A nucleic acid comprising a transcription regulation sequence whose transcription is induced by a trans-acting factor of a human immunodeficiency virus and a gene encoding a polypeptide having an endoribonuclease activity specific to single-stranded RNA, wherein the gene is located in such a position that the expression of the gene can be regulated by the transcription regulation sequence; a method for production of a cell showing an inhibited replication of a human immunodeficiency virus therein, the method comprising the step of introducing the nucleic acid into a cell; and a method for treatment or prevention of a human immunodeficiency virus infection.