National Institute of Animal Health (NIAH)

Topics in Animal Health Research 2003

10. Unique characteristics of a picornavirus internal ribosome entry site from the porcine teschovirus-1 talfan

  The teschoviruses constitute a recently defined picornavirus genus. Most of the genome sequence of the porcine teschovirus-1 (PTV) Talfan, a causal agent of porcine enterovirus encephalitis, and several other strains is known. We now demonstrate that just 280 nt of the porcine teschovirus type 1 Talfan (PTV-1) 5' untranslated region contains an internal ribosome entry site (IRES) that functions efficiently in vitro and within mammalian cells. In toeprinting assays, assembly of 48S preinitiation complexes from purified components on the PTV-1 IRES was achieved with just 40S ribosomal subunits plus eIF2 and Met-tRNA (i) (Met). Indeed, a binary complex between 40S subunits and the PTV-1 IRES is formed. Thus, the PTV-1 IRES has properties that are entirely different from other picornavirus IRES elements but highly reminiscent of the hepatitis C virus (HCV) IRES. Comparison between the PTV-1 IRES and HCV IRES elements revealed islands of high sequence identity that occur in regions critical for the interactions of the HCV IRES with the 40S ribosomal subunit and eIF3. Thus, there is significant functional and structural similarity between the IRES elements from the picornavirus PTV-1 and HCV, a flavivirus.
(Diagnosis Section, Department of Exotic Diseases   TEL +81-42-321-1441)

References:

  • Kaku et al. (2002) J. Virol. 76:11721-11728.
  • Pisarev et al. (2004) J. Virol. 78:4487-4497.

 

Centers・Institutes