passages.id: split_4_test_2667_passage
passages.type: progene_text
passages.text: Human immunodeficiency virus , type 1 ( HIV - 1 ) replication requires the interaction of Tat protein with the human cyclinT1 ( hCyclinT1 ) subunit of the positive transcription elongation factor ( P - TEFb ) complex , which then cooperatively binds to transactivation response element ( TAR ) RNA to transactivate HIV transcription .