Analysis of the packaged IBV particles revealed that leader sequence switching occurs between the D-RNA and the IBV helper viruses, which was similarly observed in bovine coronavirus. In addition, it was found that the TAS of the IBV D-RNA contained a consensus sequence that can accept the switched leader sequence and can also be involved in the expression of mRNA from D-RNA.
Investigation into the packaged IBV particles revealed an exchange of leader sequences between the D-RNA and helper viruses, similar to what was observed in bovine coronavirus. Furthermore, it was found that the TAS of the IBV D-RNA contains a common sequence capable of accepting the exchanged leader sequence and contributing to mRNA production from D-RNA.