The present disclosure provides methods of modulating immunodeficiency virus transcription, involving modulating enzymatic activity and/or levels of a lysine-specific demethylase-1 (LSD1) polypeptide and/or LSD1-mediated demethylation of methylated Tat. The present disclosure also provides method of identifying agents that modulate LSD1-mediated demethylation of a human immunodeficiency virus (HIV) Tat polypeptide.