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Influence of the 5' untranslated region internal ribosomal entry site and the Npro coding region on translational efficiency of bovine viral diarrhea virus genotype 2 isolates varying in virulence
Bovine viral diarrhea virus genotype 2 (BVDV2) isolates have a wide range of virulence. The central hypothesis for this research was that translational efficiencies of BVDV2 isolates are influenced by the structure of the 5′ untranslated region (UTR) internal ribosomal entry site (IRES) and the Npro coding region, which may influence BVDV virulence. Translational efficiencies of eight BVDV2 isolates were evaluated using bicistronic reporter assays. High virulence isolates had greater IRES-mediated translational efficiencies in bovine lymphocytes (BL-3 cells) than did low virulence isolates, consistent with the lymphotropism and severity of disease induced by high virulence isolates. Low virulence isolates translated with greater efficiency than high virulence isolates in rabbit reticulocyte lysates, African green monkey kidney (CV-1) and bovine turbinate (BT) cells. Mutagenesis of conserved bases at positions 219 and 278 within the IRES affected translational efficiencies, demonstrating that minor differences in primary/secondary structures and in host cell lines influence translational efficiency. In BT and BL-3 cells, the Npro coding region either had no influence or caused a significant decrease in IRES-mediated translational efficiency, with the exception of BVDV 890, where Npro increased IRES-mediated translational efficiency in BL-3 cells. Mutagenesis of IRES base 219 and/or 278 ameliorated suppression of the translational efficiency modulated by the Npro coding region. Results suggest interactions between the Npro coding region and nucleotides within and external to the IRES element influence translational efficiency. IRES element mutagenesis or addition of the Npro coding region to the 5′ UTR enhanced the characteristic low translational efficiency of the high virulent isolate 890, while decreasing the translational efficiency of low virulent isolates, such as 7937. These results underscore the complex interplay of cellular factors influencing IRES-mediated translation. These constructs will be useful in continued studies using an infectious full-length BVDV2 clone to characterize the interplay of the IRES and the Npro coding region of BVDV2 on virulence. ^
Biology, Molecular|Agriculture, Animal Pathology|Biology, Veterinary Science
Topliff, Christina Lynn, "Influence of the 5' untranslated region internal ribosomal entry site and the Npro coding region on translational efficiency of bovine viral diarrhea virus genotype 2 isolates varying in virulence" (2004). ETD collection for University of Nebraska - Lincoln. AAI3152621.