Development of a Foot-and-Mouth Disease Virus Serotype A Empty Capsid Subunit Vaccine Using Silkworm (Bombyx mori) Pupae

Zhiyong Li,Yinü Li,Yun Zhang,Jixing Liu,Hang Liu,Xuerui Li,Yongzhu Yi,Xiangping Yin,Zhifang Zhang,Ming Liu

doi:10.1371/journal.pone.0043849

Abstract

Foot-and-mouth disease (FMD) is a highly contagious disease of cloven-hoofed animals that inflicts severe economic losses in the livestock industry. In 2009, FMDV serotype A caused outbreaks of FMD in cattle in China. Although an inactivated virus vaccine has proven effective to control FMD, its use may lead to new disease outbreaks due to a possible incomplete inactivation of the virus during the manufacturing process. Here, we expressed the P1-2A and the 3C coding regions of a serotype A FMDV field isolate in silkworm pupae (Bombyx mori) and evaluated the immunogenicity of the expression products. Four of five cattle vaccinated with these proteins developed high titers of FMDV-specific antibody and were completely protected against virulent homologous virus challenge with 10,000 50% bovine infectious doses (BID50). Furthermore, the 50% bovine protective dose (PD50) test was performed to assess the bovine potency of the empty capsid subunit vaccine and was shown to achieve 4.33 PD50 per dose. These data provide evidence that silkworm pupae can be used to express immunogenic FMDV proteins. This strategy might be used to develop a new generation of empty capsid subunit vaccines against a variety of diseases.

Highlights

Foot-and-mouth disease (FMD) is a highly contagious disease of livestock that causes severe economic loss in susceptible clovenhoofed animals, such as cattle, swine, sheep, and goats
Expression of Polyprotein in Silkworm Pupae Similar to the FMD virus (FMDV) antigen used as positive control, antigencapture sandwich-enzyme-linked immunosorbent assay (ELISA) indicated that the signal detected in the pupae infected with rBmNPV (P1-2A3C) decreased with dilution (Fig. 2)
The expressed empty capsid-like particles in silkworm pupae were purified by gel filtration through a Sepharose 4 Fast Flow (FF) column

Summary

Introduction

Foot-and-mouth disease (FMD) is a highly contagious disease of livestock that causes severe economic loss in susceptible clovenhoofed animals, such as cattle, swine, sheep, and goats. Since inactivated vaccines contain various amounts of contaminating viral non-structural proteins, it may be difficult to distinguish vaccinated from infected animals [4]. To overcome these issues, a number of different types of vaccines have been developed including synthesized peptide vaccines [5,6], recombinant virus-vectored vaccines [4,7,8,9,10,11], empty capsid subunit vaccines [12,13,14], DNA vaccines [15,16], and an oral vaccine produced in transgenic plants [17]. Compared to the silkworm larvae, the silkworm pupae are more convenient for large-scale production and can be used to express the protein at any time without the limitation of supplying mulberry leaves

Methods

Results

Conclusion