Expression of the M and N Protein Gene of Porcine Reproductive and Respiratory Syndrome Virus in E ．coli

The primers for RT PCR were designed on the basis of M and N gene sequence of PRRSV. A gene fragment about 900 bp, which has digestion sites of EcoRI and BamHI, was amplified by RT PCR. The M and N gene were cloned into expression vector pBV220 and one recombinant PBVMN was constructed which highly expressed a 34 kD protein in \%E. coli\% DH 5 . The expressed product was identified by SDS PAGE and Western blotting, which occupies 12% of total bacterial protein. The report has laid a basis for the development of molecular diagnostic antigen of PRRSV.