Interaction of Structural Glycoprotein E2 of Classical Swine Fever Virus with Protein Phosphatase 1 Catalytic Subunit Beta (PPP1CB).

Elizabeth Vuono,Douglas Gladue,Manuel Borca,Ryan Baker-Branstetter,Elizabeth Ramirez-Medina,Lauren Holinka

doi:10.3390/v11040307

Elizabeth Vuono, Douglas Gladue + Show 4 more

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https://doi.org/10.3390/v11040307

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Abstract

Classical swine fever virus (CSFV) E2 protein, the major virus structural glycoprotein, is an essential component of the viral envelope. E2 is involved in virus absorption, induction of a protective immune response and is critical for virulence in swine. Using the yeast two-hybrid system, we identified protein phosphatase 1 catalytic subunit beta (PPP1CB), which is part of the Protein Phosphatase 1 (PP1) complex, as a specific binding host partner for E2. We further confirmed the occurrence of this interaction in CSFV-infected swine cells by using two independent methodologies: Co-immunoprecipitation and Proximity Ligation Assay. In addition, we demonstrated that pharmacological activation of the PP1 pathway has a negative effect on CSFV replication while inhibition of the PP1 pathway or knockdown of PPP1CB by siRNA had no observed effect. Overall, our data suggests that the CSFV E2 and PPP1CB protein interact in infected cells, and that activation of the PP1 pathway decreases virus replication.

Highlights

Classical Swine Fever (CSF) is a highly contagious disease of swine that is endemic in most ofAsia, Central and South America, and parts of Europe and Africa
We identified the protein phosphatase 1 catalytic subunit beta (PPP1CB)-E2 interaction by yeast two-hybrid and further confirmed that this protein–protein interaction occurs during Classical swine fever virus (CSFV) infection in swine cells by co-immunoprecipitation assays (CIPA) and by a proximity ligation assay (PLA)
We identified in the amino acid sequence of CSFV E2 protein a Phosphatase 1 (PP1) recognition motif and several predicted phosphorylation sites, suggesting that E2 is phosphorylated by PP1

Summary

Introduction

Classical Swine Fever (CSF) is a highly contagious disease of swine that is endemic in most ofAsia, Central and South America, and parts of Europe and Africa. Classical Swine Fever (CSF) is a highly contagious disease of swine that is endemic in most of. The etiological agent of this disease, Classical Swine Fever Virus (CSFV), is a small, enveloped virus possessing a positive-stranded RNA genome. CSFV, along with Bovine Viral Diarrhea Virus (BVDV) and Border Disease Virus (BDV), are classified as members of the Pestivirus genus within the family Flaviviridae [2]. The CSFV virion contains several structural components, the Core protein and three glycoproteins Erns , E1 and E2, which are structurally associated with the virus envelope. The functional significance of the glycoproteins, in the processes of virus replication and virulence have been studied in some detail [4,5,6,7,8,9,10,11]

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