title: The pseudorabies virus vhs protein cleaves RNA containing an IRES sequence.
abstract: The virion host shutoff protein (vhs), encoded by the gene UL41, has RNase activity and is the key regulator of the early host shutoff response induced by type 1 herpes simplex virus. Despite low amino acid similarity, the vhs protein of the swine herpesvirus, pseudorabies virus (PrV), also exhibits RNase activity. However, the mechanism underlying the action of vhs remains undefined. Here, we report that the RNA degradation profile of PrV vhs is similar, but not identical, to that of type 1 herpes simplex virus vhs. Notably, the presence of a cap structure enhances both the degradation rate and the preferential targeting of the vhs protein towards the 3'-end of the encephalomyocarditis virus internal ribosome entry site (IRES). Furthermore, type 1 herpes simplex virus vhs produces a simple degradation pattern, but PrV vhs gives rise to multiple intermediates. The results of northern blotting using probes recognizing various regions of the RNA substrate found that PrV vhs also cleaves downstream of the IRES region and this vhs protein overall shows 5' to 3' RNase activity. Moreover, addition of the translation initiation factors eIF4H and eIF4B significantly increased the RNase activity of recombinant PrV vhs against capped RNA. Nonetheless, these proteins did not fully reconstitute the IRES-directed targeting pattern observed for vhs translated in a rabbit reticular lysate system. The interaction between PrV vhs and eIF4H/eIF4B implies that the translation initiation machinery within the cell is able to stimulate the nuclease activity of PrV vhs. However, this process remains inefficient in terms of the IRES-targeting pattern.
authors.affiliation: Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Ya-Fen
authors.initials: YF
authors.lastname: Liu
authors.affiliation: Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Pei-Yun
authors.initials: PY
authors.lastname: Tsai
authors.affiliation: Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Songkhla
authors.initials: S
authors.lastname: Chulakasian
authors.affiliation: Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.|Department of Beauty Science, MeiHo University, Neipu, Taiwan.
authors.forename: Fong-Yuan
authors.initials: FY
authors.lastname: Lin
authors.affiliation: Graduate Institute of Microbiology and Public Health, College of Veterinary Medicine, National Chung Hsing University, Taichung, Taiwan.
authors.forename: Wei-Li
authors.initials: WL
authors.lastname: Hsu
mesh_terms: D000818:Animals; D001483:Base Sequence; D039642:Eukaryotic Initiation Factors / Q000378:metabolism; D017353:Gene Deletion; D057809:HEK293 Cells; D011558:Herpesvirus 1, Suid / Q000737:chemistry*; D006801:Humans; D000067556:Internal Ribosome Entry Sites; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D012367:RNA, Viral / Q000737:chemistry*; D011817:Rabbits; D011994:Recombinant Proteins / Q000737:chemistry; D012260:Ribonucleases / Q000378:metabolism*; D014158:Transcription, Genetic; D014764:Viral Proteins / Q000378:metabolism*; D014771:Virion / Q000737:chemistry*
chemical_list: C111495:EIF4H protein, human; D039642:Eukaryotic Initiation Factors; D000067556:Internal Ribosome Entry Sites; D012367:RNA, Viral; D011994:Recombinant Proteins; D014764:Viral Proteins; C031799:eIF-4B; C070722:virion host shutoff protein, Simplexvirus; D012260:Ribonucleases
keywords: RNase; herpes simplex virus; internal ribosome entry site; pseudorabies virus; virion host shutoff protein