Structural Insight into CVB3-VLP Non-Adjuvanted Vaccine.

Minna M Hankaniemi,Li Xing,Varpu Marjomäki,Olli H Laitinen,Tingwei Ou,Heikki Hyöty,Saana Soppela,Vesa P Hytönen,Virginia M Stone,Brandon Anson,Outi Väätäinen,Mo A Baikoghli,Malin Flodström-Tullberg,Amirbabak Sioofy-Khojine,Niila V V Saarinen,R Holland Cheng

doi:10.3390/microorganisms8091287

Abstract

Coxsackievirus B (CVB) enteroviruses are common pathogens that can cause acute and chronic myocarditis, dilated cardiomyopathy, aseptic meningitis, and they are hypothesized to be a causal factor in type 1 diabetes. The licensed enterovirus vaccines and those currently in clinical development are traditional inactivated or live attenuated vaccines. Even though these vaccines work well in the prevention of enterovirus diseases, new vaccine technologies, like virus-like particles (VLPs), can offer important advantages in the manufacturing and epitope engineering. We have previously produced VLPs for CVB3 and CVB1 in insect cells. Here, we describe the production of CVB3-VLPs with enhanced production yield and purity using an improved purification method consisting of tangential flow filtration and ion exchange chromatography, which is compatible with industrial scale production. We also resolved the CVB3-VLP structure by Cryo-Electron Microscopy imaging and single particle reconstruction. The VLP diameter is 30.9 nm on average, and it is similar to Coxsackievirus A VLPs and the expanded enterovirus cell-entry intermediate (the 135s particle), which is ~2 nm larger than the mature virion. High neutralizing and total IgG antibody levels, the latter being a predominantly Th2 type (IgG1) phenotype, were detected in C57BL/6J mice immunized with non-adjuvanted CVB3-VLP vaccine. The structural and immunogenic data presented here indicate the potential of this improved methodology to produce highly immunogenic enterovirus VLP-vaccines in the future.

Highlights

Coxsackievirus B3 (CVB3) is an RNA virus that belongs to the enterovirus genus of Picornaviridae
CVB3-virus-like particles (VLPs) have been earlier produced using the Bac-to-Bac baculovirus-insect cell expression system, where the P1 polyprotein was expressed under polh promoter and 3CD protease was expressed under p10 promoter [13]
The 3CD protease was produced in low levels, which decreases the toxic effects of 3CD on the host cells and allows the baculovirus-infected insect cells to produce higher amounts of VLP compared to the previous design

Summary

Introduction

Coxsackievirus B3 (CVB3) is an RNA virus that belongs to the enterovirus genus of Picornaviridae. Infections caused by the six Coxsackievirus B serotypes (CVB1-6) usually manifest in mild flu-like symptoms or respiratory illness. CVBs can infect several organs after primary infection, such as the nervous system, pancreas, and heart [1]. Such disseminated infections can lead to severe organ damage and serious diseases including aseptic meningitis, encephalitis, pancreatitis, and myocarditis. CVB3 is the enterovirus most often responsible for viral myocarditis [2] and it can cause hand, foot, and mouth disease (HFMD) outbreaks [3]. CVBs have been considered as potent targets for the future enterovirus vaccines [6,7,8]

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