Enhanced IRES activity by the 3′UTR element determines the virulence of FMDV isolates

Abstract

A reverse genetics approach was used to identify viral genetic determinants of the differential virulence displayed by two field foot-and-mouth disease virus (FMDV) strains (A/Arg/00 and A/Arg/01) isolated in Argentina during the 2000-2001 epidemics. A molecular clone of A/Arg/01 strain and viral chimeras containing the S-fragment or the internal ribosome entry site (IRES) of A/Arg/00 in the A/Arg/01 backbone were constructed and characterized. The IRES appeared as a determining factor of the lower level of A/Arg/00 replication in cell culture. High-throughput RNA probing revealed structural differences between both IRESs. Translation experiments using either synthetic viral RNAs (in vitro) or bicistronic plasmids (in vivo) showed that these IRESs' activities differ when the viral 3' untranslated region (UTR) is present, suggesting that their function is differentially modulated by this region. This work provides experimental evidence supporting the role of the IRES-3'UTR modulation in determining the level of FMDV replication in field strains.

In-cell SHAPE uncovers dynamic interactions between the untranslated regions of the foot-and-mouth disease virus RNA

“…Previous data reported that the 3΄UTR stimulates IRES activity both in the viral RNA (37) or when placed at the 3΄ position of a reporter gene (27). In addition, direct RNA–RNA interactions between these distant regions of the viral genome have been shown in vitro (1).…”

“…The 3΄UTR is essential for aphthovirus replication (34) although there are controversial results in other picornaviruses (35,36). In the case of the foot-and-mouth disease virus (FMDV) IRES, internal initiation of translation was stimulated by the 3΄UTR (27,37), regardless of the coexpression of the L protease. Therefore, IRES activity was stimulated both in the presence or absence of proteolyzed eIF4G and PABP.…”

Picornavirus IRES elements: RNA structure and host protein interactions

“…Various studies support an active role for interactions between the 5 and 3 ends of the viral RNA in controlling picornavirus gene expression. For instance, PV IRES activity in neuronal cells was stimulated by the viral 3 UTR (Dobrikova et al, 2003), and the FMDV IRES was stimulated by its own 3 UTR (Garcia-Nunez et al, 2014;Lopez de Quinto et al, 2002), irrespectively of the presence of polyA tail and the coexpression of the L protease.…”

Duck hepatitis A virus serotype 1 minigenome: a model for studying the viral 3′UTR effect on viral translation

“…Previous studies have shown that the 5 0 UTR of the viral genome harbored the hepatitis C virus like (HCV-like) IRES element [4,19]. The IRES element is responsible for the internal initiation of translation of viral RNA [20]. Thus, the plasmid pSK-D5 0 UTR was used as a negative control corresponding to a reduction in Fluc activity.…”