The invention provides an ORF074 (
Open Reading Frame 074)
gene deleted strain of an infectious
spleen and
kidney necrosis virus as well as a preparation method and application thereof. The ORF074 genedeleted strain is an attenuated viral strain prepared after the ORF074
gene is deleted from an infectious
spleen and
kidney necrosis viral strain. The invention also provides a selection marker carrying ORF074
gene deleted strain of the infectious
spleen and
kidney necrosis virus as well as a preparation method and application thereof. The selection marker carrying ORF074 gene deleted strain is an attenuated viral strain prepared after the ORF074 gene is deleted from the infectious spleen and
kidney necrosis virus and further a selection
marker gene is inserted into a gene deleted position through
homologous recombination. The ORF074 gene deleted strain of the infectious spleen and
kidney necrosis virus, which is provided by the invention, is an ORF074 knocked-out recombinant
gene engineering vaccine, is lower in
virulence, and is used for greatly reducing the morbidity and
lethality of an immunized fish; the obvious immunization effect can be achieved by adopting immersion immunization; the injection is not needed, and the application value is extremely high.