Construction Of Bm-bacmid And Prokaryotic Expression Of Porcine Circovirus Typ Ii's Capsid

Baculoviruses are obligate lethal pathogens of arthropodas and their main hosts are insects. They have been highly valued and widely studied since being exploited as expression vectors. Their particular advantages and excellent performances have been fully demonstrated in areas such as biology, agriculture, medicine and zymetology, which exhibited great potential applied values. Baculoviruses, whereas, have disadvantages. As a result, we reconstructed BmNPV and hoped to refine it as a better expression vector.With the help of red recombinase system, we substitued the sequence between chitinase and cathepsin with a vector termed CopyControl? pCC1BAC?. Then we get a BmNPV shuttle plasmid designated as Bm-Bacmid. They have one replication orgin from Escherichia coli and a high-effecient replication factor. The replication orgin maintain single copy and the high-effecient replication factor can initiate amplification of plasmid number when induced by L-arabinose. Deleting chitinase and cathepsin can enhance their expression performance too. ORF1629 is an essential gene for baculovirus replication. We destroyed ORF1629 and polyhedrin gene simultaneously. This defective virus can effectively replicate in E. coli while have to recombin with transfer vectors and thus repired to be reproductive virus in insect cells, which can effectively decrease the background of wild baculoviruses. The egt(ecdysteroid UDP glucosyltransferase)is a gene that encode glucosyltransferase. It is reported that egt can influence the physiological status of insects. And we predict this may helpful for expressing foreign protein so we have knocked out egt form BmNPV.Porcine circovirus type 2(PCV2)is the main pathogen of Postweaning multisystemic wasting syndrome (PMWS). It is spherical, non-enveloped, icosahedral symmetrical vius with a single-stranded closed circular genomic DNA of 1,767 or 1,768 bp. Despite its small genome, PCV2 can cause great loss to the pig-raising industry. As a result, develop an effective vaccine is an important and urgent task. Former research revealed that the capsid of PCV2 show strong immunogenicity and can elicite protective antibody against PCV2. Here we expressed the capsid of PCV2 in E. coli and thus facilitate examination the expression result in other expression systerms including that of baculovirus.