Poliovirus tropism and attenuation are determined after internal ribosome entry
Steven E. Kauder, Vincent R. Racaniello
Steven E. Kauder, Vincent R. Racaniello
Published June 15, 2004
Citation Information: J Clin Invest. 2004;113(12):1743-1753. https://doi.org/10.1172/JCI21323.
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Categories: Article Virology

Poliovirus tropism and attenuation are determined after internal ribosome entry

Abstract

Poliovirus replication is limited to a few organs, including the brain and spinal cord. This restricted tropism may be a consequence of organ-specific differences in translation initiation by the poliovirus internal ribosome entry site (IRES). A C-to-U mutation at base 472 in the IRES of the Sabin type 3 poliovirus vaccine strain, known to attenuate neurovirulence, may further restrict tropism by eliminating viral replication in the CNS. To determine the relationship between IRES-mediated translation and poliovirus tropism, recombinant human adenoviruses were used to express bicistronic mRNAs in murine organs. The IRESs of poliovirus, the cardiotropic coxsackievirus B3 (CVB3), and the hepatotropic hepatitis C virus (HCV) mediate translation in many organs, including those that do not support viral replication. A translation defect associated with the Sabin type 3 IRES was observed in all organs examined. Poliovirus type 1 and recombinant polioviruses dependent on the IRES of CVB3 or HCV replicate in the CNS of mice and cause paralysis. Although the type 3 Sabin strain is an effective vaccine, polioviruses with a U at base 472 of the IRES cause paralysis in newborn mice. Tropism of wild-type and vaccine strains of poliovirus is therefore determined after internal ribosome entry.

Authors

Steven E. Kauder, Vincent R. Racaniello

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Figure 1

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IRES-mediated translation in A549 cells infected with recombinant adenov...
IRES-mediated translation in A549 cells infected with recombinant adenoviruses. (A) Schematic of bicistronic reporter DNA. The arrow indicates the transcription-initiation site of the murine cytomegalovirus immediate early promoter. Firefly luciferase and Renilla luciferase have independent translation initiation and termination codons. SV40 An, simian virus 40 polyadenylation signal. (B) IRES activity in cells infected with adenovirus encoding bicistronic mRNA. The x axis indicates IRES encoded in the recombinant adenovirus. PV 5′NC-X472, poliovirus IRES with XhoI linker substitution at nucleotide 472; HCV Ø28_69, HCV IRES with deletion of nucleotides 28_69. (C) Northern blot hybridization of A549 cells. Cells were infected with recombinant adenoviruses indicated at the top. RNA size markers are given at left. Lane 1, monocistronic firefly luciferase; lane 2, monocistronic Renilla luciferase; lane 3, bicistronic mRNA, no IRES; lane 4, bicistronic mRNA with P3/119/70 IRES; lane 5, bicistronic mRNA with P3/Sabin IRES; lane 6, bicistronic mRNA with HCV IRES; lane 7, bicistronic mRNA with HCV IRES lacking nucleotides 28_69. First two lanes are from the same gel as lanes 3_7 but were exposed for a longer period of time. (D) Luciferase expression in adenovirus-infected cells. Upper panel: Firefly luciferase (white bars) and Renilla luciferase expression (black bars). Luciferase was normalized to the P3/119/70 IRES value for each reporter protein, and also to the quantity of bicistronic mRNA determined by Northern blot hybridization. Lower panels: Representative Northern blot hybridizations of RNA from the same infected cells. IRES encoded by bicistronic mRNA is indicated at the bottom. Data points in B and D, the results of separate experiments, are the mean of three infections, and error bars indicate SD.