HIV Tat protein requirements for transactivation and repression of transcription are separable

The Tat protein may have important and distinct effects on HIV replication and the immune response. Researchers found that the Tat protein, generated by the virus which causes HIV infection, promotes viral genetic transcription and, thus, virus replication. Another region of the protein may repress genetic transcription of the major histocompatibility complex, which may impair the ability of white blood cells to attack HIV infected cells.