Expression Of N Gene From Porcine Transmissible Gastroenteritis Virus TH-98 Strain In E.coli And Purification Of Recombinant Nucleoprotein

Porcine transmissible gastroenteristis is an importan contagious disease endangering thedevelopment of swine. In other to establish a rapid diagnosis method and provide effectiveimmunogenic products, the nucleoprotein (N) gene of porcine transmissible gastroenteristisvirus (TGEV) was cloned. expressed and its expressed product was purified. Semm samplesfrom immuned rabbits of PHN recombinan protein were examined for anti-TGEVneutralizing activity.The results were showed as follows:The viral subgenome mRNA of porcine transmissible gastroenteristis virus (TGEV) wasamplified by RT-PCR using primer pairs Li01 and Li02 which designed according to thereported reference. A DNA fragment which is about 1200bp was amplified and then the DNAfragement was cloned specially into pProEXHTb vector between the NspV and Xhol cleavagesite. The recombinant plasmid PHN was transformed into E.coli DH5 α. Then it was analyzedby sequencing and homology cornparing. The result shows that TGEV N gene consists of amature protein of 382 amino acids. TGEV N gene of strain TH-98 is the sazne in length andshares 99%. 97%. 97%. 95%. 96% identities with strain Purdue-115. strain FS772/70. strainTO14. strain 96-l933 and Strain TFI in nucleotide respectively and shares 99%. 97%. 98% .96%. 97% identities in amino acids respectively.The E.coli Strain DH5 α transformed recombinant plasmid PHN was induced with 0.6mmol/m IPTG for N gene expression. The expressed product was identified by SDS-PAGE andWestem-blot test, a fusion protein about 47ku as we expected was found. The results showsthat the vitro expressed protein of N gene by recombinant plasmid vector in the E.colimaintains anigenicity of TGEVThe recombinant protein was purified acconiing to the vector self characteristic (Hisk APolyhishdine tag introduced at the amino-acid terminus of the nucleoprotein allowed for thepurification of protein by nickel-chelate dsity chromataography We explored allpossibilities of pedcation and gained the modified purification method. Several conditions,which include diffend pH Buffer and concelltheion of imidazole, were selected to purifyrecombinan nucleorotein. The result showed that IPTG-induced cell pellets was extmetedin 10 ml of buffer A conwt lmmol/L PMSF, Ni 2+-NTA colunin was serially washed with20ml of buffe A and 20ml of buffer B, then recombinant proteins were eluted from the2COlam Wlm 8u rmoDL lIIllarle ln buner L. rmetlon was collectCQ anQ me absorbanceswas monitOred at 280 nm wave, the high adrity-purified recombinan protein preparation wasobtained.The rabbitS were haIntmed with purified recombinant protein and the sera wereexamined fOr anti-TGEV neutralwi astivity on the continuous POrcine IBRS2 cells.Theresult shOwed that neutraldrig activity was 1:22. Therefore,the neuthelizing activity of anti Nprotein antibody against infectious TGEV in vitro was very Iow from the result ofneutra1hation (VN) test.Tang Ljie Major f Prevenhve Veterinary ScienceTutOr: Professor Li Yiing...