Expression cassette for expressing gene comprising overlapping open reading frames in insect cell and application thereof

An expression cassette for expressing a gene comprising overlapping open reading frames in an insect cell, comprising from 5′ to 3′ and operably linked:

• a promoter capable of driving transcription in the insect cell;
• an artificially constructed sequence comprising a 5′ part of a first open reading frame;
• a 3′ part of the first open reading frame comprising at least one additional open reading frame;
• wherein the artificially constructed sequence comprises a native or engineered intron with splicing activity in the insect cell, the intron comprises a translation start codon ATG of the first open reading frame or the intron is located between any two adjacent nucleotides in ATG, so that the 5′ part of the first open reading frame lacks a translation start codon, and the intron does not comprise a promoter capable of driving transcription in the insect cell;
• the at least one additional open reading frame comprises at least one additional translation start codon;
• the expression cassette can only transcribe a precursor mRNA in the insect cell, and -during a post-transcriptional processing process, a translation start codon AUG in the artificially constructed sequence is retained or deleted or a translation start codon AUG is formed in the artificially constructed sequence only through an alternative splicing function of the intron, thereby implementing translation and expression of different overlapping open reading frames.