Establishment of Minigenomes for Infectious Bursal Disease Virus

Minigenomes (MG) have greatly advanced the research on the viral life cycle, including viral replication and transcription, virus-host interactions, and the discovery of antivirals against RNA viruses. However, a MG for infectious bursal disease virus (IBDV) has not been well established. Here, we describe the development of IBDV MG wherein the entire coding sequences of viral genomic segments A and B were substituted by Renilla luciferase (Rluc) or enhanced green fluorescent protein (EGFP) reporter genes. Under the control of RNA polymerase I promoter, the translation of IBDV MG is controlled by viral proteins VP1 and VP3. Interestingly, the IBDV B MG shows higher activity than IBDV A MG. Moreover, the sense IBDV B MG was expressed into a higher level than the antisense one. In agreement with our previous findings, translation of IBDV B MG controlled by VP1 and VP3 is independent of the cellular translation machinery components eukaryotic initiation factor (eIF)4E and eIF4G but the intact VP1 polymerase activity, the VP3 dsRNA-binding activity, and the interaction between VP1 and VP3 are indispensable for both sense and antisense IBDV B MG activity. In addition, Ribavirin, which inhibits IBDV replication, shows an inhibition effect on IBDV B MG activity in a dose-dependent manner. Collectively, the IBDV MG established in this study provides a powerful tool to investigate IBDV intracellular replication and transcription, virus-host interaction, and facilitates high throughput screening for the identification of IBDV antivirals.