Cloning and expression of duck C3d cDNA.

C3d is the final split product of complement C3.In order to develop it's immune enhancement,the study extracted the total cell RNA from the liver of duck and the cDNA of C3d was amplified by reverse transcription polymerase chain reaction(RT-PCR).The positive plasmid which contained C3d cDNA was determinded by cloning and sequencing.After the fragments were cloned into PGEX-6P-1,the recombinant plasmid was then transformed into E.coli BL21,and was induced with IPTG for gene expression.The expressed product was identified by SDS-PAGE and Western-blotting.It is approved that the recombinant protein is the C3d.The study provides foundation for development and utilization of duck C3d.