Construction and application of eukaryotic expression vector carrying double-screening genes

The invention specifically relates to a eukaryotic expression vector pAAV2neo-dhfr carrying dhfr and neo genes. The expression vector is mainly composed of ITR of AAV2, neo gene expression cassette, dhfr gene expression cassette, and an exogenous gene expression cassette. The exogenous gene expression cassette comprises a multiple cloning sites MCS used for expressing exogenous gene insertion. When in use, the exogenous gene is inserted between the multiple cloning sites MCS, such that an exogenous gene expression vector is obtained; expressing cell transfection is carried out, and an exogenous gene stable high-expression cell line is selected by using various strategies. The vector carries the ITR sequence of AAV2, such that exogenous gene stable-expression cell line production is facilitated. The vector comprises two screening genes suitable for various expression cells, and stable high-expression cell line screening process is shortened. With the vector, various exogenous genes can be highly efficiently ex