Expression of porcine deltacoronavirus S protein in insect cells and preparation and identification of monoclonal antibody
Porcine deltacoronavirus(PDCoV),a newly discovered virus in recent years,can cause severe diarrhea,vomiting,dehydration and even death in piglets.S protein is an important structur-al protein of PDCoV,which determines the host or tissue tropism of the virus,and is an important target for the development of PDCoV vaccines and detection methods.In order to prepare mono-clonal antibody(MAb)against the S protein of PDCoV,the recombinant plasmid of S protein was constructed based on the extracellular domain sequence of S protein of PDCoV epidemic strain in China and transformed into DH10Bac competent cells.The recombinant bacmid was identified by blue-white spot screening and PCR.BALB/c mice were immunized with S protein,and the spleen cells of immunized mice were fused with myeloma cells.The positive hybridoma cells that secreted stable antibodies were screened by indirect ELISA and subcloning.Five hybridoma cell superna-tants(MAb)specifically recognizing S protein(2E5,4D5,5D10,2F7 and 5A9)were identified by Western blot and immunofluorescence assay(IFA).Subsequently,the neutralization test showed that three of the monoclonal antibodies(2E5,4D5 and 5D10)could neutralize the virus to varying degrees.The S protein was successfully expressed and 5 monoclonal antibodies that can stably se-crete and specifically bind to PDCoV and S protein were prepared,which laid an important founda-tion for further research on the structure and function of S protein,the development of detection methods for PDCoV infection,and the prevention or treatment of PDCoV infection.