Circularization of retroviral genomic RNA and the control of RNA translation, packaging and reverse transcription.

Translation, packaging and reverse transcription of the genomic RNA of retroviruses appear to be regulated by short and long range RNA-RNA interactions which take place within the 5'-600 nt and between the 5' and 3' untranslated sequences. The 5' (R and U5) and 3' (Dr and U3) domains of the genomic RNA together with the nucleic acid binding protein (NBP) would control the balance between the open state of the viral genomic RNA, correlated with an efficient RNA translation and the closed state, with the circular viral RNA efficiently packaged into virions. Retroviral NBP might well drive the packaging of the viral RNA as well as improve reverse transcription of the circular virion RNA.