In vitro expression of the goose astrovirus Cap protein delivered with a duck enteritis virus vector.

Abstract

Background: Goose astrovirus (GAstV) is an emerging pathogen that is widely distributed throughout China and can cause visceral gout, resulting in serious economic losses for the goose industry. Open reading frame 2 (ORF2) of this virus encodes the precursor capsid protein, which is essential for the assembly and antigenicity of these virions. To construct a bi-valent vaccine for controlling GAstV and duck enteritis virus (DEV) infection, an infectious bacterial artificial chromosome (BAC) clone of the DEV vaccine strain pDEV-EF1 was used to establish a recombinant DEV vector for GAstV ORF2 gene delivery.

Methods: GAstV ORF2 expression frame was inserted into the US7 and US8 intergenic region of DEV genome by Red E/T two-step recombinant technology, then the recombinant virus rDEV-GAstV ORF2 was rescued by transfecting recombinant clone pDEV-GAstV ORF2 into chicken embryonic fibroblasts (CEFs). The expression of ORF2 in CEFs and formation of virus-like particles (VLPs) were analysed by Western blotting, indirect immunofluorescence assay (IFA) and immunogold electron microscopy (IEM), individually. And protein celluar localization was analysed by IFA.

Results: Using this rDEV-GAstV ORF2 vector to infect CEFs was sufficient to elicit GAstV Cap protein expression, as confirmed by Western blotting and IFA. IEM also revealed the formation of VLPs within cells expressing this Cap protein.

Conclusions: DEV is a good viral vector for GAstV ORF2 gene delivery and these results provide a basis for the development of a bivalent vaccine for controlling DEV and GAstV infections.