Structural alteration of a BYDV-like translation element (BTE) that attenuates p35 expression in three mild Tobacco bushy top virus isolates

Deya Wang,Shanshan Liu,Xuefeng Yuan,Xiangdong Li,Guolu Wang,Kerong Shi,Chengming Yu

doi:10.1038/s41598-017-04598-5

Deya Wang, Shanshan Liu + Show 5 more

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https://doi.org/10.1038/s41598-017-04598-5

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Journal: Scientific Reports	Publication Date: Jun 23, 2017
Citations: 12	License type: open-access

Affiliation: Shandong Agricultural University

Abstract

To identify the molecular effects of Tobacco bushy top virus (TBTV) evolution on the degeneration of tobacco bushy top disease, three TBTV isolates with mild virulence were compared with wild-type TBTV to assess the translation of p35, which relies on a BYDV-like translation element (BTE) in a cap-independent manner. The in vitro expression of p35 in the mild isolates was only 20% to 40% of the expression observed in wt TBTV. Based on translation data from chimeric TBTV RNA, low-level p35 expression in the three mild isolates was associated with two regions: the 5′ terminal 500 nt region (RI) and the 3′ internal region (RV), which included the BTE. For the RV region, low level p35 expression was mainly associated with structural alterations of the BTE instead of specific sequence mutations within the BTE based on SHAPE structural probing and mutation analysis. Additionally, structural alteration of the TBTV BTE resulted from mutations outside of the BTE, implying structural complexity of the local region surrounding the BTE. This study is the first report on the structural alteration of the 3′ cap-independent translation element among different isolates of a given RNA virus, which is associated with variations in viral virulence.

Highlights

Undergo rapid evolution under natural selection with a higher mutation rate (10−3–10−5) due to error-prone replication in infected cells and organisms[18, 19]
Different 3′ CITEs have been identified from various RNA viruses, few studies have focused on the structural variations of these 3′ CITEs among different isolates of given RNA virus
Tobacco bushy top virus (TBTV), which is a member of the genus Umbravirus in the family Tombusviridae, and Tobacco vein distorting virus (TVDV), which is a member of the genus Polerovirus in the family Luteoviridae, were causal agents of tobacco bushy top disease in sub-Saharan Africa in the 1960s20 and in Asia, including China, in the 1990s21

Summary

Introduction

Undergo rapid evolution under natural selection with a higher mutation rate (10−3–10−5) due to error-prone replication in infected cells and organisms[18, 19]. During TBTV infection, the symptom could be associated with translation of the viral proteins, replication of the viral genome, virus movement and so on. The emphasis was focused on the relationship and mechanism between the differential expression of p35 and TBTV virulence in different isolates. CDNA clones of three TBTV isolates showing mild virulence in the field were constructed, and the cap-independent translation of p35 was analyzed in vitro. The p35 expression level of these mild isolates was only 20% to 40% of wild-type TBTV-Ch (TBTV China isolate in this study).

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