-inactivated Epinephelus tauvina nervous necrosis virus (ETNNV). In vitro neutralization of ETNNV and guppy nervous necrosis virus (GNNV) was performed to measure the neutralizing antibody response. In vitro neutralization using the whole-body extract of immersion immunized guppy and the antisera from injection immunized gouramy showed that the formalin-inactivated ETNNV, and its recombinant coat protein induce neutralizing antibody response in fish. In addition, the rabbit polyclonal antisera raised against the recombinant coat protein of ETNNV also neutralized the GNNV and ETNNV in vitro showing the importance of recombinant coat protein as a candidate vaccine against viral nervous necrosis and its suitability for immersion delivery.