The assembly of virus-like particles of porcine transmissible gastroenteritis virus in vitro by baculovirus expression system

Abstract

Virus-like particles (VLPs) produced by recombinant expression of the major viral structural proteins could be an attractive method for transmissible gastroenteritis virus (TGEV) assembly and release. In this study, the M gene, sM gene, and N gene of TGEV were inserted into donor plasmid pFastBac Dual. Those recombinant donor plasmids were transformed into E.coli DH10Bac respectively. Recombinant baculoviruses were obtained by transfection of the Sf9 cells with Bacmid-M, Bacmid-sM, and Bacmid-N. The results of indirect immunofluorescence assay showed that recombinant M protein, sM protein, and N protein were expressed successfully. In vitro experiments of VLP assembly of TGEV were performed by infection of insect cells with various combinations of recombinant baculoviruses identified. It is shown that expression of M protein alone, coexpression of M plus sM protein, and coexpression of M plus N protein in Sf9 insect cells infected by recombinant baculovirus could result in the occurrence of a virion morphologically similar to TGEV. However, the sM and N protein could not generate a structure similar to the virion of TGEV when expressed alone. This study provides a theoretical foundation for further study on the role of TGEV structural proteins in the assembly process of virions.