The implantation rate of the stem cell of gene modification is improved by adjusting and internal selection strategy for the potent short hairpin RNA (shRNA734) of mankinds hypoxanthine guanine phosphoribosyltransferase (HPRT), the adjusting and internal selection strategy assign the resistance to useful clinically guanine analog antimetabolite 6TG, to realize effective positive selection of gene modification stem cell. The purposes of polynucleotides comprising shRNA734 includes the method for knocking out the HPRT in cell, method for assigning guanine analog antimetabolite resistance in cell, method for generating selectable genetically modified cell, for the selection method of the cell of target gene genetic modification from multiple cells, for the method for the removal cell of target gene genetic modification from multiple cells, and the method for the subject for treating infected by HIV.
