TAT and infection: Successful infection and production of new infectious HIV particles requires the balanced expression of seven viral proteins (Rev, Tat, Nef, Vif, Vpr, Vpu and Env) that are produced by splicing of the HIV-1 primary 9 kilobases (kb) transcript; among these, the Tat and Rev factors are essential for viral gene expression at the transcriptional and posttranscriptional levels in infected cells18,19.