Functional analysis of apple stem pitting virus coat protein variants

Xiaofang Ma; Ni Hong; Peter Moffett; Yijun Zhou; Guoping Wang

doi:10.1186/s12985-019-1126-8

Functional analysis of apple stem pitting virus coat protein variants

Virol J. 2019 Feb 8;16(1):20. doi: 10.1186/s12985-019-1126-8.

Authors

Xiaofang Ma^{1

2

3

4}, Ni Hong^{1

2}, Peter Moffett³, Yijun Zhou⁴, Guoping Wang^{5

6}

Affiliations

¹ State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, 430070, People's Republic of China.
² Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, People's Republic of China.
³ Centre SÈVE, Département de Biologie, Université de Sherbrooke, 2500 Blvd. de l'Université, Sherbrooke, QC, J1K 2R1, Canada.
⁴ Jiangsu Academy of Agricultural Sciences, Key Lab of Food Quality and Safety of Jiangsu Province-State Key Laboratory Breeding Base, Institute of Plant Protection, Nanjing, 210014, China.
⁵ State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan, Hubei, 430070, People's Republic of China. gpwang@mail.hzau.edu.cn.
⁶ Key Laboratory of Plant Pathology of Hubei Province, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, Hubei, 430070, People's Republic of China. gpwang@mail.hzau.edu.cn.

Abstract

Background: Although the canonical function of viral coat protein (CP) is to encapsidate the viral genome, they have come to be recognized as multifunctional proteins, involved in almost every stage of the viral infection cycle. However, CP functions of Apple stem pitting virus (ASPV) has not been comprehensively documented. This study aimed to characterize the functions of ASPV CP and any functional diversification caused by sequence diversity of six ASPV CP variants and studied their biological, serological, pathogenic and viral suppressor of RNA silencing (VSR) functions.

Methods: Six ASPV CP variants that have previously been shown to belong to different subgroups were selected here to study their diversity functions. Agrobacterium mediated infiltration (Agroinfiltration) was used to express YFP-ASPV-CPs in Nicotiana. benthamiana and infect Nicotiana. occidental with PVX-ASPV-CPs in. Confocal microscopy was used to detect YFP-ASPV-CPs florescence. CPs expressed in Escherichia coli BL21 (DE3) were induced by IPTG.

Results: In this study, we showed that recombinant CPs expressed in Escherichia coli BL21 (DE3) had different levels of serological reactivity to three anti-ASPV antibodies used to detect ASPV. Furthermore, fusion CPs with YFP (YFP-CPs) expressed in N. benthamiana cells differed in their ability to form aggregates. We also showed that ASPV isolates that harbour these CPs induced different biological symptoms on its herbaceous host N. occidentalis. At the same time, we found that all six CPs when expressed in PVX vector showed similar VSR activity and produced similar symptoms in N. occidentalis, despite their differences in amino acids.

Conclusions: Different ASPV isolates induced different symptoms in N. occidentalis, however, ASPV CP variants expressed in PVX vector showed the same symptoms in N. occidentalis plants. Also, we showed that ASPV CP variants has the same level of VSR activity, but they have different abilities to aggregate in N. benthamiana.

Keywords: Aggregate; Apple stem pitting virus; CP variants; Coat protein; RNA silencing suppressor.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Antibodies, Viral
Capsid Proteins / genetics*
Escherichia coli / genetics
Flexiviridae / genetics*
Flexiviridae / metabolism
Genome, Viral
Nicotiana / virology
RNA Interference
RNA, Viral / genetics
Recombinant Proteins / genetics
Viral Proteins / genetics*
Viral Proteins / metabolism

Substances

Antibodies, Viral
Capsid Proteins
RNA, Viral
Recombinant Proteins
Viral Proteins

Supplementary concepts

Apple stem pitting virus