A mutational anlaysis of the N-terminal protease of bovine viral diarrhea virus |
Seung-ki Chon |
Department of Veterinary and Biomedical Sciences, University of Nebraska-Lincoln |
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Abstract |
The uncaped genomic RNA of bovine viral diarrhea virus (BVDV) initiates translation by recruitment of eukaryotic translation initiation factors at the internal ribosome entry site (IRES). N-terminal protease ($N^{pro}$) is the first translation product of the open reading frame (ORF). By using the vaccinia virus SP6 RNA polymerase transient expression system, we showed previously that deletion of $N^{pro}$ region reduced translation by 21%. To better understand the biological significance of $N^{pro}$ for translation, we carried out a mutational analysis of the $N^{pro}$ region of BVDV cloned in the intercistronic region of a bicistronic reporter plasmid. We constructed a bicistronic expression vector in which the entire 5 UTR and the mutated $N^{pro}$ region (${Delta}386-901$, ${Delta}415-901$ and ${Delta}657-901$) was cloned between two reporter genes, chloramphenicol acetyltransferase (CAT) and luciferase (LUC). In vivo translation analyses showed that $N^{pro}$ region was dispensible for efficient translation. The results indicate that the $N^{pro}$ region is not essential for BVDV RNA translation and the 3' boundary of BVDV IRES is expanded into $N^{pro}$ region, suggesting that $N^{pro}$ may not play a major role in BVDV replication. |
Key Words:
Bovine viral diarrhea virus, internal ribosome entry segment, N-terminal protease |
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