Pestivirus translation initiation occurs by internal ribosome entry

Abstract

The role of the 385 nucleotide 5' noncoding region (NCR) in the translation of the pestivirus genome was investigated. In vitro translation of an RNA transcript containing the 5' NCR of the bovine viral diarrhea virus (BVDV) genome followed by the coding sequence of the first gene product (p20) of the BVDV large open reading frame resulted in the synthesis of a 20-kDa polypeptide. Results from hybrid-arrest translation studies identified a region involving a predicted RNA stem-loop structure spanning nucleotides 154-261 within the 5' NCR that was important for p20 synthesis. An additional inhibitory oligonucleotide was complementary to the sequence at the base of this stem-loop and encompassed the initiating AUG at nucleotide 386. Antisense oligonucleotides both upstream and downstream of those that were inhibitory had no effect on p20 translation. RNA from a dicistronic expression vector in which the BVDV 5' NCR was inserted between two reporter genes, CAT and LUC, showed strong expression of the second (LUC) cistron upon in vitro translation. This expression was dramatically reduced in an analogous construct in which nucleotides 173-236 of the 5' NCR were deleted. Similar results were obtained when RNA from these same vectors was evaluated for expression after transfection into BHK cells. These results suggest that the BVDV 5' NCR contains an internal ribosome entry site for translation initiation. This translational mechanism is similar to that shown for hepatitis C virus, further demonstrating the close relationship between viruses of these two genera within the family Flaviviridae.

Genetic Analysis of a Poliovirus/Hepatitis C Virus (HCV) Chimera: Interaction between the Poliovirus Cloverleaf and a Sequence in the HCV 5′ Nontranslated Region Results in a Replication Phenotype

“…Similar genetic elements have also been discovered in genomes of Hepatitis C virus (HCV) (24), a Hepacivirus, and Bovine viral diarrhea virus (21), a Pestivirus, of the Flaviviridae family. IRESs are located in the 5Ј-terminal segment of the genomes, where they control initiation of polyprotein synthesis.…”

The RU5 (‘R’) region from human leukaemia viruses (HTLV‐1) contains an internal ribosome entry site (IRES)‐like sequence

“…RNA sequences having IRES properties has been found in number of viruses including most, if not all, the members of the picornavirus family [8], in hepatitis C [9], murine hepatitis virus [10], pestivirus [11], Moloney mouse leukaemia virus [12] and Friend mouse leukaemia virus [13]. These structures have a more or less similar mechanism of action [14,15].…”

A prokaryotic-like mode of cytoplasmic eukaryotic ribosome binding to the initiation codon during internal translation initation of hepatitis C and classical swine fever virus RNAs

“…Hepatitis C virus (HCV) and pestiviruses such as classical swine fever virus (CSFV) and bovine viral diarrhea virus constitute another IRES group (Brown et al 1992;Tsukiyama-Kohara et al 1992;Poole et al 1995;Rijnbrand et al 1997). Ribosomal entry also occurs at or immediately upstream of the initiation codon on HCV-like IRESs and initiation probably also does not involve scanning (Reynolds et al 1995(Reynolds et al , 1996Rijnbrand et al 1995Rijnbrand et al , 1996Rijnbrand et al , 1997Wang et al 1995;Honda et al 1996;Lu and Wimmer 1996).…”