The novel picornavirus Equine rhinitis B virus contains a strong type II internal ribosomal entry site which functions similarly to that of Encephalomyocarditis virus
- Author(s)
- Hinton, TM; Crabb, BS;
- Journal Title
- JOURNAL OF GENERAL VIROLOGY
- Publication Type
- Journal Article
- Abstract
- Equine rhinitis B virus (ERBV) has recently been classified as an Erbovirus, a new genus in the Picornaviridae family. ERBV is distantly related to members of the Cardiovirus and Aphthovirus genera which utilize a type II internal ribosome entry sequence (IRES) to initiate translation. We show that ERBV also possesses the core stem-loop structures (H-L) of a type II IRES. The function of the ERBV IRES was characterized using bicistronic plasmids that were analysed both by transfection into BHK-21 cells and by in vitro transcription and translation in rabbit reticulocyte lysates. In both systems, a region encompassed by nucleotides (nt) 189-920 downstream of the poly(C) tract was required for maximal translation. This sequence includes stem-loops H-L as well as four additional upstream stem-loops. Nt 904 corresponds to the second of three in-frame AUG codons located immediately downstream of the polypyrimidine tract (nucleotides 869-880). Site-directed mutagenesis demonstrated that AUG2 is the major initiation codon despite the appropriate positioning of AUG1 16 nt downstream of the polypyrimidine tract. In direct IRES competition experiments, the ERBV IRES was able to compete strongly for translation factors with the IRES of Encephalomyocarditis virus (EMCV). This was true when the assays were performed in vitro (with the IRESs competing either in cis or trans) and in vivo (with the IRESs competing in cis). A comparative analysis of the strength of several IRESs revealed that the ERBV IRES, like that of the EMCV, is a powerful inducer of translation and may have similar potential for use in mammalian expression systems.
- Publisher
- SOC GENERAL MICROBIOLOGY
- Keywords
- MOUTH-DISEASE VIRUS; MURINE ENCEPHALOMYELITIS VIRUS; ALTERNATIVE TRANSLATION INITIATION; CAP-INDEPENDENT TRANSLATION; 5' NONTRANSLATED REGION; STRUCTURAL ELEMENTS; SECONDARY STRUCTURE; 5'-UNTRANSLATED REGION; RNA TRANSLATION; SEQUENCE
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Creation Date: 2001-09-01 12:00:00