The present disclosure provides dual viruses capable of producing a primary virus and a secondary virus, and dual oncolytic viruses capable of producing a primary oncolytic virus and a secondary oncolytic virus.

Provided are an optimized CPY4V2 gene and an application thereof. The gene relates to a polynucleotide for coding a CYP4V2 protein, and comprises a nucleotide sequence having 90% or over 90% of identity with a nucleotide sequence as shown in SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9. Also provided is an expression vector comprising the gene. The expression vector can realize lasting and stable expression in retinal pigment epithelium of eyes, can effectively reduce the dosage and possible side effects of a gene therapy drug for treating BCD, and improves the therapeutic effect.

Provided are an optimized CPY4V2 gene and an application thereof. The gene relates to a polynucleotide for coding a CYP4V2 protein, and comprises a nucleotide sequence having 90% or over 90% of identity with a nucleotide sequence as shown in SEQ ID NO: 5, SEQ ID NO: 6, SEQ ID NO: 7, SEQ ID NO: 8 or SEQ ID NO: 9. Also provided is an expression vector comprising the gene. The expression vector can realize lasting and stable expression in retinal pigment epithelium of eyes, can effectively reduce the dosage and possible side effects of a gene therapy drug for treating BCD, and improves the therapeutic effect.