Internal initiation and frameshifting in infectious bursal disease virus sequence expressed in Escherichia coli.

As part of our efforts to produce native molecules of the host protective antigen (VP2) of infectious bursal disease virus (IBDV) in microorganisms, we have restored nucleotide sequences encoding the VP2 N-terminus which were not present in the original clone. In addition to this process, we produced constructs that contained +5, +4, -1, and -2 frameshifts that still allowed expression of the IBDV polyprotein, VP2 and VP3. The size of translation products and examination of the nucleotide sequence lead us to speculate that both +1 frameshifting and internal initiation events lead to the synthesis of IBDV proteins in Escherichia coli.